| Message ID | 20210820155918.7518-10-brijesh.singh@amd.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Delegated to: | Herbert Xu |
| Headers | show |
| Series | Add AMD Secure Nested Paging (SEV-SNP) Hypervisor Support | expand |
On Fri, Aug 20, 2021 at 10:58:42AM -0500, Brijesh Singh wrote: > 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 <brijesh.singh@amd.com> > --- > 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 92ced9626e95..569294f687e6 100644 > --- a/arch/x86/include/asm/sev.h > +++ b/arch/x86/include/asm/sev.h > @@ -106,6 +106,11 @@ 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) If some of those accessors are going to be used only in dump_rmpentry(), then you don't really need them. > > #define RMPADJUST_VMSA_PAGE_BIT BIT(16) > > @@ -165,6 +170,7 @@ void __init snp_prep_memory(unsigned long paddr, unsigned int sz, enum psc_op op > void snp_set_memory_shared(unsigned long vaddr, unsigned int npages); > void snp_set_memory_private(unsigned long vaddr, unsigned int npages); > void snp_set_wakeup_secondary_cpu(void); > +void dump_rmpentry(u64 pfn); > #ifdef __BOOT_COMPRESSED > bool sev_snp_enabled(void); > #else > @@ -188,6 +194,7 @@ static inline void snp_set_memory_shared(unsigned long vaddr, unsigned int npage > static inline void snp_set_memory_private(unsigned long vaddr, unsigned int npages) { } > static inline void snp_set_wakeup_secondary_cpu(void) { } > static inline void sev_snp_cpuid_init(struct boot_params *bp) { } > +static inline void dump_rmpentry(u64 pfn) {} > #ifdef __BOOT_COMPRESSED > static inline bool sev_snp_enabled { return false; } > #else > diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c > index bad41deb8335..8b3e83e50468 100644 > --- a/arch/x86/kernel/sev.c > +++ b/arch/x86/kernel/sev.c > @@ -2404,6 +2404,49 @@ static struct rmpentry *__snp_lookup_rmpentry(u64 pfn, int *level) > return entry; > } > > +void dump_rmpentry(u64 pfn) snp_dump_rmpentry() > +{ > + 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, WARNING: quoted string split across lines #174: FILE: arch/x86/kernel/sev.c:2421: + 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; return? You mean "continue;" ? > + > + 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); Why is that exported? Some module will be calling it too? > + > /* > * 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 f2d543b92f43..9cd33169dfb5 100644 > --- a/arch/x86/mm/fault.c > +++ b/arch/x86/mm/fault.c > @@ -33,6 +33,7 @@ > #include <asm/pgtable_areas.h> /* VMALLOC_START, ... */ > #include <asm/kvm_para.h> /* kvm_handle_async_pf */ > #include <asm/vdso.h> /* fixup_vdso_exception() */ > +#include <asm/sev.h> /* dump_rmpentry() */ > > #define CREATE_TRACE_POINTS > #include <asm/trace/exceptions.h> > @@ -289,7 +290,7 @@ 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) I think passing in error_code and testing X86_PF_RMP inside should make this a bit more palatable than simply "grafting" SNP-specific functionality to generic paths. Thx.
diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h index 92ced9626e95..569294f687e6 100644 --- a/arch/x86/include/asm/sev.h +++ b/arch/x86/include/asm/sev.h @@ -106,6 +106,11 @@ 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) @@ -165,6 +170,7 @@ void __init snp_prep_memory(unsigned long paddr, unsigned int sz, enum psc_op op void snp_set_memory_shared(unsigned long vaddr, unsigned int npages); void snp_set_memory_private(unsigned long vaddr, unsigned int npages); void snp_set_wakeup_secondary_cpu(void); +void dump_rmpentry(u64 pfn); #ifdef __BOOT_COMPRESSED bool sev_snp_enabled(void); #else @@ -188,6 +194,7 @@ static inline void snp_set_memory_shared(unsigned long vaddr, unsigned int npage static inline void snp_set_memory_private(unsigned long vaddr, unsigned int npages) { } static inline void snp_set_wakeup_secondary_cpu(void) { } static inline void sev_snp_cpuid_init(struct boot_params *bp) { } +static inline void dump_rmpentry(u64 pfn) {} #ifdef __BOOT_COMPRESSED static inline bool sev_snp_enabled { return false; } #else diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c index bad41deb8335..8b3e83e50468 100644 --- a/arch/x86/kernel/sev.c +++ b/arch/x86/kernel/sev.c @@ -2404,6 +2404,49 @@ 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 f2d543b92f43..9cd33169dfb5 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -33,6 +33,7 @@ #include <asm/pgtable_areas.h> /* VMALLOC_START, ... */ #include <asm/kvm_para.h> /* kvm_handle_async_pf */ #include <asm/vdso.h> /* fixup_vdso_exception() */ +#include <asm/sev.h> /* dump_rmpentry() */ #define CREATE_TRACE_POINTS #include <asm/trace/exceptions.h> @@ -289,7 +290,7 @@ 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)]; @@ -345,10 +346,11 @@ 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; @@ -366,6 +368,7 @@ 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; @@ -374,6 +377,7 @@ 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; @@ -382,6 +386,7 @@ 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; @@ -390,9 +395,13 @@ 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"); @@ -578,7 +587,7 @@ 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 @@ -595,7 +604,7 @@ 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 */
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 <brijesh.singh@amd.com> --- 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(-)