diff mbox series

[v2,8/9] KVM: selftests: Add a CoCo-specific test for KVM_PRE_FAULT_MEMORY

Message ID 20240816192310.117456-9-pratikrajesh.sampat@amd.com
State Superseded
Headers show
Series SEV Kernel Selftests | expand

Commit Message

Pratik R. Sampat Aug. 16, 2024, 7:23 p.m. UTC
From: Michael Roth <michael.roth@amd.com>

SEV, SEV-ES, and SNP have a few corner cases where there is potential
for KVM_PRE_FAULT_MEMORY to behave differently depending on when it is
issued during initial guest setup. Exercising these various paths
requires a bit more fine-grained control over when the
KVM_PRE_FAULT_MEMORY requests are issued while setting up the guests.

Since these CoCo-specific events are likely to be architecture-specific
KST helpers, take the existing generic test in pre_fault_memory_test.c
as a starting template, and then introduce an x86-specific version of
it with expanded coverage for SEV, SEV-ES, and SNP.

Since there's a reasonable chance that TDX could extend this for similar
testing of TDX, give it a "coco-" prefix rather than an SEV-specific
one.

Signed-off-by: Michael Roth <michael.roth@amd.com>
Co-developed-by: Pratik R. Sampat <pratikrajesh.sampat@amd.com>
Signed-off-by: Pratik R. Sampat <pratikrajesh.sampat@amd.com>
---
 tools/testing/selftests/kvm/Makefile          |   1 +
 .../kvm/x86_64/coco_pre_fault_memory_test.c   | 314 ++++++++++++++++++
 2 files changed, 315 insertions(+)
 create mode 100644 tools/testing/selftests/kvm/x86_64/coco_pre_fault_memory_test.c

Comments

Aithal, Srikanth Aug. 20, 2024, 6:24 a.m. UTC | #1
On 8/17/2024 12:53 AM, Pratik R. Sampat wrote:
> From: Michael Roth <michael.roth@amd.com>
> 
> SEV, SEV-ES, and SNP have a few corner cases where there is potential
> for KVM_PRE_FAULT_MEMORY to behave differently depending on when it is
> issued during initial guest setup. Exercising these various paths
> requires a bit more fine-grained control over when the
> KVM_PRE_FAULT_MEMORY requests are issued while setting up the guests.
> 
> Since these CoCo-specific events are likely to be architecture-specific
> KST helpers, take the existing generic test in pre_fault_memory_test.c
> as a starting template, and then introduce an x86-specific version of
> it with expanded coverage for SEV, SEV-ES, and SNP.
> 
> Since there's a reasonable chance that TDX could extend this for similar
> testing of TDX, give it a "coco-" prefix rather than an SEV-specific
> one.
> 
> Signed-off-by: Michael Roth <michael.roth@amd.com>
> Co-developed-by: Pratik R. Sampat <pratikrajesh.sampat@amd.com>
> Signed-off-by: Pratik R. Sampat <pratikrajesh.sampat@amd.com>
> ---
>   tools/testing/selftests/kvm/Makefile          |   1 +
>   .../kvm/x86_64/coco_pre_fault_memory_test.c   | 314 ++++++++++++++++++
>   2 files changed, 315 insertions(+)
>   create mode 100644 tools/testing/selftests/kvm/x86_64/coco_pre_fault_memory_test.c
> 
> diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
> index 48d32c5aa3eb..65d19b277b06 100644
> --- a/tools/testing/selftests/kvm/Makefile
> +++ b/tools/testing/selftests/kvm/Makefile
> @@ -129,6 +129,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/amx_test
>   TEST_GEN_PROGS_x86_64 += x86_64/max_vcpuid_cap_test
>   TEST_GEN_PROGS_x86_64 += x86_64/triple_fault_event_test
>   TEST_GEN_PROGS_x86_64 += x86_64/recalc_apic_map_test
> +TEST_GEN_PROGS_x86_64 += x86_64/coco_pre_fault_memory_test
>   TEST_GEN_PROGS_x86_64 += access_tracking_perf_test
>   TEST_GEN_PROGS_x86_64 += demand_paging_test
>   TEST_GEN_PROGS_x86_64 += dirty_log_test
> diff --git a/tools/testing/selftests/kvm/x86_64/coco_pre_fault_memory_test.c b/tools/testing/selftests/kvm/x86_64/coco_pre_fault_memory_test.c
> new file mode 100644
> index 000000000000..e16fe185fb5a
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/x86_64/coco_pre_fault_memory_test.c
> @@ -0,0 +1,314 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#include <linux/sizes.h>
> +
> +#include <test_util.h>
> +#include <kvm_util.h>
> +#include <processor.h>
> +#include "sev.h"
> +
> +/* Arbitrarily chosen values */
> +#define TEST_SIZE		(SZ_2M + PAGE_SIZE)
> +#define TEST_NPAGES		(TEST_SIZE / PAGE_SIZE)
> +#define TEST_SLOT		10
> +#define TEST_GPA		0x100000000ul
> +#define TEST_GVA		0x100000000ul
> +
> +enum prefault_snp_test_type {
> +	/* Skip pre-faulting tests. */
> +	NO_PREFAULT_TYPE = 0,
> +	/*
> +	 * Issue KVM_PRE_FAULT_MEMORY for GFNs mapping non-private memory
> +	 * before finalizing the initial guest contents (e.g. via
> +	 * KVM_SEV_SNP_LAUNCH_FINISH for SNP guests).
> +	 *
> +	 * This should result in failure since KVM explicitly disallows
> +	 * KVM_PRE_FAULT_MEMORY from being issued prior to finalizing the
> +	 * initial guest contents.
> +	 */
> +	PREFAULT_SHARED_BEFORE_FINALIZING = 0,
> +	/*
> +	 * Issue KVM_PRE_FAULT_MEMORY for GFNs mapping private memory
> +	 * before finalizing the initial guest contents (e.g. via
> +	 * KVM_SEV_SNP_LAUNCH_FINISH for SNP guests).
> +	 *
> +	 * This should result in failure since KVM explicitly disallows
> +	 * KVM_PRE_FAULT_MEMORY from being issued prior to finalizing the
> +	 * initial guest contents.
> +	 */
> +	PREFAULT_PRIVATE_BEFORE_FINALIZING,
> +	/*
> +	 * Issue KVM_PRE_FAULT_MEMORY for GFNs mapping shared/private
> +	 * memory after finalizing the initial guest contents
> +	 * (e.g. via * KVM_SEV_SNP_LAUNCH_FINISH for SNP guests).
> +	 *
> +	 * This should succeed since pre-faulting is supported for both
> +	 * non-private/private memory once the guest contents are finalized.
> +	 */
> +	PREFAULT_PRIVATE_SHARED_AFTER_FINALIZING
> +};
> +
> +static void guest_code_sev(void)
> +{
> +	int i;
> +
> +	GUEST_ASSERT(rdmsr(MSR_AMD64_SEV) & MSR_AMD64_SEV_ENABLED);
> +
> +	for (i = 0; i < TEST_NPAGES; i++) {
> +		uint64_t *src = (uint64_t *)(TEST_GVA + i * PAGE_SIZE);
> +		uint64_t val = *src;
> +
> +		/* Validate the data stored in the pages */
> +		if ((i < TEST_NPAGES / 2 && val != i + 1) ||
> +		    (i >= TEST_NPAGES / 2 && val != 0)) {
> +			GUEST_FAIL("Inconsistent view of memory values in guest");
> +		}
> +	}
> +
> +	if (rdmsr(MSR_AMD64_SEV) & MSR_AMD64_SEV_ES_ENABLED) {
> +		wrmsr(MSR_AMD64_SEV_ES_GHCB, GHCB_MSR_TERM_REQ);
> +		__asm__ __volatile__("rep; vmmcall");
> +		GUEST_FAIL("This should be unreachable.");
> +	}
> +
> +	GUEST_DONE();
> +}
> +
> +static void __pre_fault_memory(struct kvm_vcpu *vcpu, u64 gpa, u64 size,
> +			       u64 left, bool expect_fail)
> +{
> +	struct kvm_pre_fault_memory range = {
> +		.gpa = gpa,
> +		.size = size,
> +		.flags = 0,
> +	};
> +	int ret, save_errno;
> +	u64 prev;
> +
> +	do {
> +		prev = range.size;
> +		ret = __vcpu_ioctl(vcpu, KVM_PRE_FAULT_MEMORY, &range);
> +		save_errno = errno;
> +		TEST_ASSERT((range.size < prev) ^ (ret < 0),
> +			    "%sexpecting range.size to change on %s",
> +			    ret < 0 ? "not " : "",
> +			    ret < 0 ? "failure" : "success");
> +	} while (ret >= 0 ? range.size : save_errno == EINTR);
> +
> +	TEST_ASSERT(expect_fail ? !(range.size == left) : (range.size == left),
> +		    "[EXPECT %s] completed with %lld bytes left, expected %" PRId64,
> +		    expect_fail ? "FAIL" : "PASS",
> +		    range.size, left);
> +
> +	if (left == 0) {
> +		TEST_ASSERT(expect_fail ? ret : !ret,
> +			    "[EXPECT %s] KVM_PRE_FAULT_MEMORY",
> +			    expect_fail ? "FAIL" : "PASS");
> +	} else {
> +		/*
> +		 * For shared memory, no memory slot causes RET_PF_EMULATE. It
> +		 * results in -ENOENT.
> +		 *
> +		 * For private memory, no memory slot is an error case returning
> +		 * -EFAULT, but it also possible the only the GPA ranges backed
> +		 *  by a slot are marked as private, in which case the noslot
> +		 *  range will also result in -ENOENT.
> +		 *
> +		 *  So allow both errors for now, but in the future it would be
> +		 *  good to distinguish between these cases to tighten up the
> +		 *  error-checking.
> +		 */
> +		TEST_ASSERT(expect_fail ? !ret :
> +			    (ret && (save_errno == EFAULT || save_errno == ENOENT)),
> +			    "[EXPECT %s] KVM_PRE_FAULT_MEMORY",
> +			    expect_fail ? "FAIL" : "PASS");
> +	}
> +}
> +
> +static void pre_fault_memory(struct kvm_vcpu *vcpu, u64 gpa,
> +			     u64 size, u64 left)
> +{
> +	__pre_fault_memory(vcpu, gpa, size, left, false);
> +}
> +
> +static void pre_fault_memory_negative(struct kvm_vcpu *vcpu, u64 gpa,
> +				      u64 size, u64 left)
> +{
> +	__pre_fault_memory(vcpu, gpa, size, left, true);
> +}
> +
> +static void pre_fault_memory_snp(struct kvm_vcpu *vcpu, struct kvm_vm *vm,
> +				 bool private, enum prefault_snp_test_type p_type)
> +{
> +	if (p_type == PREFAULT_SHARED_BEFORE_FINALIZING)
> +		pre_fault_memory_negative(vcpu, TEST_GPA, SZ_2M, 0);
> +
> +	snp_vm_launch_start(vm, SNP_POLICY);
> +
> +	if (p_type == PREFAULT_SHARED_BEFORE_FINALIZING)
> +		pre_fault_memory_negative(vcpu, TEST_GPA, SZ_2M, 0);
> +
> +	if (private) {
> +		/*
> +		 * Make sure when pages are pre-faulted later after
> +		 * finalization they are treated the same as a private
> +		 * access by the guest so that the expected gmem
> +		 * backing pages are used.
> +		 */
> +		vm_mem_set_private(vm, TEST_GPA, TEST_SIZE);
> +		if (p_type == PREFAULT_PRIVATE_BEFORE_FINALIZING)
> +			pre_fault_memory_negative(vcpu, TEST_GPA, SZ_2M, 0);
> +	} else {
> +		if (p_type == PREFAULT_SHARED_BEFORE_FINALIZING)
> +			pre_fault_memory_negative(vcpu, TEST_GPA, SZ_2M, 0);
> +	}
> +
> +	snp_vm_launch_update(vm);
> +
> +	if (p_type == PREFAULT_SHARED_BEFORE_FINALIZING)
> +		pre_fault_memory_negative(vcpu, TEST_GPA, SZ_2M, 0);
> +
> +	snp_vm_launch_finish(vm);
> +
> +	/*
> +	 * After finalization, pre-faulting either private or shared
> +	 * ranges should work regardless of whether the pages were
> +	 * encrypted as part of setting up initial guest state.
> +	 */
> +	if (p_type == PREFAULT_PRIVATE_SHARED_AFTER_FINALIZING) {
> +		pre_fault_memory(vcpu, TEST_GPA, SZ_2M, 0);
> +		pre_fault_memory(vcpu, TEST_GPA + SZ_2M, PAGE_SIZE * 2, PAGE_SIZE);
> +		pre_fault_memory(vcpu, TEST_GPA + TEST_SIZE, PAGE_SIZE, PAGE_SIZE);
> +	}
> +}
> +
> +static void pre_fault_memory_sev(unsigned long vm_type, struct kvm_vcpu *vcpu,
> +				 struct kvm_vm *vm)
> +{
> +	uint32_t policy = (vm_type == KVM_X86_SEV_ES_VM) ? SEV_POLICY_ES : 0;
> +
> +	pre_fault_memory(vcpu, TEST_GPA, SZ_2M, 0);
> +	pre_fault_memory(vcpu, TEST_GPA + SZ_2M, PAGE_SIZE * 2, PAGE_SIZE);
> +	pre_fault_memory(vcpu, TEST_GPA + TEST_SIZE, PAGE_SIZE, PAGE_SIZE);
> +
> +	sev_vm_launch(vm, policy);
> +
> +	pre_fault_memory(vcpu, TEST_GPA, SZ_2M, 0);
> +	pre_fault_memory(vcpu, TEST_GPA + SZ_2M, PAGE_SIZE * 2, PAGE_SIZE);
> +	pre_fault_memory(vcpu, TEST_GPA + TEST_SIZE, PAGE_SIZE, PAGE_SIZE);
> +
> +	sev_vm_launch_measure(vm, alloca(256));
> +
> +	pre_fault_memory(vcpu, TEST_GPA, SZ_2M, 0);
> +	pre_fault_memory(vcpu, TEST_GPA + SZ_2M, PAGE_SIZE * 2, PAGE_SIZE);
> +	pre_fault_memory(vcpu, TEST_GPA + TEST_SIZE, PAGE_SIZE, PAGE_SIZE);
> +
> +	sev_vm_launch_finish(vm);
> +
> +	pre_fault_memory(vcpu, TEST_GPA, SZ_2M, 0);
> +	pre_fault_memory(vcpu, TEST_GPA + SZ_2M, PAGE_SIZE * 2, PAGE_SIZE);
> +	pre_fault_memory(vcpu, TEST_GPA + TEST_SIZE, PAGE_SIZE, PAGE_SIZE);
> +}
> +
> +static void test_pre_fault_memory_sev(unsigned long vm_type, bool private,
> +				      enum prefault_snp_test_type p_type)
> +{
> +	struct kvm_vcpu *vcpu;
> +	struct kvm_vm *vm;
> +	struct ucall uc;
> +	int i;
> +
> +	vm = vm_sev_create_with_one_vcpu(vm_type, guest_code_sev, &vcpu);
> +
> +	vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS,
> +				    TEST_GPA, TEST_SLOT, TEST_NPAGES,
> +				    (vm_type == KVM_X86_SNP_VM) ? KVM_MEM_GUEST_MEMFD : 0);
> +
> +	/*
> +	 * Make sure guest page table is in agreement with what pages will be
> +	 * initially encrypted by the ASP.
> +	 */
> +	if (private)
> +		vm_mem_set_protected(vm, TEST_SLOT, TEST_GPA, TEST_NPAGES);
> +
> +	virt_map(vm, TEST_GVA, TEST_GPA, TEST_NPAGES);
> +
> +	/*
> +	 * Populate the pages to compare data read from the guest
> +	 * Populate the first half with data and second half as all zeros.
> +	 */
> +	for (i = 0; i < TEST_NPAGES; i++) {
> +		uint64_t *hva = addr_gva2hva(vm, TEST_GVA + i * PAGE_SIZE);
> +
> +		if (i < TEST_NPAGES / 2)
> +			*hva = i + 1;
> +		else
> +			*hva = 0;
> +	}
> +
> +	if (vm_type == KVM_X86_SNP_VM)
> +		pre_fault_memory_snp(vcpu, vm, private, p_type);
> +	else
> +		pre_fault_memory_sev(vm_type, vcpu, vm);
> +
> +	vcpu_run(vcpu);
> +
> +	if (vm->type == KVM_X86_SEV_ES_VM || vm->type == KVM_X86_SNP_VM) {
> +		TEST_ASSERT(vcpu->run->exit_reason == KVM_EXIT_SYSTEM_EVENT,
> +			    "Wanted SYSTEM_EVENT, got %s",
> +			    exit_reason_str(vcpu->run->exit_reason));
> +		TEST_ASSERT_EQ(vcpu->run->system_event.type, KVM_SYSTEM_EVENT_SEV_TERM);
> +		TEST_ASSERT_EQ(vcpu->run->system_event.ndata, 1);
> +		TEST_ASSERT_EQ(vcpu->run->system_event.data[0], GHCB_MSR_TERM_REQ);
> +		goto out;
> +	}
> +
> +	switch (get_ucall(vcpu, &uc)) {
> +	case UCALL_DONE:
> +		break;
> +	case UCALL_ABORT:
> +		REPORT_GUEST_ASSERT(uc);
> +	default:
> +		TEST_FAIL("Unexpected exit: %s",
> +			  exit_reason_str(vcpu->run->exit_reason));
> +	}
> +
> +out:
> +	kvm_vm_free(vm);
> +}
> +
> +static void test_pre_fault_memory(unsigned long vm_type, bool private)
> +{
> +	int pt;
> +
> +	if (vm_type && !(kvm_check_cap(KVM_CAP_VM_TYPES) & BIT(vm_type))) {
> +		pr_info("Skipping tests for vm_type 0x%lx\n", vm_type);
> +		return;
> +	}
> +
> +	switch (vm_type) {
> +	case KVM_X86_SEV_VM:
> +	case KVM_X86_SEV_ES_VM:
> +		test_pre_fault_memory_sev(vm_type, private, NO_PREFAULT_TYPE);
> +		break;
> +	case KVM_X86_SNP_VM:
> +		for (pt = 0; pt <= PREFAULT_PRIVATE_SHARED_AFTER_FINALIZING; pt++)
> +			test_pre_fault_memory_sev(vm_type, private, pt);
> +		break;
> +	default:
> +		abort();
> +	}
> +}
> +
> +int main(int argc, char *argv[])
> +{
> +	TEST_REQUIRE(kvm_check_cap(KVM_CAP_PRE_FAULT_MEMORY));
> +
> +	test_pre_fault_memory(KVM_X86_SEV_VM, false);
> +	test_pre_fault_memory(KVM_X86_SEV_VM, true);
> +	test_pre_fault_memory(KVM_X86_SEV_ES_VM, false);
> +	test_pre_fault_memory(KVM_X86_SEV_ES_VM, true);
> +	test_pre_fault_memory(KVM_X86_SNP_VM, false);
> +	test_pre_fault_memory(KVM_X86_SNP_VM, true);
> +
> +	return 0;
> +}

