On 1/13/2023 4:56 PM, Alper Gun wrote:
On Wed, Dec 14, 2022 at 11:52 AM Michael Roth <michael.roth@xxxxxxx> wrote:
From: Brijesh Singh <brijesh.singh@xxxxxxx>
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@xxxxxxx>
Signed-off-by: Ashish Kalra <ashish.kalra@xxxxxxx>
Signed-off-by: Michael Roth <michael.roth@xxxxxxx>
---
arch/x86/include/asm/sev.h | 2 ++
arch/x86/kernel/sev.c | 43 ++++++++++++++++++++++++++++++++++++++
arch/x86/mm/fault.c | 7 ++++++-
3 files changed, 51 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
index 4eeedcaca593..2916f4150ac7 100644
--- a/arch/x86/include/asm/sev.h
+++ b/arch/x86/include/asm/sev.h
@@ -215,6 +215,7 @@ 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 sev_dump_rmpentry(u64 pfn);
#else
static inline void sev_es_ist_enter(struct pt_regs *regs) { }
static inline void sev_es_ist_exit(void) { }
@@ -247,6 +248,7 @@ 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 sev_dump_rmpentry(u64 pfn) {}
#endif
#endif
diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index e2b38c3551be..1dd1b36bdfea 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -2508,6 +2508,49 @@ static struct rmpentry *__snp_lookup_rmpentry(u64 pfn, int *level)
return entry;
}
+void sev_dump_rmpentry(u64 pfn)
+{
+ unsigned long pfn_end;
+ struct rmpentry *e;
+ int level;
+
+ e = __snp_lookup_rmpentry(pfn, &level);
+ if (!e) {
if (IS_ERR(e)) {
Yes, this needs to be fixed to IS_ERR(e)
+ pr_info("failed to read RMP entry pfn 0x%llx\n", pfn);
+ return;
+ }
+
+ if (rmpentry_assigned(e)) {
+ pr_info("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), e->info.immutable, rmpentry_pagesize(e),
+ (unsigned long)e->info.gpa, e->info.asid, e->info.vmsa,
+ e->info.validated);
+ return;
+ }
+
+ /*
+ * If the RMP entry at the faulting pfn was not assigned, then not sure
+ * what caused the RMP violation. To get some useful debug information,
+ * 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 (IS_ERR(e))
continue;
Again, this is correct, but then it should be :
if (IS_ERR(e)) {
pfn++;
continue;
}
Thanks,
Ashish
+
+ if (e->low || e->high)
+ pr_info("RMPEntry paddr 0x%llx: [high=0x%016llx low=0x%016llx]\n",
+ pfn << PAGE_SHIFT, e->high, e->low);
+ pfn++;
+ }
+}
+EXPORT_SYMBOL_GPL(sev_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 ded53879f98d..f2b16dcfbd9a 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -536,6 +536,8 @@ static void show_ldttss(const struct desc_ptr *gdt, const char *name, u16 index)
static void
show_fault_oops(struct pt_regs *regs, unsigned long error_code, unsigned long address)
{
+ unsigned long pfn;
+
if (!oops_may_print())
return;
@@ -608,7 +610,10 @@ show_fault_oops(struct pt_regs *regs, unsigned long error_code, unsigned long ad
show_ldttss(&gdt, "TR", tr);
}
- dump_pagetable(address);
+ pfn = dump_pagetable(address);
+
+ if (error_code & X86_PF_RMP)
+ sev_dump_rmpentry(pfn);
}
static noinline void
--
2.25.1
