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Message-ID: <170663196883.398.18077552190870723071.tip-bot2@tip-bot2>
Date: Tue, 30 Jan 2024 16:26:08 -0000
From: "tip-bot2 for Brijesh Singh" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Brijesh Singh <brijesh.singh@....com>, Ashish Kalra <ashish.kalra@....com>,
Michael Roth <michael.roth@....com>, "Borislav Petkov (AMD)" <bp@...en8.de>,
x86@...nel.org, linux-kernel@...r.kernel.org
Subject: [tip: x86/sev] x86/fault: Add helper for dumping RMP entries
The following commit has been merged into the x86/sev branch of tip:
Commit-ID: 1f568d36361b4891696280b719ca4b142db872ba
Gitweb: https://git.kernel.org/tip/1f568d36361b4891696280b719ca4b142db872ba
Author: Brijesh Singh <brijesh.singh@....com>
AuthorDate: Thu, 25 Jan 2024 22:11:07 -06:00
Committer: Borislav Petkov (AMD) <bp@...en8.de>
CommitterDate: Mon, 29 Jan 2024 17:26:30 +01:00
x86/fault: Add helper for dumping RMP entries
This information will be useful for debugging things like page faults
due to RMP access violations and RMPUPDATE failures.
[ mdr: move helper to standalone patch, rework dump logic as suggested
by Boris. ]
Signed-off-by: Brijesh Singh <brijesh.singh@....com>
Signed-off-by: Ashish Kalra <ashish.kalra@....com>
Signed-off-by: Michael Roth <michael.roth@....com>
Signed-off-by: Borislav Petkov (AMD) <bp@...en8.de>
Link: https://lore.kernel.org/r/20240126041126.1927228-8-michael.roth@amd.com
---
arch/x86/include/asm/sev.h | 2 +-
arch/x86/virt/svm/sev.c | 99 ++++++++++++++++++++++++++++++++----
2 files changed, 91 insertions(+), 10 deletions(-)
diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
index 01ce61b..2c53e3d 100644
--- a/arch/x86/include/asm/sev.h
+++ b/arch/x86/include/asm/sev.h
@@ -247,9 +247,11 @@ static inline u64 sev_get_status(void) { return 0; }
#ifdef CONFIG_KVM_AMD_SEV
bool snp_probe_rmptable_info(void);
int snp_lookup_rmpentry(u64 pfn, bool *assigned, int *level);
+void snp_dump_hva_rmpentry(unsigned long address);
#else
static inline bool snp_probe_rmptable_info(void) { return false; }
static inline int snp_lookup_rmpentry(u64 pfn, bool *assigned, int *level) { return -ENODEV; }
+static inline void snp_dump_hva_rmpentry(unsigned long address) {}
#endif
#endif
diff --git a/arch/x86/virt/svm/sev.c b/arch/x86/virt/svm/sev.c
index 7669b2f..c74266e 100644
--- a/arch/x86/virt/svm/sev.c
+++ b/arch/x86/virt/svm/sev.c
@@ -35,16 +35,21 @@
* Family 19h Model 01h, Rev B1 processor.
*/
struct rmpentry {
- u64 assigned : 1,
- pagesize : 1,
- immutable : 1,
- rsvd1 : 9,
- gpa : 39,
- asid : 10,
- vmsa : 1,
- validated : 1,
- rsvd2 : 1;
- u64 rsvd3;
+ union {
+ struct {
+ u64 assigned : 1,
+ pagesize : 1,
+ immutable : 1,
+ rsvd1 : 9,
+ gpa : 39,
+ asid : 10,
+ vmsa : 1,
+ validated : 1,
+ rsvd2 : 1;
+ };
+ u64 lo;
+ };
+ u64 hi;
} __packed;
/*
@@ -263,3 +268,77 @@ int snp_lookup_rmpentry(u64 pfn, bool *assigned, int *level)
return 0;
}
EXPORT_SYMBOL_GPL(snp_lookup_rmpentry);
+
+/*
+ * Dump the raw RMP entry for a particular PFN. These bits are documented in the
+ * PPR for a particular CPU model and provide useful information about how a
+ * particular PFN is being utilized by the kernel/firmware at the time certain
+ * unexpected events occur, such as RMP faults.
+ */
+static void dump_rmpentry(u64 pfn)
+{
+ u64 pfn_i, pfn_end;
+ struct rmpentry *e;
+ int level;
+
+ e = __snp_lookup_rmpentry(pfn, &level);
+ if (IS_ERR(e)) {
+ pr_err("Failed to read RMP entry for PFN 0x%llx, error %ld\n",
+ pfn, PTR_ERR(e));
+ return;
+ }
+
+ if (e->assigned) {
+ pr_info("PFN 0x%llx, RMP entry: [0x%016llx - 0x%016llx]\n",
+ pfn, e->lo, e->hi);
+ return;
+ }
+
+ /*
+ * If the RMP entry for a particular PFN is not in an assigned state,
+ * then it is sometimes useful to get an idea of whether or not any RMP
+ * entries for other PFNs within the same 2MB region are assigned, since
+ * those too can affect the ability to access a particular PFN in
+ * certain situations, such as when the PFN is being accessed via a 2MB
+ * mapping in the host page table.
+ */
+ pfn_i = ALIGN_DOWN(pfn, PTRS_PER_PMD);
+ pfn_end = pfn_i + PTRS_PER_PMD;
+
+ pr_info("PFN 0x%llx unassigned, dumping non-zero entries in 2M PFN region: [0x%llx - 0x%llx]\n",
+ pfn, pfn_i, pfn_end);
+
+ while (pfn_i < pfn_end) {
+ e = __snp_lookup_rmpentry(pfn_i, &level);
+ if (IS_ERR(e)) {
+ pr_err("Error %ld reading RMP entry for PFN 0x%llx\n",
+ PTR_ERR(e), pfn_i);
+ pfn_i++;
+ continue;
+ }
+
+ if (e->lo || e->hi)
+ pr_info("PFN: 0x%llx, [0x%016llx - 0x%016llx]\n", pfn_i, e->lo, e->hi);
+ pfn_i++;
+ }
+}
+
+void snp_dump_hva_rmpentry(unsigned long hva)
+{
+ unsigned long paddr;
+ unsigned int level;
+ pgd_t *pgd;
+ pte_t *pte;
+
+ pgd = __va(read_cr3_pa());
+ pgd += pgd_index(hva);
+ pte = lookup_address_in_pgd(pgd, hva, &level);
+
+ if (!pte) {
+ pr_err("Can't dump RMP entry for HVA %lx: no PTE/PFN found\n", hva);
+ return;
+ }
+
+ paddr = PFN_PHYS(pte_pfn(*pte)) | (hva & ~page_level_mask(level));
+ dump_rmpentry(PHYS_PFN(paddr));
+}
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