Hello Pratik,
I see below failure while running this test [kvm-x86/next + mentioned 
patches]:

# selftests: kvm: coco_pre_fault_memory_test
# Random seed: 0x6b8b4567
# ==== Test Assertion Failure ====
#   x86_64/coco_pre_fault_memory_test.c:145: expect_fail ? !(range.size 
== left) : (range.size == left)
#   pid=202665 tid=202665 errno=9 - Bad file descriptor
#      1        0x0000000000402870: __pre_fault_memory at 
coco_pre_fault_memory_test.c:145
#      2        0x00000000004031c9: pre_fault_memory_negative at 
coco_pre_fault_memory_test.c:184
#      3         (inlined by) pre_fault_memory_snp at 
coco_pre_fault_memory_test.c:202
#      4         (inlined by) test_pre_fault_memory_sev at 
coco_pre_fault_memory_test.c:344
#      5        0x00000000004033c0: test_pre_fault_memory at 
coco_pre_fault_memory_test.c:401 (discriminator 3)
#      6        0x00000000004024d7: main at 
coco_pre_fault_memory_test.c:417 (discriminator 2)
#      7        0x00007f9474829d8f: ?? ??:0
#      8        0x00007f9474829e3f: ?? ??:0
#      9        0x0000000000402574: _start at ??:?
#   [EXPECT FAIL] completed with 0 bytes left, expected 0
not ok 66 selftests: kvm: coco_pre_fault_memory_test # exit=254
Pratik R. Sampat Aug. 22, 2024, 4:32 p.m. UTC | #2
On 8/20/2024 1:24 AM, Aithal, Srikanth wrote:
> On 8/17/2024 12:53 AM, Pratik R. Sampat wrote:
>> From: Michael Roth <michael.roth@amd.com>
>>
>> SEV, SEV-ES, and SNP have a few corner cases where there is potential
>> for KVM_PRE_FAULT_MEMORY to behave differently depending on when it is
>> issued during initial guest setup. Exercising these various paths
>> requires a bit more fine-grained control over when the
>> KVM_PRE_FAULT_MEMORY requests are issued while setting up the guests.
>>
>> Since these CoCo-specific events are likely to be architecture-specific
>> KST helpers, take the existing generic test in pre_fault_memory_test.c
>> as a starting template, and then introduce an x86-specific version of
>> it with expanded coverage for SEV, SEV-ES, and SNP.
>>
>> Since there's a reasonable chance that TDX could extend this for similar
>> testing of TDX, give it a "coco-" prefix rather than an SEV-specific
>> one.
>>
>> Signed-off-by: Michael Roth <michael.roth@amd.com>
>> Co-developed-by: Pratik R. Sampat <pratikrajesh.sampat@amd.com>
>> Signed-off-by: Pratik R. Sampat <pratikrajesh.sampat@amd.com>
>> ---
>>   tools/testing/selftests/kvm/Makefile          |   1 +
>>   .../kvm/x86_64/coco_pre_fault_memory_test.c   | 314 ++++++++++++++++++
>>   2 files changed, 315 insertions(+)
>>   create mode 100644 tools/testing/selftests/kvm/x86_64/
>> coco_pre_fault_memory_test.c
>>
>> diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/
>> selftests/kvm/Makefile
>> index 48d32c5aa3eb..65d19b277b06 100644
>> --- a/tools/testing/selftests/kvm/Makefile
>> +++ b/tools/testing/selftests/kvm/Makefile
>> @@ -129,6 +129,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/amx_test
>>   TEST_GEN_PROGS_x86_64 += x86_64/max_vcpuid_cap_test
>>   TEST_GEN_PROGS_x86_64 += x86_64/triple_fault_event_test
>>   TEST_GEN_PROGS_x86_64 += x86_64/recalc_apic_map_test
>> +TEST_GEN_PROGS_x86_64 += x86_64/coco_pre_fault_memory_test
>>   TEST_GEN_PROGS_x86_64 += access_tracking_perf_test
>>   TEST_GEN_PROGS_x86_64 += demand_paging_test
>>   TEST_GEN_PROGS_x86_64 += dirty_log_test
>> diff --git a/tools/testing/selftests/kvm/x86_64/
>> coco_pre_fault_memory_test.c b/tools/testing/selftests/kvm/x86_64/
>> coco_pre_fault_memory_test.c
>> new file mode 100644
>> index 000000000000..e16fe185fb5a
>> --- /dev/null
>> +++ b/tools/testing/selftests/kvm/x86_64/coco_pre_fault_memory_test.c
>> @@ -0,0 +1,314 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +#include <linux/sizes.h>
>> +
>> +#include <test_util.h>
>> +#include <kvm_util.h>
>> +#include <processor.h>
>> +#include "sev.h"
>> +
>> +/* Arbitrarily chosen values */
>> +#define TEST_SIZE        (SZ_2M + PAGE_SIZE)
>> +#define TEST_NPAGES        (TEST_SIZE / PAGE_SIZE)
>> +#define TEST_SLOT        10
>> +#define TEST_GPA        0x100000000ul
>> +#define TEST_GVA        0x100000000ul
>> +
>> +enum prefault_snp_test_type {
>> +    /* Skip pre-faulting tests. */
>> +    NO_PREFAULT_TYPE = 0,
>> +    /*
>> +     * Issue KVM_PRE_FAULT_MEMORY for GFNs mapping non-private memory
>> +     * before finalizing the initial guest contents (e.g. via
>> +     * KVM_SEV_SNP_LAUNCH_FINISH for SNP guests).
>> +     *
>> +     * This should result in failure since KVM explicitly disallows
>> +     * KVM_PRE_FAULT_MEMORY from being issued prior to finalizing the
>> +     * initial guest contents.
>> +     */
>> +    PREFAULT_SHARED_BEFORE_FINALIZING = 0,
>> +    /*
>> +     * Issue KVM_PRE_FAULT_MEMORY for GFNs mapping private memory
>> +     * before finalizing the initial guest contents (e.g. via
>> +     * KVM_SEV_SNP_LAUNCH_FINISH for SNP guests).
>> +     *
>> +     * This should result in failure since KVM explicitly disallows
>> +     * KVM_PRE_FAULT_MEMORY from being issued prior to finalizing the
>> +     * initial guest contents.
>> +     */
>> +    PREFAULT_PRIVATE_BEFORE_FINALIZING,
>> +    /*
>> +     * Issue KVM_PRE_FAULT_MEMORY for GFNs mapping shared/private
>> +     * memory after finalizing the initial guest contents
>> +     * (e.g. via * KVM_SEV_SNP_LAUNCH_FINISH for SNP guests).
>> +     *
>> +     * This should succeed since pre-faulting is supported for both
>> +     * non-private/private memory once the guest contents are finalized.
>> +     */
>> +    PREFAULT_PRIVATE_SHARED_AFTER_FINALIZING
>> +};
>> +
>> +static void guest_code_sev(void)
>> +{
>> +    int i;
>> +
>> +    GUEST_ASSERT(rdmsr(MSR_AMD64_SEV) & MSR_AMD64_SEV_ENABLED);
>> +
>> +    for (i = 0; i < TEST_NPAGES; i++) {
>> +        uint64_t *src = (uint64_t *)(TEST_GVA + i * PAGE_SIZE);
>> +        uint64_t val = *src;
>> +
>> +        /* Validate the data stored in the pages */
>> +        if ((i < TEST_NPAGES / 2 && val != i + 1) ||
>> +            (i >= TEST_NPAGES / 2 && val != 0)) {
>> +            GUEST_FAIL("Inconsistent view of memory values in guest");
>> +        }
>> +    }
>> +
>> +    if (rdmsr(MSR_AMD64_SEV) & MSR_AMD64_SEV_ES_ENABLED) {
>> +        wrmsr(MSR_AMD64_SEV_ES_GHCB, GHCB_MSR_TERM_REQ);
>> +        __asm__ __volatile__("rep; vmmcall");
>> +        GUEST_FAIL("This should be unreachable.");
>> +    }
>> +
>> +    GUEST_DONE();
>> +}
>> +
>> +static void __pre_fault_memory(struct kvm_vcpu *vcpu, u64 gpa, u64 size,
>> +                   u64 left, bool expect_fail)
>> +{
>> +    struct kvm_pre_fault_memory range = {
>> +        .gpa = gpa,
>> +        .size = size,
>> +        .flags = 0,
>> +    };
>> +    int ret, save_errno;
>> +    u64 prev;
>> +
>> +    do {
>> +        prev = range.size;
>> +        ret = __vcpu_ioctl(vcpu, KVM_PRE_FAULT_MEMORY, &range);
>> +        save_errno = errno;
>> +        TEST_ASSERT((range.size < prev) ^ (ret < 0),
>> +                "%sexpecting range.size to change on %s",
>> +                ret < 0 ? "not " : "",
>> +                ret < 0 ? "failure" : "success");
>> +    } while (ret >= 0 ? range.size : save_errno == EINTR);
>> +
>> +    TEST_ASSERT(expect_fail ? !(range.size == left) : (range.size ==
>> left),
>> +            "[EXPECT %s] completed with %lld bytes left, expected %"
>> PRId64,
>> +            expect_fail ? "FAIL" : "PASS",
>> +            range.size, left);
>> +
>> +    if (left == 0) {
>> +        TEST_ASSERT(expect_fail ? ret : !ret,
>> +                "[EXPECT %s] KVM_PRE_FAULT_MEMORY",
>> +                expect_fail ? "FAIL" : "PASS");
>> +    } else {
>> +        /*
>> +         * For shared memory, no memory slot causes RET_PF_EMULATE. It
>> +         * results in -ENOENT.
>> +         *
>> +         * For private memory, no memory slot is an error case returning
>> +         * -EFAULT, but it also possible the only the GPA ranges backed
>> +         *  by a slot are marked as private, in which case the noslot
>> +         *  range will also result in -ENOENT.
>> +         *
>> +         *  So allow both errors for now, but in the future it would be
>> +         *  good to distinguish between these cases to tighten up the
>> +         *  error-checking.
>> +         */
>> +        TEST_ASSERT(expect_fail ? !ret :
>> +                (ret && (save_errno == EFAULT || save_errno == ENOENT)),
>> +                "[EXPECT %s] KVM_PRE_FAULT_MEMORY",
>> +                expect_fail ? "FAIL" : "PASS");
>> +    }
>> +}
>> +
