diff mbox series

[v3,6/7] KVM: SVM: Add support to initialize SEV/SNP functionality in KVM

Message ID 14f97f58d6150c6784909261db7f9a05d8d32566.1735931639.git.ashish.kalra@amd.com
State New
Headers show
Series Move initializing SEV/SNP functionality to KVM | expand

Commit Message

Kalra, Ashish Jan. 3, 2025, 8:01 p.m. UTC 
From: Ashish Kalra <ashish.kalra@amd.com>

Remove platform initialization of SEV/SNP from PSP driver probe time and
move it to KVM module load time so that KVM can do SEV/SNP platform
initialization explicitly if it actually wants to use SEV/SNP
functionality.

With this patch, KVM will explicitly call into the PSP driver at load time
to initialize SEV/SNP by default but this behavior can be altered with KVM
module parameters to not do SEV/SNP platform initialization at module load
time if required. Additionally SEV/SNP platform shutdown is invoked during
KVM module unload time.

Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
---
 arch/x86/kvm/svm/sev.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

Comments

Kalra, Ashish Jan. 7, 2025, 8:56 p.m. UTC | #1 
+Adding Peter

On 1/7/2025 12:34 PM, Kalra, Ashish wrote:
> 
> 
> On 1/7/2025 10:42 AM, Tom Lendacky wrote:
>> On 1/3/25 14:01, Ashish Kalra wrote:
>>> From: Ashish Kalra <ashish.kalra@amd.com>
>>>
>>> Remove platform initialization of SEV/SNP from PSP driver probe time and
>>
>> Actually, you're not removing it, yet...
>>
>>> move it to KVM module load time so that KVM can do SEV/SNP platform
>>> initialization explicitly if it actually wants to use SEV/SNP
>>> functionality.
>>>
>>> With this patch, KVM will explicitly call into the PSP driver at load time
>>> to initialize SEV/SNP by default but this behavior can be altered with KVM
>>> module parameters to not do SEV/SNP platform initialization at module load
>>> time if required. Additionally SEV/SNP platform shutdown is invoked during
>>> KVM module unload time.
>>>
>>> Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
>>> ---
>>>  arch/x86/kvm/svm/sev.c | 15 ++++++++++++++-
>>>  1 file changed, 14 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
>>> index 943bd074a5d3..0dc8294582c6 100644
>>> --- a/arch/x86/kvm/svm/sev.c
>>> +++ b/arch/x86/kvm/svm/sev.c
>>> @@ -444,7 +444,6 @@ static int __sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp,
>>>  	if (ret)
>>>  		goto e_no_asid;
>>>  
>>> -	init_args.probe = false;
>>>  	ret = sev_platform_init(&init_args);
>>>  	if (ret)
>>>  		goto e_free;
>>> @@ -2953,6 +2952,7 @@ void __init sev_set_cpu_caps(void)
>>>  void __init sev_hardware_setup(void)
>>>  {
>>>  	unsigned int eax, ebx, ecx, edx, sev_asid_count, sev_es_asid_count;
>>> +	struct sev_platform_init_args init_args = {0};
>>
>> Will this cause issues if KVM is built-in and INIT_EX is being used
>> (init_ex_path ccp parameter)? The probe parameter is used for
>> initialization done before the filesystem is available.
>>
> 
> Yes, this will cause issues if KVM is builtin and INIT_EX is being used,
> but my question is how will INIT_EX be used when we move SEV INIT
> to KVM ?
> 
> If we continue to use the probe field here and also continue to support
> psp_init_on_probe module parameter for CCP, how will SEV INIT_EX be
> invoked ? 
> 
> How is SEV INIT_EX invoked in PSP driver currently if psp_init_on_probe
> parameter is set to false ?
> 
> The KVM path to invoke sev_platform_init() when a SEV VM is being launched 
> cannot be used because QEMU checks for SEV to be initialized before
> invoking this code path to launch the guest.

Peter, I believe that you have a different path to test SEV INIT_EX which 
won't be affected by this QEMU check. 

I will add back the probe field and psp_init_on_probe parameter for the 
CCP module, but i will need your help to test and verify if SEV INIT_EX
works with this patch-set.

Thanks,
Ashish

> 
>> Thanks,
>> Tom
>>
>>>  	bool sev_snp_supported = false;
>>>  	bool sev_es_supported = false;
>>>  	bool sev_supported = false;
>>> @@ -3069,6 +3069,16 @@ void __init sev_hardware_setup(void)
>>>  	sev_supported_vmsa_features = 0;
>>>  	if (sev_es_debug_swap_enabled)
>>>  		sev_supported_vmsa_features |= SVM_SEV_FEAT_DEBUG_SWAP;
>>> +
>>> +	if (!sev_enabled)
>>> +		return;
>>> +
>>> +	/*
>>> +	 * NOTE: Always do SNP INIT regardless of sev_snp_supported
>>> +	 * as SNP INIT has to be done to launch legacy SEV/SEV-ES
>>> +	 * VMs in case SNP is enabled system-wide.
>>> +	 */
>>> +	sev_platform_init(&init_args);
>>>  }
>>>  
>>>  void sev_hardware_unsetup(void)
>>> @@ -3084,6 +3094,9 @@ void sev_hardware_unsetup(void)
>>>  
>>>  	misc_cg_set_capacity(MISC_CG_RES_SEV, 0);
>>>  	misc_cg_set_capacity(MISC_CG_RES_SEV_ES, 0);
>>> +
>>> +	/* Do SEV and SNP Shutdown */
>>> +	sev_platform_shutdown();
>>>  }
>>>  
>>>  int sev_cpu_init(struct svm_cpu_data *sd)
>
diff mbox series

Patch

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 943bd074a5d3..0dc8294582c6 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -444,7 +444,6 @@  static int __sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp,
 	if (ret)
 		goto e_no_asid;
 
-	init_args.probe = false;
 	ret = sev_platform_init(&init_args);
 	if (ret)
 		goto e_free;
@@ -2953,6 +2952,7 @@  void __init sev_set_cpu_caps(void)
 void __init sev_hardware_setup(void)
 {
 	unsigned int eax, ebx, ecx, edx, sev_asid_count, sev_es_asid_count;
+	struct sev_platform_init_args init_args = {0};
 	bool sev_snp_supported = false;
 	bool sev_es_supported = false;
 	bool sev_supported = false;
@@ -3069,6 +3069,16 @@  void __init sev_hardware_setup(void)
 	sev_supported_vmsa_features = 0;
 	if (sev_es_debug_swap_enabled)
 		sev_supported_vmsa_features |= SVM_SEV_FEAT_DEBUG_SWAP;
+
+	if (!sev_enabled)
+		return;
+
+	/*
+	 * NOTE: Always do SNP INIT regardless of sev_snp_supported
+	 * as SNP INIT has to be done to launch legacy SEV/SEV-ES
+	 * VMs in case SNP is enabled system-wide.
+	 */
+	sev_platform_init(&init_args);
 }
 
 void sev_hardware_unsetup(void)
@@ -3084,6 +3094,9 @@  void sev_hardware_unsetup(void)
 
 	misc_cg_set_capacity(MISC_CG_RES_SEV, 0);
 	misc_cg_set_capacity(MISC_CG_RES_SEV_ES, 0);
+
+	/* Do SEV and SNP Shutdown */
+	sev_platform_shutdown();
 }
 
 int sev_cpu_init(struct svm_cpu_data *sd)