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DIR:OUT; SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 20 Jun 2022 23:04:10.1129 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: bc7f4d59-db38-4cc8-9abe-08da53112f74 X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d; Ip=[165.204.84.17]; Helo=[SATLEXMB04.amd.com] X-MS-Exchange-CrossTenant-AuthSource: DM6NAM11FT044.eop-nam11.prod.protection.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: BN6PR1201MB2546 Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org From: Brijesh Singh When SEV-SNP is enabled globally, a write from the host goes through the RMP check. If the hardware encounters the check failure, then it raises the #PF (with RMP set). Dump the RMP entry at the faulting pfn to help the debug. Signed-off-by: Brijesh Singh --- arch/x86/include/asm/sev.h | 7 +++++++ arch/x86/kernel/sev.c | 43 ++++++++++++++++++++++++++++++++++++++ arch/x86/mm/fault.c | 17 +++++++++++---- include/linux/sev.h | 2 ++ 4 files changed, 65 insertions(+), 4 deletions(-) diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h index 6ab872311544..c0c4df817159 100644 --- a/arch/x86/include/asm/sev.h +++ b/arch/x86/include/asm/sev.h @@ -113,6 +113,11 @@ struct __packed rmpentry { #define rmpentry_assigned(x) ((x)->info.assigned) #define rmpentry_pagesize(x) ((x)->info.pagesize) +#define rmpentry_vmsa(x) ((x)->info.vmsa) +#define rmpentry_asid(x) ((x)->info.asid) +#define rmpentry_validated(x) ((x)->info.validated) +#define rmpentry_gpa(x) ((unsigned long)(x)->info.gpa) +#define rmpentry_immutable(x) ((x)->info.immutable) #define RMPADJUST_VMSA_PAGE_BIT BIT(16) @@ -205,6 +210,7 @@ void snp_set_wakeup_secondary_cpu(void); bool snp_init(struct boot_params *bp); void snp_abort(void); int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, unsigned long *fw_err); +void dump_rmpentry(u64 pfn); #else static inline void sev_es_ist_enter(struct pt_regs *regs) { } static inline void sev_es_ist_exit(void) { } @@ -229,6 +235,7 @@ static inline int snp_issue_guest_request(u64 exit_code, struct snp_req_data *in { return -ENOTTY; } +static inline void dump_rmpentry(u64 pfn) {} #endif #endif diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c index 734cddd837f5..6640a639fffc 100644 --- a/arch/x86/kernel/sev.c +++ b/arch/x86/kernel/sev.c @@ -2414,6 +2414,49 @@ static struct rmpentry *__snp_lookup_rmpentry(u64 pfn, int *level) return entry; } +void dump_rmpentry(u64 pfn) +{ + unsigned long pfn_end; + struct rmpentry *e; + int level; + + e = __snp_lookup_rmpentry(pfn, &level); + if (!e) { + pr_alert("failed to read RMP entry pfn 0x%llx\n", pfn); + return; + } + + if (rmpentry_assigned(e)) { + pr_alert("RMPEntry paddr 0x%llx [assigned=%d immutable=%d pagesize=%d gpa=0x%lx" + " asid=%d vmsa=%d validated=%d]\n", pfn << PAGE_SHIFT, + rmpentry_assigned(e), rmpentry_immutable(e), rmpentry_pagesize(e), + rmpentry_gpa(e), rmpentry_asid(e), rmpentry_vmsa(e), + rmpentry_validated(e)); + return; + } + + /* + * If the RMP entry at the faulting pfn was not assigned, then we do not + * know what caused the RMP violation. To get some useful debug information, + * let iterate through the entire 2MB region, and dump the RMP entries if + * one of the bit in the RMP entry is set. + */ + pfn = pfn & ~(PTRS_PER_PMD - 1); + pfn_end = pfn + PTRS_PER_PMD; + + while (pfn < pfn_end) { + e = __snp_lookup_rmpentry(pfn, &level); + if (!e) + return; + + if (e->low || e->high) + pr_alert("RMPEntry paddr 