>> +static void pre_fault_memory(struct kvm_vcpu *vcpu, u64 gpa,
>> +                 u64 size, u64 left)
>> +{
>> +    __pre_fault_memory(vcpu, gpa, size, left, false);
>> +}
>> +
>> +static void pre_fault_memory_negative(struct kvm_vcpu *vcpu, u64 gpa,
>> +                      u64 size, u64 left)
>> +{
>> +    __pre_fault_memory(vcpu, gpa, size, left, true);
>> +}
>> +
>> +static void pre_fault_memory_snp(struct kvm_vcpu *vcpu, struct kvm_vm
>> *vm,
>> +                 bool private, enum prefault_snp_test_type p_type)
>> +{
>> +    if (p_type == PREFAULT_SHARED_BEFORE_FINALIZING)
>> +        pre_fault_memory_negative(vcpu, TEST_GPA, SZ_2M, 0);
>> +
>> +    snp_vm_launch_start(vm, SNP_POLICY);
>> +
>> +    if (p_type == PREFAULT_SHARED_BEFORE_FINALIZING)
>> +        pre_fault_memory_negative(vcpu, TEST_GPA, SZ_2M, 0);
>> +
>> +    if (private) {
>> +        /*
>> +         * Make sure when pages are pre-faulted later after
>> +         * finalization they are treated the same as a private
>> +         * access by the guest so that the expected gmem
>> +         * backing pages are used.
>> +         */
>> +        vm_mem_set_private(vm, TEST_GPA, TEST_SIZE);
>> +        if (p_type == PREFAULT_PRIVATE_BEFORE_FINALIZING)
>> +            pre_fault_memory_negative(vcpu, TEST_GPA, SZ_2M, 0);
>> +    } else {
>> +        if (p_type == PREFAULT_SHARED_BEFORE_FINALIZING)
>> +            pre_fault_memory_negative(vcpu, TEST_GPA, SZ_2M, 0);
>> +    }
>> +
>> +    snp_vm_launch_update(vm);
>> +
>> +    if (p_type == PREFAULT_SHARED_BEFORE_FINALIZING)
>> +        pre_fault_memory_negative(vcpu, TEST_GPA, SZ_2M, 0);
>> +
>> +    snp_vm_launch_finish(vm);
>> +
>> +    /*
>> +     * After finalization, pre-faulting either private or shared
>> +     * ranges should work regardless of whether the pages were
>> +     * encrypted as part of setting up initial guest state.
>> +     */
>> +    if (p_type == PREFAULT_PRIVATE_SHARED_AFTER_FINALIZING) {
>> +        pre_fault_memory(vcpu, TEST_GPA, SZ_2M, 0);
>> +        pre_fault_memory(vcpu, TEST_GPA + SZ_2M, PAGE_SIZE * 2,
>> PAGE_SIZE);
>> +        pre_fault_memory(vcpu, TEST_GPA + TEST_SIZE, PAGE_SIZE,
>> PAGE_SIZE);
>> +    }
>> +}
>> +
>> +static void pre_fault_memory_sev(unsigned long vm_type, struct
>> kvm_vcpu *vcpu,
>> +                 struct kvm_vm *vm)
>> +{
>> +    uint32_t policy = (vm_type == KVM_X86_SEV_ES_VM) ?
>> SEV_POLICY_ES : 0;
>> +
>> +    pre_fault_memory(vcpu, TEST_GPA, SZ_2M, 0);
>> +    pre_fault_memory(vcpu, TEST_GPA + SZ_2M, PAGE_SIZE * 2, PAGE_SIZE);
>> +    pre_fault_memory(vcpu, TEST_GPA + TEST_SIZE, PAGE_SIZE, PAGE_SIZE);
>> +
>> +    sev_vm_launch(vm, policy);
>> +
>> +    pre_fault_memory(vcpu, TEST_GPA, SZ_2M, 0);
>> +    pre_fault_memory(vcpu, TEST_GPA + SZ_2M, PAGE_SIZE * 2, PAGE_SIZE);
>> +    pre_fault_memory(vcpu, TEST_GPA + TEST_SIZE, PAGE_SIZE, PAGE_SIZE);
>> +
>> +    sev_vm_launch_measure(vm, alloca(256));
>> +
>> +    pre_fault_memory(vcpu, TEST_GPA, SZ_2M, 0);
>> +    pre_fault_memory(vcpu, TEST_GPA + SZ_2M, PAGE_SIZE * 2, PAGE_SIZE);
>> +    pre_fault_memory(vcpu, TEST_GPA + TEST_SIZE, PAGE_SIZE, PAGE_SIZE);
>> +
>> +    sev_vm_launch_finish(vm);
>> +
>> +    pre_fault_memory(vcpu, TEST_GPA, SZ_2M, 0);
>> +    pre_fault_memory(vcpu, TEST_GPA + SZ_2M, PAGE_SIZE * 2, PAGE_SIZE);
>> +    pre_fault_memory(vcpu, TEST_GPA + TEST_SIZE, PAGE_SIZE, PAGE_SIZE);
>> +}
>> +
>> +static void test_pre_fault_memory_sev(unsigned long vm_type, bool
>> private,
>> +                      enum prefault_snp_test_type p_type)
>> +{
>> +    struct kvm_vcpu *vcpu;
>> +    struct kvm_vm *vm;
>> +    struct ucall uc;
>> +    int i;
>> +
>> +    vm = vm_sev_create_with_one_vcpu(vm_type, guest_code_sev, &vcpu);
>> +
>> +    vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS,
>> +                    TEST_GPA, TEST_SLOT, TEST_NPAGES,
>> +                    (vm_type == KVM_X86_SNP_VM) ?
>> KVM_MEM_GUEST_MEMFD : 0);
>> +
>> +    /*
>> +     * Make sure guest page table is in agreement with what pages
>> will be
>> +     * initially encrypted by the ASP.
>> +     */
>> +    if (private)
>> +        vm_mem_set_protected(vm, TEST_SLOT, TEST_GPA, TEST_NPAGES);
>> +
>> +    virt_map(vm, TEST_GVA, TEST_GPA, TEST_NPAGES);
>> +
>> +    /*
>> +     * Populate the pages to compare data read from the guest
>> +     * Populate the first half with data and second half as all zeros.
>> +     */
>> +    for (i = 0; i < TEST_NPAGES; i++) {
>> +        uint64_t *hva = addr_gva2hva(vm, TEST_GVA + i * PAGE_SIZE);
>> +
>> +        if (i < TEST_NPAGES / 2)
>> +            *hva = i + 1;
>> +        else
>> +            *hva = 0;
>> +    }
>> +
>> +    if (vm_type == KVM_X86_SNP_VM)
>> +        pre_fault_memory_snp(vcpu, vm, private, p_type);
>> +    else
>> +        pre_fault_memory_sev(vm_type, vcpu, vm);
>> +
>> +    vcpu_run(vcpu);
>> +
>> +    if (vm->type == KVM_X86_SEV_ES_VM || vm->type == KVM_X86_SNP_VM) {
>> +        TEST_ASSERT(vcpu->run->exit_reason == KVM_EXIT_SYSTEM_EVENT,
>> +                "Wanted SYSTEM_EVENT, got %s",
>> +                exit_reason_str(vcpu->run->exit_reason));
>> +        TEST_ASSERT_EQ(vcpu->run->system_event.type,
>> KVM_SYSTEM_EVENT_SEV_TERM);
>> +        TEST_ASSERT_EQ(vcpu->run->system_event.ndata, 1);
>> +        TEST_ASSERT_EQ(vcpu->run->system_event.data[0],
>> GHCB_MSR_TERM_REQ);
>> +        goto out;
>> +    }
>> +
>> +    switch (get_ucall(vcpu, &uc)) {
>> +    case UCALL_DONE:
>> +        break;
>> +    case UCALL_ABORT:
>> +        REPORT_GUEST_ASSERT(uc);
>> +    default:
>> +        TEST_FAIL("Unexpected exit: %s",
>> +              exit_reason_str(vcpu->run->exit_reason));
>> +    }
>> +
>> +out:
>> +    kvm_vm_free(vm);
>> +}
>> +
>> +static void test_pre_fault_memory(unsigned long vm_type, bool private)
>> +{
>> +    int pt;
>> +
>> +    if (vm_type && !(kvm_check_cap(KVM_CAP_VM_TYPES) & BIT(vm_type))) {
>> +        pr_info("Skipping tests for vm_type 0x%lx\n", vm_type);
>> +        return;
>> +    }
>> +
>> +    switch (vm_type) {
>> +    case KVM_X86_SEV_VM:
>> +    case KVM_X86_SEV_ES_VM:
>> +        test_pre_fault_memory_sev(vm_type, private, NO_PREFAULT_TYPE);
>> +        break;
>> +    case KVM_X86_SNP_VM:
>> +        for (pt = 0; pt <= PREFAULT_PRIVATE_SHARED_AFTER_FINALIZING;
>> pt++)
>> +            test_pre_fault_memory_sev(vm_type, private, pt);
>> +        break;
>> +    default:
>> +        abort();
>> +    }
>> +}
>> +
>> +int main(int argc, char *argv[])
>> +{
>> +    TEST_REQUIRE(kvm_check_cap(KVM_CAP_PRE_FAULT_MEMORY));
>> +
>> +    test_pre_fault_memory(KVM_X86_SEV_VM, false);
>> +    test_pre_fault_memory(KVM_X86_SEV_VM, true);
>> +    test_pre_fault_memory(KVM_X86_SEV_ES_VM, false);
>> +    test_pre_fault_memory(KVM_X86_SEV_ES_VM, true);
>> +    test_pre_fault_memory(KVM_X86_SNP_VM, false);
>> +    test_pre_fault_memory(KVM_X86_SNP_VM, true);
>> +
>> +    return 0;
>> +}
> 
> Hello Pratik,
> I see below failure while running this test [kvm-x86/next + mentioned
> patches]:
> 
> # selftests: kvm: coco_pre_fault_memory_test
> # Random seed: 0x6b8b4567
> # ==== Test Assertion Failure ====
> #   x86_64/coco_pre_fault_memory_test.c:145: expect_fail ? !(range.size
> == left) : (range.size == left)
> #   pid=202665 tid=202665 errno=9 - Bad file descriptor
> #      1        0x0000000000402870: __pre_fault_memory at
> coco_pre_fault_memory_test.c:145
> #      2        0x00000000004031c9: pre_fault_memory_negative at
> coco_pre_fault_memory_test.c:184
> #      3         (inlined by) pre_fault_memory_snp at
> coco_pre_fault_memory_test.c:202
> #      4         (inlined by) test_pre_fault_memory_sev at
> coco_pre_fault_memory_test.c:344
> #      5        0x00000000004033c0: test_pre_fault_memory at
> coco_pre_fault_memory_test.c:401 (discriminator 3)
> #      6        0x00000000004024d7: main at
> coco_pre_fault_memory_test.c:417 (discriminator 2)
> #      7        0x00007f9474829d8f: ?? ??:0
> #      8        0x00007f9474829e3f: ?? ??:0
> #      9        0x0000000000402574: _start at ??:?
> #   [EXPECT FAIL] completed with 0 bytes left, expected 0
> not ok 66 selftests: kvm: coco_pre_fault_memory_test # exit=254
> 

Hi Srikanth,

Thanks for testing these patches.

I believe that you may have to test these patches either over the
kvm-x86/fixes branch or over kvm/[queue/next] since there are a few
fixes (eg. KVM: x86: disallow pre-fault for SNP VMs before
initialization, etc.) which are not present in kvm-x86/next.

Do let me know if that works for you instead for the tests?

Thanks!
Pratik
> 
>
Pratik R. Sampat Aug. 23, 2024, 8:23 p.m. UTC | #3
On 8/16/2024 2:23 PM, Pratik R. Sampat wrote:
> From: Michael Roth <michael.roth@amd.com>
> 
> SEV, SEV-ES, and SNP have a few corner cases where there is potential
> for KVM_PRE_FAULT_MEMORY to behave differently depending on when it is
> issued during initial guest setup. Exercising these various paths
> requires a bit more fine-grained control over when the
> KVM_PRE_FAULT_MEMORY requests are issued while setting up the guests.
> 
> Since these CoCo-specific events are likely to be architecture-specific
> KST helpers, take the existing generic test in pre_fault_memory_test.c
> as a starting template, and then introduce an x86-specific version of
> it with expanded coverage for SEV, SEV-ES, and SNP.
> 
> Since there's a reasonable chance that TDX could extend this for similar
> testing of TDX, give it a "coco-" prefix rather than an SEV-specific
> one.
> 
> Signed-off-by: Michael Roth <michael.roth@amd.com>
> Co-developed-by: Pratik R. Sampat <pratikrajesh.sampat@amd.com>
> Signed-off-by: Pratik R. Sampat <pratikrajesh.sampat@amd.com>
> ---
>  tools/testing/selftests/kvm/Makefile          |   1 +
>  .../kvm/x86_64/coco_pre_fault_memory_test.c   | 314 ++++++++++++++++++
>  2 files changed, 315 insertions(+)
>  create mode 100644 tools/testing/selftests/kvm/x86_64/coco_pre_fault_memory_test.c
> 
> diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
> index 48d32c5aa3eb..65d19b277b06 100644
> --- a/tools/testing/selftests/kvm/Makefile
> +++ b/tools/testing/selftests/kvm/Makefile
> @@ -129,6 +129,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/amx_test
>  TEST_GEN_PROGS_x86_64 += x86_64/max_vcpuid_cap_test
>  TEST_GEN_PROGS_x86_64 += x86_64/triple_fault_event_test
>  TEST_GEN_PROGS_x86_64 += x86_64/recalc_apic_map_test
> +TEST_GEN_PROGS_x86_64 += x86_64/coco_pre_fault_memory_test
>  TEST_GEN_PROGS_x86_64 += access_tracking_perf_test
>  TEST_GEN_PROGS_x86_64 += demand_paging_test
>  TEST_GEN_PROGS_x86_64 += dirty_log_test
> diff --git a/tools/testing/selftests/kvm/x86_64/coco_pre_fault_memory_test.c b/tools/testing/selftests/kvm/x86_64/coco_pre_fault_memory_test.c
> new file mode 100644
> index 000000000000..e16fe185fb5a
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/x86_64/coco_pre_fault_memory_test.c
> @@ -0,0 +1,314 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#include <linux/sizes.h>
> +
> +#include <test_util.h>
> +#include <kvm_util.h>
> +#include <processor.h>
> +#include "sev.h"
> +
> +/* Arbitrarily chosen values */
> +#define TEST_SIZE		(SZ_2M + PAGE_SIZE)
> +#define TEST_NPAGES		(TEST_SIZE / PAGE_SIZE)
> +#define TEST_SLOT		10
> +#define TEST_GPA		0x100000000ul
> +#define TEST_GVA		0x100000000ul
> +
> +enum prefault_snp_test_type {
> +	/* Skip pre-faulting tests. */
> +	NO_PREFAULT_TYPE = 0,
> +	/*
> +	 * Issue KVM_PRE_FAULT_MEMORY for GFNs mapping non-private memory
> +	 * before finalizing the initial guest contents (e.g. via
> +	 * KVM_SEV_SNP_LAUNCH_FINISH for SNP guests).
> +	 *
> +	 * This should result in failure since KVM explicitly disallows
> +	 * KVM_PRE_FAULT_MEMORY from being issued prior to finalizing the
> +	 * initial guest contents.
> +	 */
> +	PREFAULT_SHARED_BEFORE_FINALIZING = 0,

Just spotted that I have initialized both NO_PREFAULT_TYPE and
PREFAULT_SHARED_BEFORE_FINALIZING to 0, effectively running the latter
test type twice. I will fix in the next iteration that I post.

Thanks!
Pratik

> +	/*
> +	 * Issue KVM_PRE_FAULT_MEMORY for GFNs mapping private memory
> +	 * before finalizing the initial guest contents (e.g. via
> +	 * KVM_SEV_SNP_LAUNCH_FINISH for SNP guests).
> +	 *
> +	 * This should result in failure since KVM explicitly disallows
> +	 * KVM_PRE_FAULT_MEMORY from being issued prior to finalizing the
> +	 * initial guest contents.
> +	 */
> +	PREFAULT_PRIVATE_BEFORE_FINALIZING,
> +	/*
> +	 * Issue KVM_PRE_FAULT_MEMORY for GFNs mapping shared/private
> +	 * memory after finalizing the initial guest contents
> +	 * (e.g. via * KVM_SEV_SNP_LAUNCH_FINISH for SNP guests).
> +	 *
> +	 * This should succeed since pre-faulting is supported for both
> +	 * non-private/private memory once the guest contents are finalized.
> +	 */
> +	PREFAULT_PRIVATE_SHARED_AFTER_FINALIZING
> +};
> +
> +static void guest_code_sev(void)
> +{
> +	int i;
> +
> +	GUEST_ASSERT(rdmsr(MSR_AMD64_SEV) & MSR_AMD64_SEV_ENABLED);
> +
> +	for (i = 0; i < TEST_NPAGES; i++) {
> +		uint64_t *src = (uint64_t *)(TEST_GVA + i * PAGE_SIZE);
> +		uint64_t val = *src;
> +
> +		/* Validate the data stored in the pages */
> +		if ((i < TEST_NPAGES / 2 && val != i + 1) ||
> +		    (i >= TEST_NPAGES / 2 && val != 0)) {
> +			GUEST_FAIL("Inconsistent view of memory values in guest");
> +		}
> +	}
> +
> +	if (rdmsr(MSR_AMD64_SEV) & MSR_AMD64_SEV_ES_ENABLED) {
> +		wrmsr(MSR_AMD64_SEV_ES_GHCB, GHCB_MSR_TERM_REQ);
> +		__asm__ __volatile__("rep; vmmcall");
> +		GUEST_FAIL("This should be unreachable.");
> +	}
> +
> +	GUEST_DONE();
> +}
> +
> +static void __pre_fault_memory(struct kvm_vcpu *vcpu, u64 gpa, u64 size,
> +			       u64 left, bool expect_fail)
> +{
> +	struct kvm_pre_fault_memory range = {
> +		.gpa = gpa,
> +		.size = size,
> +		.flags = 0,
> +	};
> +	int ret, save_errno;
> +	u64 prev;
> +
> +	do {
> +		prev = range.size;
> +		ret = __vcpu_ioctl(vcpu, KVM_PRE_FAULT_MEMORY, &range);
> +		save_errno = errno;
> +		TEST_ASSERT((range.size < prev) ^ (ret < 0),
> +			    "%sexpecting range.size to change on %s",
> +			    ret < 0 ? "not " : "",
> +			    ret < 0 ? "failure" : "success");
> +	} while (ret >= 0 ? range.size : save_errno == EINTR);
> +
> +	TEST_ASSERT(expect_fail ? !(range.size == left) : (range.size == left),
> +		    "[EXPECT %s] completed with %lld bytes left, expected %" PRId64,
> +		    expect_fail ? "FAIL" : "PASS",
> +		    range.size, left);
> +
> +	if (left == 0) {
> +		TEST_ASSERT(expect_fail ? ret : !ret,
> +			    "[EXPECT %s] KVM_PRE_FAULT_MEMORY",
> +			    expect_fail ? "FAIL" : "PASS");
> +	} else {
> +		/*
> +		 * For shared memory, no memory slot causes RET_PF_EMULATE. It
> +		 * results in -ENOENT.
> +		 *
> +		 * For private memory, no memory slot is an error case returning
> +		 * -EFAULT, but it also possible the only the GPA ranges backed
> +		 *  by a slot are marked as private, in which case the noslot
> +		 *  range will also result in -ENOENT.
> +		 *
> +		 *  So allow both errors for now, but in the future it would be
> +		 *  good to distinguish between these cases to tighten up the
> +		 *  error-checking.
> +		 */
> +		TEST_ASSERT(expect_fail ? !ret :
> +			    (ret && (save_errno == EFAULT || save_errno == ENOENT)),
> +			    "[EXPECT %s] KVM_PRE_FAULT_MEMORY",
> +			    expect_fail ? "FAIL" : "PASS");
> +	}
> +}
> +
> +static void pre_fault_memory(struct kvm_vcpu *vcpu, u64 gpa,
> +			     u64 size, u64 left)
> +{
> +	__pre_fault_memory(vcpu, gpa, size, left, false);
> +}
> +
> +static void pre_fault_memory_negative(struct kvm_vcpu *vcpu, u64 gpa,
> +				      u64 size, u64 left)
> +{
> +	__pre_fault_memory(vcpu, gpa, size, left, true);
> +}
> +
> +static void pre_fault_memory_snp(struct kvm_vcpu *vcpu, struct kvm_vm *vm,
> +				 bool private, enum prefault_snp_test_type p_type)
> +{
> +	if (p_type == PREFAULT_SHARED_BEFORE_FINALIZING)
> +		pre_fault_memory_negative(vcpu, TEST_GPA, SZ_2M, 0);
> +
> +	snp_vm_launch_start(vm, SNP_POLICY);
> +
> +	if (p_type == PREFAULT_SHARED_BEFORE_FINALIZING)
> +		pre_fault_memory_negative(vcpu, TEST_GPA, SZ_2M, 0);
> +
> +	if (private) {
> +		/*
> +		 * Make sure when pages are pre-faulted later after
> +		 * finalization they are treated the same as a private
> +		 * access by the guest so that the expected gmem
> +		 * backing pages are used.
> +		 */
> +		vm_mem_set_private(vm, TEST_GPA, TEST_SIZE);
> +		if (p_type == PREFAULT_PRIVATE_BEFORE_FINALIZING)
> +			pre_fault_memory_negative(vcpu, TEST_GPA, SZ_2M, 0);
> +	} else {
> +		if (p_type == PREFAULT_SHARED_BEFORE_FINALIZING)
> +			pre_fault_memory_negative(vcpu, TEST_GPA, SZ_2M, 0);
> +	}
> +
> +	snp_vm_launch_update(vm);
> +
> +	if (p_type == PREFAULT_SHARED_BEFORE_FINALIZING)
> +		pre_fault_memory_negative(vcpu, TEST_GPA, SZ_2M, 0);