0x%llx: [high=0x%016llx low=0x%016llx]\n", + pfn << PAGE_SHIFT, e->high, e->low); + pfn++; + } +} +EXPORT_SYMBOL_GPL(dump_rmpentry); + /* * Return 1 if the RMP entry is assigned, 0 if it exists but is not assigned, * and -errno if there is no corresponding RMP entry. diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index f5de9673093a..25896a6ba04a 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -34,6 +34,7 @@ #include /* kvm_handle_async_pf */ #include /* fixup_vdso_exception() */ #include +#include /* dump_rmpentry() */ #define CREATE_TRACE_POINTS #include @@ -290,7 +291,7 @@ static bool low_pfn(unsigned long pfn) return pfn < max_low_pfn; } -static void dump_pagetable(unsigned long address) +static void dump_pagetable(unsigned long address, bool show_rmpentry) { pgd_t *base = __va(read_cr3_pa()); pgd_t *pgd = &base[pgd_index(address)]; @@ -346,10 +347,11 @@ static int bad_address(void *p) return get_kernel_nofault(dummy, (unsigned long *)p); } -static void dump_pagetable(unsigned long address) +static void dump_pagetable(unsigned long address, bool show_rmpentry) { pgd_t *base = __va(read_cr3_pa()); pgd_t *pgd = base + pgd_index(address); + unsigned long pfn; p4d_t *p4d; pud_t *pud; pmd_t *pmd; @@ -367,6 +369,7 @@ static void dump_pagetable(unsigned long address) if (bad_address(p4d)) goto bad; + pfn = p4d_pfn(*p4d); pr_cont("P4D %lx ", p4d_val(*p4d)); if (!p4d_present(*p4d) || p4d_large(*p4d)) goto out; @@ -375,6 +378,7 @@ static void dump_pagetable(unsigned long address) if (bad_address(pud)) goto bad; + pfn = pud_pfn(*pud); pr_cont("PUD %lx ", pud_val(*pud)); if (!pud_present(*pud) || pud_large(*pud)) goto out; @@ -383,6 +387,7 @@ static void dump_pagetable(unsigned long address) if (bad_address(pmd)) goto bad; + pfn = pmd_pfn(*pmd); pr_cont("PMD %lx ", pmd_val(*pmd)); if (!pmd_present(*pmd) || pmd_large(*pmd)) goto out; @@ -391,9 +396,13 @@ static void dump_pagetable(unsigned long address) if (bad_address(pte)) goto bad; + pfn = pte_pfn(*pte); pr_cont("PTE %lx", pte_val(*pte)); out: pr_cont("\n"); + + if (show_rmpentry) + dump_rmpentry(pfn); return; bad: pr_info("BAD\n"); @@ -579,7 +588,7 @@ show_fault_oops(struct pt_regs *regs, unsigned long error_code, unsigned long ad show_ldttss(&gdt, "TR", tr); } - dump_pagetable(address); + dump_pagetable(address, error_code & X86_PF_RMP); } static noinline void @@ -596,7 +605,7 @@ pgtable_bad(struct pt_regs *regs, unsigned long error_code, printk(KERN_ALERT "%s: Corrupted page table at address %lx\n", tsk->comm, address); - dump_pagetable(address); + dump_pagetable(address, false); if (__die("Bad pagetable", regs, error_code)) sig = 0; diff --git a/include/linux/sev.h b/include/linux/sev.h index 1a68842789e1..734b13a69c54 100644 --- a/include/linux/sev.h +++ b/include/linux/sev.h @@ -16,6 +16,7 @@ int snp_lookup_rmpentry(u64 pfn, int *level); int psmash(u64 pfn); int rmp_make_private(u64 pfn, u64 gpa, enum pg_level level, int asid, bool immutable); int rmp_make_shared(u64 pfn, enum pg_level level); +void dump_rmpentry(u64 pfn); #else static inline int snp_lookup_rmpentry(u64 pfn, int *level) { return 0; } static inline int psmash(u64 pfn) { return -ENXIO; } @@ -25,6 +26,7 @@ static inline int rmp_make_private(u64 pfn, u64 gpa, enum pg_level level, int as return -ENODEV; } static inline int rmp_make_shared(u64 pfn, enum pg_level level) { return -ENODEV; } +static inline void dump_rmpentry(u64 pfn) { } #endif /* CONFIG_AMD_MEM_ENCRYPT */ #endif /* __LINUX_SEV_H */