> +
> +	snp_vm_launch_finish(vm);
> +
> +	/*
> +	 * After finalization, pre-faulting either private or shared
> +	 * ranges should work regardless of whether the pages were
> +	 * encrypted as part of setting up initial guest state.
> +	 */
> +	if (p_type == PREFAULT_PRIVATE_SHARED_AFTER_FINALIZING) {
> +		pre_fault_memory(vcpu, TEST_GPA, SZ_2M, 0);
> +		pre_fault_memory(vcpu, TEST_GPA + SZ_2M, PAGE_SIZE * 2, PAGE_SIZE);
> +		pre_fault_memory(vcpu, TEST_GPA + TEST_SIZE, PAGE_SIZE, PAGE_SIZE);
> +	}
> +}
> +
> +static void pre_fault_memory_sev(unsigned long vm_type, struct kvm_vcpu *vcpu,
> +				 struct kvm_vm *vm)
> +{
> +	uint32_t policy = (vm_type == KVM_X86_SEV_ES_VM) ? SEV_POLICY_ES : 0;
> +
> +	pre_fault_memory(vcpu, TEST_GPA, SZ_2M, 0);
> +	pre_fault_memory(vcpu, TEST_GPA + SZ_2M, PAGE_SIZE * 2, PAGE_SIZE);
> +	pre_fault_memory(vcpu, TEST_GPA + TEST_SIZE, PAGE_SIZE, PAGE_SIZE);
> +
> +	sev_vm_launch(vm, policy);
> +
> +	pre_fault_memory(vcpu, TEST_GPA, SZ_2M, 0);
> +	pre_fault_memory(vcpu, TEST_GPA + SZ_2M, PAGE_SIZE * 2, PAGE_SIZE);
> +	pre_fault_memory(vcpu, TEST_GPA + TEST_SIZE, PAGE_SIZE, PAGE_SIZE);
> +
> +	sev_vm_launch_measure(vm, alloca(256));
> +
> +	pre_fault_memory(vcpu, TEST_GPA, SZ_2M, 0);
> +	pre_fault_memory(vcpu, TEST_GPA + SZ_2M, PAGE_SIZE * 2, PAGE_SIZE);
> +	pre_fault_memory(vcpu, TEST_GPA + TEST_SIZE, PAGE_SIZE, PAGE_SIZE);
> +
> +	sev_vm_launch_finish(vm);
> +
> +	pre_fault_memory(vcpu, TEST_GPA, SZ_2M, 0);
> +	pre_fault_memory(vcpu, TEST_GPA + SZ_2M, PAGE_SIZE * 2, PAGE_SIZE);
> +	pre_fault_memory(vcpu, TEST_GPA + TEST_SIZE, PAGE_SIZE, PAGE_SIZE);
> +}
> +
> +static void test_pre_fault_memory_sev(unsigned long vm_type, bool private,
> +				      enum prefault_snp_test_type p_type)
> +{
> +	struct kvm_vcpu *vcpu;
> +	struct kvm_vm *vm;
> +	struct ucall uc;
> +	int i;
> +
> +	vm = vm_sev_create_with_one_vcpu(vm_type, guest_code_sev, &vcpu);
> +
> +	vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS,
> +				    TEST_GPA, TEST_SLOT, TEST_NPAGES,
> +				    (vm_type == KVM_X86_SNP_VM) ? KVM_MEM_GUEST_MEMFD : 0);
> +
> +	/*
> +	 * Make sure guest page table is in agreement with what pages will be
> +	 * initially encrypted by the ASP.
> +	 */
> +	if (private)
> +		vm_mem_set_protected(vm, TEST_SLOT, TEST_GPA, TEST_NPAGES);
> +
> +	virt_map(vm, TEST_GVA, TEST_GPA, TEST_NPAGES);
> +
> +	/*
> +	 * Populate the pages to compare data read from the guest
> +	 * Populate the first half with data and second half as all zeros.
> +	 */
> +	for (i = 0; i < TEST_NPAGES; i++) {
> +		uint64_t *hva = addr_gva2hva(vm, TEST_GVA + i * PAGE_SIZE);
> +
> +		if (i < TEST_NPAGES / 2)
> +			*hva = i + 1;
> +		else
> +			*hva = 0;
> +	}
> +
> +	if (vm_type == KVM_X86_SNP_VM)
> +		pre_fault_memory_snp(vcpu, vm, private, p_type);
> +	else
> +		pre_fault_memory_sev(vm_type, vcpu, vm);
> +
> +	vcpu_run(vcpu);
> +
> +	if (vm->type == KVM_X86_SEV_ES_VM || vm->type == KVM_X86_SNP_VM) {
> +		TEST_ASSERT(vcpu->run->exit_reason == KVM_EXIT_SYSTEM_EVENT,
> +			    "Wanted SYSTEM_EVENT, got %s",
> +			    exit_reason_str(vcpu->run->exit_reason));
> +		TEST_ASSERT_EQ(vcpu->run->system_event.type, KVM_SYSTEM_EVENT_SEV_TERM);
> +		TEST_ASSERT_EQ(vcpu->run->system_event.ndata, 1);
> +		TEST_ASSERT_EQ(vcpu->run->system_event.data[0], GHCB_MSR_TERM_REQ);
> +		goto out;
> +	}
> +
> +	switch (get_ucall(vcpu, &uc)) {
> +	case UCALL_DONE:
> +		break;
> +	case UCALL_ABORT:
> +		REPORT_GUEST_ASSERT(uc);
> +	default:
> +		TEST_FAIL("Unexpected exit: %s",
> +			  exit_reason_str(vcpu->run->exit_reason));
> +	}
> +
> +out:
> +	kvm_vm_free(vm);
> +}
> +
> +static void test_pre_fault_memory(unsigned long vm_type, bool private)
> +{
> +	int pt;
> +
> +	if (vm_type && !(kvm_check_cap(KVM_CAP_VM_TYPES) & BIT(vm_type))) {
> +		pr_info("Skipping tests for vm_type 0x%lx\n", vm_type);
> +		return;
> +	}
> +
> +	switch (vm_type) {
> +	case KVM_X86_SEV_VM:
> +	case KVM_X86_SEV_ES_VM:
> +		test_pre_fault_memory_sev(vm_type, private, NO_PREFAULT_TYPE);
> +		break;
> +	case KVM_X86_SNP_VM:
> +		for (pt = 0; pt <= PREFAULT_PRIVATE_SHARED_AFTER_FINALIZING; pt++)
> +			test_pre_fault_memory_sev(vm_type, private, pt);
> +		break;
> +	default:
> +		abort();
> +	}
> +}
> +
> +int main(int argc, char *argv[])
> +{
> +	TEST_REQUIRE(kvm_check_cap(KVM_CAP_PRE_FAULT_MEMORY));
> +
> +	test_pre_fault_memory(KVM_X86_SEV_VM, false);
> +	test_pre_fault_memory(KVM_X86_SEV_VM, true);
> +	test_pre_fault_memory(KVM_X86_SEV_ES_VM, false);
> +	test_pre_fault_memory(KVM_X86_SEV_ES_VM, true);
> +	test_pre_fault_memory(KVM_X86_SNP_VM, false);
> +	test_pre_fault_memory(KVM_X86_SNP_VM, true);
> +
> +	return 0;
> +}
Tom Lendacky Aug. 23, 2024, 10:16 p.m. UTC | #4
On 8/23/24 15:23, Pratik R. Sampat wrote:
> 
> 
> On 8/16/2024 2:23 PM, Pratik R. Sampat wrote:
>> From: Michael Roth <michael.roth@amd.com>
>>
>> SEV, SEV-ES, and SNP have a few corner cases where there is potential
>> for KVM_PRE_FAULT_MEMORY to behave differently depending on when it is
>> issued during initial guest setup. Exercising these various paths
>> requires a bit more fine-grained control over when the
>> KVM_PRE_FAULT_MEMORY requests are issued while setting up the guests.
>>
>> Since these CoCo-specific events are likely to be architecture-specific
>> KST helpers, take the existing generic test in pre_fault_memory_test.c
>> as a starting template, and then introduce an x86-specific version of
>> it with expanded coverage for SEV, SEV-ES, and SNP.
>>
>> Since there's a reasonable chance that TDX could extend this for similar
>> testing of TDX, give it a "coco-" prefix rather than an SEV-specific
>> one.
>>
>> Signed-off-by: Michael Roth <michael.roth@amd.com>
>> Co-developed-by: Pratik R. Sampat <pratikrajesh.sampat@amd.com>
>> Signed-off-by: Pratik R. Sampat <pratikrajesh.sampat@amd.com>
>> ---
>>  tools/testing/selftests/kvm/Makefile          |   1 +
>>  .../kvm/x86_64/coco_pre_fault_memory_test.c   | 314 ++++++++++++++++++
>>  2 files changed, 315 insertions(+)
>>  create mode 100644 tools/testing/selftests/kvm/x86_64/coco_pre_fault_memory_test.c
>>
>> diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
>> index 48d32c5aa3eb..65d19b277b06 100644
>> --- a/tools/testing/selftests/kvm/Makefile
>> +++ b/tools/testing/selftests/kvm/Makefile
>> @@ -129,6 +129,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/amx_test
>>  TEST_GEN_PROGS_x86_64 += x86_64/max_vcpuid_cap_test
>>  TEST_GEN_PROGS_x86_64 += x86_64/triple_fault_event_test
>>  TEST_GEN_PROGS_x86_64 += x86_64/recalc_apic_map_test
>> +TEST_GEN_PROGS_x86_64 += x86_64/coco_pre_fault_memory_test
>>  TEST_GEN_PROGS_x86_64 += access_tracking_perf_test
>>  TEST_GEN_PROGS_x86_64 += demand_paging_test
>>  TEST_GEN_PROGS_x86_64 += dirty_log_test
>> diff --git a/tools/testing/selftests/kvm/x86_64/coco_pre_fault_memory_test.c b/tools/testing/selftests/kvm/x86_64/coco_pre_fault_memory_test.c
>> new file mode 100644
>> index 000000000000..e16fe185fb5a
>> --- /dev/null
>> +++ b/tools/testing/selftests/kvm/x86_64/coco_pre_fault_memory_test.c
>> @@ -0,0 +1,314 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +#include <linux/sizes.h>
>> +
>> +#include <test_util.h>
>> +#include <kvm_util.h>
>> +#include <processor.h>
>> +#include "sev.h"
>> +
>> +/* Arbitrarily chosen values */
>> +#define TEST_SIZE		(SZ_2M + PAGE_SIZE)
>> +#define TEST_NPAGES		(TEST_SIZE / PAGE_SIZE)
>> +#define TEST_SLOT		10
>> +#define TEST_GPA		0x100000000ul
>> +#define TEST_GVA		0x100000000ul
>> +
>> +enum prefault_snp_test_type {
>> +	/* Skip pre-faulting tests. */
>> +	NO_PREFAULT_TYPE = 0,
>> +	/*
>> +	 * Issue KVM_PRE_FAULT_MEMORY for GFNs mapping non-private memory
>> +	 * before finalizing the initial guest contents (e.g. via
>> +	 * KVM_SEV_SNP_LAUNCH_FINISH for SNP guests).
>> +	 *
>> +	 * This should result in failure since KVM explicitly disallows
>> +	 * KVM_PRE_FAULT_MEMORY from being issued prior to finalizing the
>> +	 * initial guest contents.
>> +	 */
>> +	PREFAULT_SHARED_BEFORE_FINALIZING = 0,
> 
> Just spotted that I have initialized both NO_PREFAULT_TYPE and
> PREFAULT_SHARED_BEFORE_FINALIZING to 0, effectively running the latter
> test type twice. I will fix in the next iteration that I post.

Enums start at 0, so you can just eliminate the assignments.

Thanks,
Tom

> 
> Thanks!
> Pratik
> 
>> +	/*
>> +	 * Issue KVM_PRE_FAULT_MEMORY for GFNs mapping private memory
>> +	 * before finalizing the initial guest contents (e.g. via
>> +	 * KVM_SEV_SNP_LAUNCH_FINISH for SNP guests).
>> +	 *
>> +	 * This should result in failure since KVM explicitly disallows
>> +	 * KVM_PRE_FAULT_MEMORY from being issued prior to finalizing the
>> +	 * initial guest contents.
>> +	 */
>> +	PREFAULT_PRIVATE_BEFORE_FINALIZING,
>> +	/*
>> +	 * Issue KVM_PRE_FAULT_MEMORY for GFNs mapping shared/private
>> +	 * memory after finalizing the initial guest contents
>> +	 * (e.g. via * KVM_SEV_SNP_LAUNCH_FINISH for SNP guests).
>> +	 *
>> +	 * This should succeed since pre-faulting is supported for both
>> +	 * non-private/private memory once the guest contents are finalized.
>> +	 */
>> +	PREFAULT_PRIVATE_SHARED_AFTER_FINALIZING
>> +};
>> +
>> +static void guest_code_sev(void)
>> +{
>> +	int i;
>> +
>> +	GUEST_ASSERT(rdmsr(MSR_AMD64_SEV) & MSR_AMD64_SEV_ENABLED);
>> +
>> +	for (i = 0; i < TEST_NPAGES; i++) {
>> +		uint64_t *src = (uint64_t *)(TEST_GVA + i * PAGE_SIZE);
>> +		uint64_t val = *src;
>> +
>> +		/* Validate the data stored in the pages */
>> +		if ((i < TEST_NPAGES / 2 && val != i + 1) ||
>> +		    (i >= TEST_NPAGES / 2 && val != 0)) {
>> +			GUEST_FAIL("Inconsistent view of memory values in guest");
>> +		}
>> +	}
>> +
>> +	if (rdmsr(MSR_AMD64_SEV) & MSR_AMD64_SEV_ES_ENABLED) {
>> +		wrmsr(MSR_AMD64_SEV_ES_GHCB, GHCB_MSR_TERM_REQ);
>> +		__asm__ __volatile__("rep; vmmcall");
>> +		GUEST_FAIL("This should be unreachable.");
>> +	}
>> +
>> +	GUEST_DONE();
>> +}
>> +
>> +static void __pre_fault_memory(struct kvm_vcpu *vcpu, u64 gpa, u64 size,
>> +			       u64 left, bool expect_fail)
>> +{
>> +	struct kvm_pre_fault_memory range = {
>> +		.gpa = gpa,
>> +		.size = size,
>> +		.flags = 0,
>> +	};
>> +	int ret, save_errno;
>> +	u64 prev;
>> +
>> +	do {
>> +		prev = range.size;
>> +		ret = __vcpu_ioctl(vcpu, KVM_PRE_FAULT_MEMORY, &range);
>> +		save_errno = errno;
>> +		TEST_ASSERT((range.size < prev) ^ (ret < 0),
>> +			    "%sexpecting range.size to change on %s",
>> +			    ret < 0 ? "not " : "",
>> +			    ret < 0 ? "failure" : "success");
>> +	} while (ret >= 0 ? range.size : save_errno == EINTR);
>> +
>> +	TEST_ASSERT(expect_fail ? !(range.size == left) : (range.size == left),
>> +		    "[EXPECT %s] completed with %lld bytes left, expected %" PRId64,
>> +		    expect_fail ? "FAIL" : "PASS",
>> +		    range.size, left);
>> +
>> +	if (left == 0) {
>> +		TEST_ASSERT(expect_fail ? ret : !ret,
>> +			    "[EXPECT %s] KVM_PRE_FAULT_MEMORY",
>> +			    expect_fail ? "FAIL" : "PASS");
>> +	} else {
>> +		/*
>> +		 * For shared memory, no memory slot causes RET_PF_EMULATE. It
>> +		 * results in -ENOENT.
>> +		 *
>> +		 * For private memory, no memory slot is an error case returning
>> +		 * -EFAULT, but it also possible the only the GPA ranges backed
>> +		 *  by a slot are marked as private, in which case the noslot
>> +		 *  range will also result in -ENOENT.
>> +		 *
>> +		 *  So allow both errors for now, but in the future it would be
>> +		 *  good to distinguish between these cases to tighten up the
>> +		 *  error-checking.
>> +		 */
>> +		TEST_ASSERT(expect_fail ? !ret :
>> +			    (ret && (save_errno == EFAULT || save_errno == ENOENT)),
>> +			    "[EXPECT %s] KVM_PRE_FAULT_MEMORY",
>> +			    expect_fail ? "FAIL" : "PASS");
>> +	}
>> +}
>> +
>> +static void pre_fault_memory(struct kvm_vcpu *vcpu, u64 gpa,
>> +			     u64 size, u64 left)
>> +{
>> +	__pre_fault_memory(vcpu, gpa, size, left, false);
>> +}
>> +
>> +static void pre_fault_memory_negative(struct kvm_vcpu *vcpu, u64 gpa,
>> +				      u64 size, u64 left)
>> +{
>> +	__pre_fault_memory(vcpu, gpa, size, left, true);
>> +}
>> +
>> +static void pre_fault_memory_snp(struct kvm_vcpu *vcpu, struct kvm_vm *vm,
>> +				 bool private, enum prefault_snp_test_type p_type)
>> +{
>> +	if (p_type == PREFAULT_SHARED_BEFORE_FINALIZING)
>> +		pre_fault_memory_negative(vcpu, TEST_GPA, SZ_2M, 0);
>> +
>> +	snp_vm_launch_start(vm, SNP_POLICY);
>> +
>> +	if (p_type == PREFAULT_SHARED_BEFORE_FINALIZING)
>> +		pre_fault_memory_negative(vcpu, TEST_GPA, SZ_2M, 0);
>> +
>> +	if (private) {
>> +		/*
>> +		 * Make sure when pages are pre-faulted later after
>> +		 * finalization they are treated the same as a private
>> +		 * access by the guest so that the expected gmem
>> +		 * backing pages are used.
>> +		 */
>> +		vm_mem_set_private(vm, TEST_GPA, TEST_SIZE);
>> +		if (p_type == PREFAULT_PRIVATE_BEFORE_FINALIZING)
>> +			pre_fault_memory_negative(vcpu, TEST_GPA, SZ_2M, 0);
>> +	} else {
>> +		if (p_type == PREFAULT_SHARED_BEFORE_FINALIZING)
>> +			pre_fault_memory_negative(vcpu, TEST_GPA, SZ_2M, 0);
>> +	}
>> +
>> +	snp_vm_launch_update(vm);
>> +
>> +	if (p_type == PREFAULT_SHARED_BEFORE_FINALIZING)
>> +		pre_fault_memory_negative(vcpu, TEST_GPA, SZ_2M, 0);
>> +
>> +	snp_vm_launch_finish(vm);
>> +
>> +	/*
>> +	 * After finalization, pre-faulting either private or shared
>> +	 * ranges should work regardless of whether the pages were
>> +	 * encrypted as part of setting up initial guest state.
>> +	 */
>> +	if (p_type == PREFAULT_PRIVATE_SHARED_AFTER_FINALIZING) {
>> +		pre_fault_memory(vcpu, TEST_GPA, SZ_2M, 0);
>> +		pre_fault_memory(vcpu, TEST_GPA + SZ_2M, PAGE_SIZE * 2, PAGE_SIZE);
>> +		pre_fault_memory(vcpu, TEST_GPA + TEST_SIZE, PAGE_SIZE, PAGE_SIZE);
>> +	}
>> +}
>> +
>> +static void pre_fault_memory_sev(unsigned long vm_type, struct kvm_vcpu *vcpu,
>> +				 struct kvm_vm *vm)
>> +{
>> +	uint32_t policy = (vm_type == KVM_X86_SEV_ES_VM) ? SEV_POLICY_ES : 0;
>> +
>> +	pre_fault_memory(vcpu, TEST_GPA, SZ_2M, 0);
>> +	pre_fault_memory(vcpu, TEST_GPA + SZ_2M, PAGE_SIZE * 2, PAGE_SIZE);
>> +	pre_fault_memory(vcpu, TEST_GPA + TEST_SIZE, PAGE_SIZE, PAGE_SIZE);
>> +
>> +	sev_vm_launch(vm, policy);
>> +
>> +	pre_fault_memory(vcpu, TEST_GPA, SZ_2M, 0);
>> +	pre_fault_memory(vcpu, TEST_GPA + SZ_2M, PAGE_SIZE * 2, PAGE_SIZE);
>> +	pre_fault_memory(vcpu, TEST_GPA + TEST_SIZE, PAGE_SIZE, PAGE_SIZE);
>> +
>> +	sev_vm_launch_measure(vm, alloca(256));
>> +
>> +	pre_fault_memory(vcpu, TEST_GPA, SZ_2M, 0);
>> +	pre_fault_memory(vcpu, TEST_GPA + SZ_2M, PAGE_SIZE * 2, PAGE_SIZE);
>> +	pre_fault_memory(vcpu, TEST_GPA + TEST_SIZE, PAGE_SIZE, PAGE_SIZE);
>> +
>> +	sev_vm_launch_finish(vm);
>> +
>> +	pre_fault_memory(vcpu, TEST_GPA, SZ_2M, 0);
>> +	pre_fault_memory(vcpu, TEST_GPA + SZ_2M, PAGE_SIZE * 2, PAGE_SIZE);
>> +	pre_fault_memory(vcpu, TEST_GPA + TEST_SIZE, PAGE_SIZE, PAGE_SIZE);
>> +}
>> +
>> +static void test_pre_fault_memory_sev(unsigned long vm_type, bool private,
>> +				      enum prefault_snp_test_type p_type)
>> +{
>> +	struct kvm_vcpu *vcpu;
>> +	struct kvm_vm *vm;
>> +	struct ucall uc;
>> +	int i;
>> +
>> +	vm = vm_sev_create_with_one_vcpu(vm_type, guest_code_sev, &vcpu);
>> +
>> +	vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS,
>> +				    TEST_GPA, TEST_SLOT, TEST_NPAGES,
>> +				    (vm_type == KVM_X86_SNP_VM) ? KVM_MEM_GUEST_MEMFD : 0);
>> +
>> +	/*
>> +	 * Make sure guest page table is in agreement with what pages will be
>> +	 * initially encrypted by the ASP.
>> +	 */
>> +	if (private)
>> +		vm_mem_set_protected(vm, TEST_SLOT, TEST_GPA, TEST_NPAGES);
>> +
>> +	virt_map(vm, TEST_GVA, TEST_GPA, TEST_NPAGES);
>> +
>> +	/*
>> +	 * Populate the pages to compare data read from the guest
>> +	 * Populate the first half with data and second half as all zeros.
>> +	 */
>> +	for (i = 0; i < TEST_NPAGES; i++) {
>> +		uint64_t *hva = addr_gva2hva(vm, TEST_GVA + i * PAGE_SIZE);
>> +
>> +		if (i < TEST_NPAGES / 2)
>> +			*hva = i + 1;
>> +		else
>> +			*hva = 0;
>> +	}
>> +
>> +	if (vm_type == KVM_X86_SNP_VM)
>> +		pre_fault_memory_snp(vcpu, vm, private, p_type);
>> +	else
>> +		pre_fault_memory_sev(vm_type, vcpu, vm);
>> +
>> +	vcpu_run(vcpu);
>> +
>> +	if (vm->type == KVM_X86_SEV_ES_VM || vm->type == KVM_X86_SNP_VM) {
>> +		TEST_ASSERT(vcpu->run->exit_reason == KVM_EXIT_SYSTEM_EVENT,
>> +			    "Wanted SYSTEM_EVENT, got %s",
>> +			    exit_reason_str(vcpu->run->exit_reason));
>> +		TEST_ASSERT_EQ(vcpu->run->system_event.type, KVM_SYSTEM_EVENT_SEV_TERM);
>> +		TEST_ASSERT_EQ(vcpu->run->system_event.ndata, 1);
>> +		TEST_ASSERT_EQ(vcpu->run->system_event.data[0], GHCB_MSR_TERM_REQ);
>> +		goto out;
>> +	}
>> +
>> +	switch (get_ucall(vcpu, &uc)) {
>> +	case UCALL_DONE:
>> +		break;
>> +	case UCALL_ABORT:
>> +		REPORT_GUEST_ASSERT(uc);
>> +	default:
>> +		TEST_FAIL("Unexpected exit: %s",
>> +			  exit_reason_str(vcpu->run->exit_reason));
>> +	}
>> +
>> +out:
>> +	kvm_vm_free(vm);
>> +}
>> +
>> +static void test_pre_fault_memory(unsigned long vm_type, bool private)
>> +{
>> +	int pt;
>> +
>> +	if (vm_type && !(kvm_check_cap(KVM_CAP_VM_TYPES) & BIT(vm_type))) {
>> +		pr_info("Skipping tests for vm_type 0x%lx\n", vm_type);
>> +		return;
>> +	}
>> +
>> +	switch (vm_type) {
>> +	case KVM_X86_SEV_VM:
>> +	case KVM_X86_SEV_ES_VM:
>> +		test_pre_fault_memory_sev(vm_type, private, NO_PREFAULT_TYPE);
>> +		break;
>> +	case KVM_X86_SNP_VM:
>> +		for (pt = 0; pt <= PREFAULT_PRIVATE_SHARED_AFTER_FINALIZING; pt++)
>> +			test_pre_fault_memory_sev(vm_type, private, pt);
>> +		break;
>> +	default:
>> +		abort();
>> +	}
>> +}
>> +
>> +int main(int argc, char *argv[])
>> +{
>> +	TEST_REQUIRE(kvm_check_cap(KVM_CAP_PRE_FAULT_MEMORY));
>> +
>> +	test_pre_fault_memory(KVM_X86_SEV_VM, false);
>> +	test_pre_fault_memory(KVM_X86_SEV_VM, true);
>> +	test_pre_fault_memory(KVM_X86_SEV_ES_VM, false);
>> +	test_pre_fault_memory(KVM_X86_SEV_ES_VM, true);
>> +	test_pre_fault_memory(KVM_X86_SNP_VM, false);
>> +	test_pre_fault_memory(KVM_X86_SNP_VM, true);
>> +
>> +	return 0;
>> +}
>
Pratik R. Sampat Aug. 26, 2024, 10 p.m. UTC | #5
On 8/23/2024 5:16 PM, Tom Lendacky wrote:
> On 8/23/24 15:23, Pratik R. Sampat wrote:
>>
>>
>> On 8/16/2024 2:23 PM, Pratik R. Sampat wrote:
>>> From: Michael Roth <michael.roth@amd.com>
>>>
>>> SEV, SEV-ES, and SNP have a few corner cases where there is potential
>>> for KVM_PRE_FAULT_MEMORY to behave differently depending on when it is
>>> issued during initial guest setup. Exercising these various paths
>>> requires a bit more fine-grained control over when the
>>> KVM_PRE_FAULT_MEMORY requests are issued while setting up the guests.
>>>
>>> Since these CoCo-specific events are likely to be architecture-specific
>>> KST helpers, take the existing generic test in pre_fault_memory_test.c
>>> as a starting template, and then introduce an x86-specific version of
>>> it with expanded coverage for SEV, SEV-ES, and SNP.
>>>
>>> Since there's a reasonable chance that TDX could extend this for similar
>>> testing of TDX, give it a "coco-" prefix rather than an SEV-specific
>>> one.
>>>
>>> Signed-off-by: Michael Roth <michael.roth@amd.com>
>>> Co-developed-by: Pratik R. Sampat <pratikrajesh.sampat@amd.com>
>>> Signed-off-by: Pratik R. Sampat <pratikrajesh.sampat@amd.com>
>>> ---
>>>  tools/testing/selftests/kvm/Makefile          |   1 +
>>>  .../kvm/x86_64/coco_pre_fault_memory_test.c   | 314 ++++++++++++++++++
>>>  2 files changed, 315 insertions(+)
>>>  create mode 100644 tools/testing/selftests/kvm/x86_64/coco_pre_fault_memory_test.c
>>>
>>> diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
>>> index 48d32c5aa3eb..65d19b277b06 100644
>>> --- a/tools/testing/selftests/kvm/Makefile
>>> +++ b/tools/testing/selftests/kvm/Makefile
>>> @@ -129,6 +129,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/amx_test
>>>  TEST_GEN_PROGS_x86_64 += x86_64/max_vcpuid_cap_test
>>>  TEST_GEN_PROGS_x86_64 += x86_64/triple_fault_event_test
>>>  TEST_GEN_PROGS_x86_64 += x86_64/recalc_apic_map_test
>>> +TEST_GEN_PROGS_x86_64 += x86_64/coco_pre_fault_memory_test
>>>  TEST_GEN_PROGS_x86_64 += access_tracking_perf_test
>>>  TEST_GEN_PROGS_x86_64 += demand_paging_test
>>>  TEST_GEN_PROGS_x86_64 += dirty_log_test
>>> diff --git a/tools/testing/selftests/kvm/x86_64/coco_pre_fault_memory_test.c b/tools/testing/selftests/kvm/x86_64/coco_pre_fault_memory_test.c
>>> new file mode 100644
>>> index 000000000000..e16fe185fb5a
>>> --- /dev/null
>>> +++ b/tools/testing/selftests/kvm/x86_64/coco_pre_fault_memory_test.c
>>> @@ -0,0 +1,314 @@
>>> +// SPDX-License-Identifier: GPL-2.0
>>> +#include <linux/sizes.h>
>>> +
>>> +#include <test_util.h>
>>> +#include <kvm_util.h>
>>> +#include <processor.h>
>>> +#include "sev.h"
>>> +
>>> +/* Arbitrarily chosen values */
>>> +#define TEST_SIZE		(SZ_2M + PAGE_SIZE)
>>> +#define TEST_NPAGES		(TEST_SIZE / PAGE_SIZE)
>>> +#define TEST_SLOT		10
>>> +#define TEST_GPA		0x100000000ul
>>> +#define TEST_GVA		0x100000000ul
>>> +
>>> +enum prefault_snp_test_type {
>>> +	/* Skip pre-faulting tests. */
>>> +	NO_PREFAULT_TYPE = 0,
>>> +	/*
>>> +	 * Issue KVM_PRE_FAULT_MEMORY for GFNs mapping non-private memory
>>> +	 * before finalizing the initial guest contents (e.g. via
>>> +	 * KVM_SEV_SNP_LAUNCH_FINISH for SNP guests).
>>> +	 *
>>> +	 * This should result in failure since KVM explicitly disallows
>>> +	 * KVM_PRE_FAULT_MEMORY from being issued prior to finalizing the
>>> +	 * initial guest contents.
>>> +	 */
>>> +	PREFAULT_SHARED_BEFORE_FINALIZING = 0,
>>
>> Just spotted that I have initialized both NO_PREFAULT_TYPE and
>> PREFAULT_SHARED_BEFORE_FINALIZING to 0, effectively running the latter
>> test type twice. I will fix in the next iteration that I post.
> 
> Enums start at 0, so you can just eliminate the assignments.
> 

Ack. I Will get rid of it here and the next patch as well.

Thanks!

> Thanks,
> Tom
> 
>>
>> Thanks!
>> Pratik
>>
>>> +	/*
>>> +	 * Issue KVM_PRE_FAULT_MEMORY for GFNs mapping private memory
>>> +	 * before finalizing the initial guest contents (e.g. via
>>> +	 * KVM_SEV_SNP_LAUNCH_FINISH for SNP guests).
>>> +	 *
>>> +	 * This should result in failure since KVM explicitly disallows
>>> +	 * KVM_PRE_FAULT_MEMORY from being issued prior to finalizing the
>>> +	 * initial guest contents.
>>> +	 */
>>> +	PREFAULT_PRIVATE_BEFORE_FINALIZING,
>>> +	/*
>>> +	 * Issue KVM_PRE_FAULT_MEMORY for GFNs mapping shared/private
>>> +	 * memory after finalizing the initial guest contents
>>> +	 * (e.g. via * KVM_SEV_SNP_LAUNCH_FINISH for SNP guests).
>>> +	 *
>>> +	 * This should succeed since pre-faulting is supported for both
>>> +	 * non-private/private memory once the guest contents are finalized.
>>> +	 */
>>> +	PREFAULT_PRIVATE_SHARED_AFTER_FINALIZING
>>> +};
>>> +
>>> +static void guest_code_sev(void)
>>> +{
>>> +	int i;
>>> +
>>> +	GUEST_ASSERT(rdmsr(MSR_AMD64_SEV) & MSR_AMD64_SEV_ENABLED);
>>> +
>>> +	for (i = 0; i < TEST_NPAGES; i++) {
>>> +		uint64_t *src = (uint64_t *)(TEST_GVA + i * PAGE_SIZE);
>>> +		uint64_t val = *src;
>>> +
>>> +		/* Validate the data stored in the pages */
>>> +		if ((i < TEST_NPAGES / 2 && val != i + 1) ||
>>> +		    (i >= TEST_NPAGES / 2 && val != 0)) {
>>> +			GUEST_FAIL("Inconsistent view of memory values in guest");
>>> +		}
>>> +	}
>>> +
>>> +	if (rdmsr(MSR_AMD64_SEV) & MSR_AMD64_SEV_ES_ENABLED) {
>>> +		wrmsr(MSR_AMD64_SEV_ES_GHCB, GHCB_MSR_TERM_REQ);
>>> +		__asm__ __volatile__("rep; vmmcall");
>>> +		GUEST_FAIL("This should be unreachable.");
>>> +	}
>>> +
>>> +	GUEST_DONE();
>>> +}
>>> +
>>> +static void __pre_fault_memory(struct kvm_vcpu *vcpu, u64 gpa, u64 size,
>>> +			       u64 left, bool expect_fail)
>>> +{
>>> +	struct kvm_pre_fault_memory range = {
>>> +		.gpa = gpa,
>>> +		.size = size,
>>> +		.flags = 0,
>>> +	};
>>> +	int ret, save_errno;
>>> +	u64 prev;
>>> +
>>> +	do {
>>> +		prev = range.size;
>>> +		ret = __vcpu_ioctl(vcpu, KVM_PRE_FAULT_MEMORY, &range);
>>> +		save_errno = errno;
>>> +		TEST_ASSERT((range.size < prev) ^ (ret < 0),
>>> +			    "%sexpecting range.size to change on %s",
>>> +			    ret < 0 ? "not " : "",
>>> +			    ret < 0 ? "failure" : "success");
>>> +	} while (ret >= 0 ? range.size : save_errno == EINTR);
>>> +
>>> +	TEST_ASSERT(expect_fail ? !(range.size == left) : (range.size == left),
>>> +		    "[EXPECT %s] completed with %lld bytes left, expected %" PRId64,
>>> +		    expect_fail ? "FAIL" : "PASS",
>>> +		    range.size, left);
>>> +
>>> +	if (left == 0) {
>>> +		TEST_ASSERT(expect_fail ? ret : !ret,
>>> +			    "[EXPECT %s] KVM_PRE_FAULT_MEMORY",
>>> +			    expect_fail ? "FAIL" : "PASS");
>>> +	} else {
>>> +		/*
>>> +		 * For shared memory, no memory slot causes RET_PF_EMULATE. It
>>> +		 * results in -ENOENT.
>>> +		 *
>>> +		 * For private memory, no memory slot is an error case returning
>>> +		 * -EFAULT, but it also possible the only the GPA ranges backed
>>> +		 *  by a slot are marked as private, in which case the noslot
>>> +		 *  range will also result in -ENOENT.
>>> +		 *
>>> +		 *  So allow both errors for now, but in the future it would be
>>> +		 *  good to distinguish between these cases to tighten up the
>>> +		 *  error-checking.
>>> +		 */
>>> +		TEST_ASSERT(expect_fail ? !ret :
>>> +			    (ret && (save_errno == EFAULT || save_errno == ENOENT)),
>>> +			    "[EXPECT %s] KVM_PRE_FAULT_MEMORY",
>>> +			    expect_fail ? "FAIL" : "PASS");
>>> +	}
>>> +}
>>> +
>>> +static void pre_fault_memory(struct kvm_vcpu *vcpu, u64 gpa,
>>> +			     u64 size, u64 left)
>>> +{
>>> +	__pre_fault_memory(vcpu, gpa, size, left, false);
>>> +}
>>> +
>>> +static void pre_fault_memory_negative(struct kvm_vcpu *vcpu, u64 gpa,
>>> +				      u64 size, u64 left)
>>> +{
>>> +	__pre_fault_memory(vcpu, gpa, size, left, true);
>>> +}
>>> +
>>> +static void pre_fault_memory_snp(struct kvm_vcpu *vcpu, struct kvm_vm *vm,
>>> +				 bool private, enum prefault_snp_test_type p_type)
>>> +{
>>> +	if (p_type == PREFAULT_SHARED_BEFORE_FINALIZING)
>>> +		pre_fault_memory_negative(vcpu, TEST_GPA, SZ_2M, 0);
>>> +
>>> +	snp_vm_launch_start(vm, SNP_POLICY);
>>> +
>>> +	if (p_type == PREFAULT_SHARED_BEFORE_FINALIZING)
>>> +		pre_fault_memory_negative(vcpu, TEST_GPA, SZ_2M, 0);
>>> +
>>> +	if (private) {
>>> +		/*
>>> +		 * Make sure when pages are pre-faulted later after
>>> +		 * finalization they are treated the same as a private
>>> +		 * access by the guest so that the expected gmem
>>> +		 * backing pages are used.
>>> +		 */
>>> +		vm_mem_set_private(vm, TEST_GPA, TEST_SIZE);
>>> +		if (p_type == PREFAULT_PRIVATE_BEFORE_FINALIZING)
>>> +			pre_fault_memory_negative(vcpu, TEST_GPA, SZ_2M, 0);
>>> +	} else {
>>> +		if (p_type == PREFAULT_SHARED_BEFORE_FINALIZING)
>>> +			pre_fault_memory_negative(vcpu, TEST_GPA, SZ_2M, 0);
>>> +	}
>>> +
>>> +	snp_vm_launch_update(vm);
>>> +
>>> +	if (p_type == PREFAULT_SHARED_BEFORE_FINALIZING)
>>> +		pre_fault_memory_negative(vcpu, TEST_GPA, SZ_2M, 0);
>>> +
>>> +	snp_vm_launch_finish(vm);
>>> +
>>> +	/*
>>> +	 * After finalization, pre-faulting either private or shared
>>> +	 * ranges should work regardless of whether the pages were
>>> +	 * encrypted as part of setting up initial guest state.
>>> +	 */
>>> +	if (p_type == PREFAULT_PRIVATE_SHARED_AFTER_FINALIZING) {
>>> +		pre_fault_memory(vcpu, TEST_GPA, SZ_2M, 0);
>>> +		pre_fault_memory(vcpu, TEST_GPA + SZ_2M, PAGE_SIZE * 2, PAGE_SIZE);
>>> +		pre_fault_memory(vcpu, TEST_GPA + TEST_SIZE, PAGE_SIZE, PAGE_SIZE);
>>> +	}
>>> +}
>>> +
>>> +static void pre_fault_memory_sev(unsigned long vm_type, struct kvm_vcpu *vcpu,
>>> +				 struct kvm_vm *vm)
>>> +{
>>> +	uint32_t policy = (vm_type == KVM_X86_SEV_ES_VM) ? SEV_POLICY_ES : 0;
>>> +
>>> +	pre_fault_memory(vcpu, TEST_GPA, SZ_2M, 0);
>>> +	pre_fault_memory(vcpu, TEST_GPA + SZ_2M, PAGE_SIZE * 2, PAGE_SIZE);
>>> +	pre_fault_memory(vcpu, TEST_GPA + TEST_SIZE, PAGE_SIZE, PAGE_SIZE);
>>> +
>>> +	sev_vm_launch(vm, policy);
>>> +
>>> +	pre_fault_memory(vcpu, TEST_GPA, SZ_2M, 0);
>>> +	pre_fault_memory(vcpu, TEST_GPA + SZ_2M, PAGE_SIZE * 2, PAGE_SIZE);
>>> +	pre_fault_memory(vcpu, TEST_GPA + TEST_SIZE, PAGE_SIZE, PAGE_SIZE);
>>> +
>>> +	sev_vm_launch_measure(vm, alloca(256));
>>> +
>>> +	pre_fault_memory(vcpu, TEST_GPA, SZ_2M, 0);
>>> +	pre_fault_memory(vcpu, TEST_GPA + SZ_2M, PAGE_SIZE * 2, PAGE_SIZE);
>>> +	pre_fault_memory(vcpu, TEST_GPA + TEST_SIZE, PAGE_SIZE, PAGE_SIZE);
>>> +
>>> +	sev_vm_launch_finish(vm);
>>> +
>>> +	pre_fault_memory(vcpu, TEST_GPA, SZ_2M, 0);
>>> +	pre_fault_memory(vcpu, TEST_GPA + SZ_2M, PAGE_SIZE * 2, PAGE_SIZE);
>>> +	pre_fault_memory(vcpu, TEST_GPA + TEST_SIZE, PAGE_SIZE, PAGE_SIZE);
>>> +}
>>> +
>>> +static void test_pre_fault_memory_sev(unsigned long vm_type, bool private,
>>> +				      enum prefault_snp_test_type p_type)
>>> +{
>>> +	struct kvm_vcpu *vcpu;
>>> +	struct kvm_vm *vm;
>>> +	struct ucall uc;
>>> +	int i;
>>> +
>>> +	vm = vm_sev_create_with_one_vcpu(vm_type, guest_code_sev, &vcpu);
>>> +
>>> +	vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS,
>>> +				    TEST_GPA, TEST_SLOT, TEST_NPAGES,
>>> +				    (vm_type == KVM_X86_SNP_VM) ? KVM_MEM_GUEST_MEMFD : 0);
>>> +
>>> +	/*
>>> +	 * Make sure guest page table is in agreement with what pages will be
>>> +	 * initially encrypted by the ASP.
>>> +	 */
>>> +	if (private)
>>> +		vm_mem_set_protected(vm, TEST_SLOT, TEST_GPA, TEST_NPAGES);
>>> +
>>> +	virt_map(vm, TEST_GVA, TEST_GPA, TEST_NPAGES);
>>> +
>>> +	/*
>>> +	 * Populate the pages to compare data read from the guest
>>> +	 * Populate the first half with data and second half as all zeros.
>>> +	 */
>>> +	for (i = 0; i < TEST_NPAGES; i++) {
>>> +		uint64_t *hva = addr_gva2hva(vm, TEST_GVA + i * PAGE_SIZE);
>>> +
>>> +		if (i < TEST_NPAGES / 2)
>>> +			*hva = i + 1;
>>> +		else
>>> +			*hva = 0;
>>> +	}
>>> +
>>> +	if (vm_type == KVM_X86_SNP_VM)
>>> +		pre_fault_memory_snp(vcpu, vm, private, p_type);
>>> +	else
>>> +		pre_fault_memory_sev(vm_type, vcpu, vm);
>>> +
>>> +	vcpu_run(vcpu);
>>> +
>>> +	if (vm->type == KVM_X86_SEV_ES_VM || vm->type == KVM_X86_SNP_VM) {
>>> +		TEST_ASSERT(vcpu->run->exit_reason == KVM_EXIT_SYSTEM_EVENT,
>>> +			    "Wanted SYSTEM_EVENT, got %s",
>>> +			    exit_reason_str(vcpu->run->exit_reason));
>>> +		TEST_ASSERT_EQ(vcpu->run->system_event.type, KVM_SYSTEM_EVENT_SEV_TERM);
>>> +		TEST_ASSERT_EQ(vcpu->run->system_event.ndata, 1);
>>> +		TEST_ASSERT_EQ(vcpu->run->system_event.data[0], GHCB_MSR_TERM_REQ);
>>> +		goto out;
>>> +	}
>>> +
>>> +	switch (get_ucall(vcpu, &uc)) {
>>> +	case UCALL_DONE:
>>> +		break;
>>> +	case UCALL_ABORT:
>>> +		REPORT_GUEST_ASSERT(uc);
>>> +	default:
>>> +		TEST_FAIL("Unexpected exit: %s",
>>> +			  exit_reason_str(vcpu->run->exit_reason));
>>> +	}
>>> +
>>> +out:
>>> +	kvm_vm_free(vm);
>>> +}
>>> +
>>> +static void test_pre_fault_memory(unsigned long vm_type, bool private)
>>> +{
>>> +	int pt;
>>> +
>>> +	if (vm_type && !(kvm_check_cap(KVM_CAP_VM_TYPES) & BIT(vm_type))) {
>>> +		pr_info("Skipping tests for vm_type 0x%lx\n", vm_type);
>>> +		return;
>>> +	}
>>> +
>>> +	switch (vm_type) {
>>> +	case KVM_X86_SEV_VM:
>>> +	case KVM_X86_SEV_ES_VM:
>>> +		test_pre_fault_memory_sev(vm_type, private, NO_PREFAULT_TYPE);
>>> +		break;
>>> +	case KVM_X86_SNP_VM:
>>> +		for (pt = 0; pt <= PREFAULT_PRIVATE_SHARED_AFTER_FINALIZING; pt++)
>>> +			test_pre_fault_memory_sev(vm_type, private, pt);
>>> +		break;
>>> +	default:
>>> +		abort();
>>> +	}
>>> +}
>>> +
>>> +int main(int argc, char *argv[])
>>> +{
>>> +	TEST_REQUIRE(kvm_check_cap(KVM_CAP_PRE_FAULT_MEMORY));
>>> +
>>> +	test_pre_fault_memory(KVM_X86_SEV_VM, false);
>>> +	test_pre_fault_memory(KVM_X86_SEV_VM, true);
>>> +	test_pre_fault_memory(KVM_X86_SEV_ES_VM, false);
>>> +	test_pre_fault_memory(KVM_X86_SEV_ES_VM, true);
>>> +	test_pre_fault_memory(KVM_X86_SNP_VM, false);
>>> +	test_pre_fault_memory(KVM_X86_SNP_VM, true);
>>> +
>>> +	return 0;
>>> +}
>>
diff mbox series

Patch

diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index 48d32c5aa3eb..65d19b277b06 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -129,6 +129,7 @@  TEST_GEN_PROGS_x86_64 += x86_64/amx_test
 TEST_GEN_PROGS_x86_64 += x86_64/max_vcpuid_cap_test
 TEST_GEN_PROGS_x86_64 += x86_64/triple_fault_event_test
 TEST_GEN_PROGS_x86_64 += x86_64/recalc_apic_map_test
+TEST_GEN_PROGS_x86_64 += x86_64/coco_pre_fault_memory_test
 TEST_GEN_PROGS_x86_64 += access_tracking_perf_test
 TEST_GEN_PROGS_x86_64 += demand_paging_test
 TEST_GEN_PROGS_x86_64 += dirty_log_test
diff --git a/tools/testing/selftests/kvm/x86_64/coco_pre_fault_memory_test.c b/tools/testing/selftests/kvm/x86_64/coco_pre_fault_memory_test.c
new file mode 100644
index 000000000000..e16fe185fb5a
--- /dev/null
+++ b/tools/testing/selftests/kvm/x86_64/coco_pre_fault_memory_test.c
@@ -0,0 +1,314 @@ 
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/sizes.h>
+
+#include <test_util.h>
+#include <kvm_util.h>
+#include <processor.h>
+#include "sev.h"
+
+/* Arbitrarily chosen values */
+#define TEST_SIZE		(SZ_2M + PAGE_SIZE)
+#define TEST_NPAGES		(TEST_SIZE / PAGE_SIZE)
+#define TEST_SLOT		10
+#define TEST_GPA		0x100000000ul
+#define TEST_GVA		0x100000000ul
+
+enum prefault_snp_test_type {
+	/* Skip pre-faulting tests. */
+	NO_PREFAULT_TYPE = 0,
+	/*
+	 * Issue KVM_PRE_FAULT_MEMORY for GFNs mapping non-private memory
+	 * before finalizing the initial guest contents (e.g. via
+	 * KVM_SEV_SNP_LAUNCH_FINISH for SNP guests).
+	 *
+	 * This should result in failure since KVM explicitly disallows
+	 * KVM_PRE_FAULT_MEMORY from being issued prior to finalizing the
+	 * initial guest contents.
+	 */
+	PREFAULT_SHARED_BEFORE_FINALIZING = 0,
+	/*
+	 * Issue KVM_PRE_FAULT_MEMORY for GFNs mapping private memory
+	 * before finalizing the initial guest contents (e.g. via
+	 * KVM_SEV_SNP_LAUNCH_FINISH for SNP guests).
+	 *
+	 * This should result in failure since KVM explicitly disallows
+	 * KVM_PRE_FAULT_MEMORY from being issued prior to finalizing the
+	 * initial guest contents.
+	 */
+	PREFAULT_PRIVATE_BEFORE_FINALIZING,
+	/*
+	 * Issue KVM_PRE_FAULT_MEMORY for GFNs mapping shared/private
+	 * memory after finalizing the initial guest contents
+	 * (e.g. via * KVM_SEV_SNP_LAUNCH_FINISH for SNP guests).
+	 *
+	 * This should succeed since pre-faulting is supported for both
+	 * non-private/private memory once the guest contents are finalized.
+	 */
+	PREFAULT_PRIVATE_SHARED_AFTER_FINALIZING
+};
+
+static void guest_code_sev(void)
+{
+	int i;
+
+	GUEST_ASSERT(rdmsr(MSR_AMD64_SEV) & MSR_AMD64_SEV_ENABLED);
+
+	for (i = 0; i < TEST_NPAGES; i++) {
+		uint64_t *src = (uint64_t *)(TEST_GVA + i * PAGE_SIZE);
+		uint64_t val = *src;
+
+		/* Validate the data stored in the pages */
+		if ((i < TEST_NPAGES / 2 && val != i + 1) ||
+		    (i >= TEST_NPAGES / 2 && val != 0)) {
+			GUEST_FAIL("Inconsistent view of memory values in guest");
+		}
+	}
+
+	if (rdmsr(MSR_AMD64_SEV) & MSR_AMD64_SEV_ES_ENABLED) {
+		wrmsr(MSR_AMD64_SEV_ES_GHCB, GHCB_MSR_TERM_REQ);
+		__asm__ __volatile__("rep; vmmcall");
+		GUEST_FAIL("This should be unreachable.");
+	}
+
+	GUEST_DONE();
+}
+
+static void __pre_fault_memory(struct kvm_vcpu *vcpu, u64 gpa, u64 size,
+			       u64 left, bool expect_fail)
+{
+	struct kvm_pre_fault_memory range = {
+		.gpa = gpa,
+		.size = size,
+		.flags = 0,
+	};
+	int ret, save_errno;
+	u64 prev;
+
+	do {
+		prev = range.size;
+		ret = __vcpu_ioctl(vcpu, KVM_PRE_FAULT_MEMORY, &range);
+		save_errno = errno;
+		TEST_ASSERT((range.size < prev) ^ (ret < 0),
+			    "%sexpecting range.size to change on %s",
+			    ret < 0 ? "not " : "",
+			    ret < 0 ? "failure" : "success");
+	} while (ret >= 0 ? range.size : save_errno == EINTR);
+
+	TEST_ASSERT(expect_fail ? !(range.size == left) : (range.size == left),
+		    "[EXPECT %s] completed with %lld bytes left, expected %" PRId64,
+		    expect_fail ? "FAIL" : "PASS",
+		    range.size, left);
+
+	if (left == 0) {
+		TEST_ASSERT(expect_fail ? ret : !ret,
+			    "[EXPECT %s] KVM_PRE_FAULT_MEMORY",
+			    expect_fail ? "FAIL" : "PASS");
+	} else {
+		/*
+		 * For shared memory, no memory slot causes RET_PF_EMULATE. It
+		 * results in -ENOENT.
+		 *
+		 * For private memory, no memory slot is an error case returning
+		 * -EFAULT, but it also possible the only the GPA ranges backed
+		 *  by a slot are marked as private, in which case the noslot
+		 *  range will also result in -ENOENT.
+		 *
+		 *  So allow both errors for now, but in the future it would be
+		 *  good to distinguish between these cases to tighten up the
+		 *  error-checking.
+		 */
+		TEST_ASSERT(expect_fail ? !ret :
+			    (ret && (save_errno == EFAULT || save_errno == ENOENT)),
+			    "[EXPECT %s] KVM_PRE_FAULT_MEMORY",
+			    expect_fail ? "FAIL" : "PASS");
+	}
+}
+
+static void pre_fault_memory(struct kvm_vcpu *vcpu, u64 gpa,
+			     u64 size, u64 left)
+{
+	__pre_fault_memory(vcpu, gpa, size, left, false);
+}
+
+static void pre_fault_memory_negative(struct kvm_vcpu *vcpu, u64 gpa,
+				      u64 size, u64 left)
+{
+	__pre_fault_memory(vcpu, gpa, size, left, true);
+}
+
+static void pre_fault_memory_snp(struct kvm_vcpu *vcpu, struct kvm_vm *vm,
+				 bool private, enum prefault_snp_test_type p_type)
+{
+	if (p_type == PREFAULT_SHARED_BEFORE_FINALIZING)
+		pre_fault_memory_negative(vcpu, TEST_GPA, SZ_2M, 0);
+
+	snp_vm_launch_start(vm, SNP_POLICY);
+
+	if (p_type == PREFAULT_SHARED_BEFORE_FINALIZING)
+		pre_fault_memory_negative(vcpu, TEST_GPA, SZ_2M, 0);
+
+	if (private) {
+		/*
+		 * Make sure when pages are pre-faulted later after
+		 * finalization they are treated the same as a private
+		 * access by the guest so that the expected gmem
+		 * backing pages are used.
+		 */
+		vm_mem_set_private(vm, TEST_GPA, TEST_SIZE);
+		if (p_type == PREFAULT_PRIVATE_BEFORE_FINALIZING)
+			pre_fault_memory_negative(vcpu, TEST_GPA, SZ_2M, 0);
+	} else {
+		if (p_type == PREFAULT_SHARED_BEFORE_FINALIZING)
+			pre_fault_memory_negative(vcpu, TEST_GPA, SZ_2M, 0);
+	}
+
+	snp_vm_launch_update(vm);
+
+	if (p_type == PREFAULT_SHARED_BEFORE_FINALIZING)
+		pre_fault_memory_negative(vcpu, TEST_GPA, SZ_2M, 0);
+
+	snp_vm_launch_finish(vm);
+
+	/*
+	 * After finalization, pre-faulting either private or shared
+	 * ranges should work regardless of whether the pages were
+	 * encrypted as part of setting up initial guest state.
+	 */
+	if (p_type == PREFAULT_PRIVATE_SHARED_AFTER_FINALIZING) {
+		pre_fault_memory(vcpu, TEST_GPA, SZ_2M, 0);
+		pre_fault_memory(vcpu, TEST_GPA + SZ_2M, PAGE_SIZE * 2, PAGE_SIZE);
+		pre_fault_memory(vcpu, TEST_GPA + TEST_SIZE, PAGE_SIZE, PAGE_SIZE);
+	}
+}
+
+static void pre_fault_memory_sev(unsigned long vm_type, struct kvm_vcpu *vcpu,
+				 struct kvm_vm *vm)
+{
+	uint32_t policy = (vm_type == KVM_X86_SEV_ES_VM) ? SEV_POLICY_ES : 0;
+
+	pre_fault_memory(vcpu, TEST_GPA, SZ_2M, 0);
+	pre_fault_memory(vcpu, TEST_GPA + SZ_2M, PAGE_SIZE * 2, PAGE_SIZE);
+	pre_fault_memory(vcpu, TEST_GPA + TEST_SIZE, PAGE_SIZE, PAGE_SIZE);
+
+	sev_vm_launch(vm, policy);
+
+	pre_fault_memory(vcpu, TEST_GPA, SZ_2M, 0);
+	pre_fault_memory(vcpu, TEST_GPA + SZ_2M, PAGE_SIZE * 2, PAGE_SIZE);
+	pre_fault_memory(vcpu, TEST_GPA + TEST_SIZE, PAGE_SIZE, PAGE_SIZE);
+
+	sev_vm_launch_measure(vm, alloca(256));
+
+	pre_fault_memory(vcpu, TEST_GPA, SZ_2M, 0);
+	pre_fault_memory(vcpu, TEST_GPA + SZ_2M, PAGE_SIZE * 2, PAGE_SIZE);
+	pre_fault_memory(vcpu, TEST_GPA + TEST_SIZE, PAGE_SIZE, PAGE_SIZE);
+
+	sev_vm_launch_finish(vm);
+
+	pre_fault_memory(vcpu, TEST_GPA, SZ_2M, 0);
+	pre_fault_memory(vcpu, TEST_GPA + SZ_2M, PAGE_SIZE * 2, PAGE_SIZE);
+	pre_fault_memory(vcpu, TEST_GPA + TEST_SIZE, PAGE_SIZE, PAGE_SIZE);
+}
+
+static void test_pre_fault_memory_sev(unsigned long vm_type, bool private,
+				      enum prefault_snp_test_type p_type)
+{
+	struct kvm_vcpu *vcpu;
+	struct kvm_vm *vm;
+	struct ucall uc;
+	int i;
+
+	vm = vm_sev_create_with_one_vcpu(vm_type, guest_code_sev, &vcpu);
+
+	vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS,
+				    TEST_GPA, TEST_SLOT, TEST_NPAGES,
+				    (vm_type == KVM_X86_SNP_VM) ? KVM_MEM_GUEST_MEMFD : 0);
+
+	/*
+	 * Make sure guest page table is in agreement with what pages will be
+	 * initially encrypted by the ASP.
+	 */
+	if (private)
+		vm_mem_set_protected(vm, TEST_SLOT, TEST_GPA, TEST_NPAGES);
+
+	virt_map(vm, TEST_GVA, TEST_GPA, TEST_NPAGES);
+
+	/*
+	 * Populate the pages to compare data read from the guest
+	 * Populate the first half with data and second half as all zeros.
+	 */
+	for (i = 0; i < TEST_NPAGES; i++) {
+		uint64_t *hva = addr_gva2hva(vm, TEST_GVA + i * PAGE_SIZE);
+
+		if (i < TEST_NPAGES / 2)
+			*hva = i + 1;
+		else
+			*hva = 0;
+	}
+
+	if (vm_type == KVM_X86_SNP_VM)
+		pre_fault_memory_snp(vcpu, vm, private, p_type);
+	else
+		pre_fault_memory_sev(vm_type, vcpu, vm);
+
+	vcpu_run(vcpu);
+
+	if (vm->type == KVM_X86_SEV_ES_VM || vm->type == KVM_X86_SNP_VM) {
+		TEST_ASSERT(vcpu->run->exit_reason == KVM_EXIT_SYSTEM_EVENT,
+			    "Wanted SYSTEM_EVENT, got %s",
+			    exit_reason_str(vcpu->run->exit_reason));
+		TEST_ASSERT_EQ(vcpu->run->system_event.type, KVM_SYSTEM_EVENT_SEV_TERM);
+		TEST_ASSERT_EQ(vcpu->run->system_event.ndata, 1);
+		TEST_ASSERT_EQ(vcpu->run->system_event.data[0], GHCB_MSR_TERM_REQ);
+		goto out;
+	}
+
+	switch (get_ucall(vcpu, &uc)) {
+	case UCALL_DONE:
+		break;
+	case UCALL_ABORT:
+		REPORT_GUEST_ASSERT(uc);
+	default:
+		TEST_FAIL("Unexpected exit: %s",
+			  exit_reason_str(vcpu->run->exit_reason));
+	}
+
+out:
+	kvm_vm_free(vm);
+}
+
+static void test_pre_fault_memory(unsigned long vm_type, bool private)
+{
+	int pt;
+
+	if (vm_type && !(kvm_check_cap(KVM_CAP_VM_TYPES) & BIT(vm_type))) {
+		pr_info("Skipping tests for vm_type 0x%lx\n", vm_type);
+		return;
+	}
+
+	switch (vm_type) {
+	case KVM_X86_SEV_VM:
+	case KVM_X86_SEV_ES_VM:
+		test_pre_fault_memory_sev(vm_type, private, NO_PREFAULT_TYPE);
+		break;
+	case KVM_X86_SNP_VM:
+		for (pt = 0; pt <= PREFAULT_PRIVATE_SHARED_AFTER_FINALIZING; pt++)
+			test_pre_fault_memory_sev(vm_type, private, pt);
+		break;
+	default:
+		abort();
+	}
+}
+
+int main(int argc, char *argv[])
+{
+	TEST_REQUIRE(kvm_check_cap(KVM_CAP_PRE_FAULT_MEMORY));
+
+	test_pre_fault_memory(KVM_X86_SEV_VM, false);
+	test_pre_fault_memory(KVM_X86_SEV_VM, true);
+	test_pre_fault_memory(KVM_X86_SEV_ES_VM, false);
+	test_pre_fault_memory(KVM_X86_SEV_ES_VM, true);
+	test_pre_fault_memory(KVM_X86_SNP_VM, false);
+	test_pre_fault_memory(KVM_X86_SNP_VM, true);
+
+	return 0;
+}