From: Brijesh Singh <[email protected]>
This information will be useful for debugging things like page faults
due to RMP access violations and RMPUPDATE failures.
Signed-off-by: Brijesh Singh <[email protected]>
Signed-off-by: Ashish Kalra <[email protected]>
[mdr: move helper to standalone patch, rework dump logic to reduce
verbosity]
Signed-off-by: Michael Roth <[email protected]>
---
arch/x86/include/asm/sev.h | 2 +
arch/x86/virt/svm/sev.c | 77 ++++++++++++++++++++++++++++++++++++++
2 files changed, 79 insertions(+)
diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
index 01ce61b283a3..2c53e3de0b71 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 49fdfbf4e518..7c9ced8911e9 100644
--- a/arch/x86/virt/svm/sev.c
+++ b/arch/x86/virt/svm/sev.c
@@ -266,3 +266,80 @@ 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_current, pfn_end;
+ struct rmpentry *e;
+ u64 *e_data;
+ int level;
+
+ e = __snp_lookup_rmpentry(pfn, &level);
+ if (IS_ERR(e)) {
+ pr_info("Failed to read RMP entry for PFN 0x%llx, error %ld\n",
+ pfn, PTR_ERR(e));
+ return;
+ }
+
+ e_data = (u64 *)e;
+ if (e->assigned) {
+ pr_info("RMP entry for PFN 0x%llx: [high=0x%016llx low=0x%016llx]\n",
+ pfn, e_data[1], e_data[0]);
+ 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_current = ALIGN(pfn, PTRS_PER_PMD);
+ pfn_end = pfn_current + PTRS_PER_PMD;
+
+ while (pfn_current < pfn_end) {
+ e = __snp_lookup_rmpentry(pfn_current, &level);
+ if (IS_ERR(e)) {
+ pfn_current++;
+ continue;
+ }
+
+ e_data = (u64 *)e;
+ if (e_data[0] || e_data[1]) {
+ pr_info("No assigned RMP entry for PFN 0x%llx, but the 2MB region contains populated RMP entries, e.g.: PFN 0x%llx: [high=0x%016llx low=0x%016llx]\n",
+ pfn, pfn_current, e_data[1], e_data[0]);
+ return;
+ }
+ pfn_current++;
+ }
+
+ pr_info("No populated RMP entries in the 2MB region containing PFN 0x%llx\n",
+ pfn);
+}
+
+void snp_dump_hva_rmpentry(unsigned long hva)
+{
+ 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_info("Can't dump RMP entry for HVA %lx: no PTE/PFN found\n", hva);
+ return;
+ }
+
+ dump_rmpentry(pte_pfn(*pte));
+}
+EXPORT_SYMBOL_GPL(snp_dump_hva_rmpentry);
--
2.25.1
On Sat, Dec 30, 2023 at 10:19:35AM -0600, Michael Roth wrote:
> +void snp_dump_hva_rmpentry(unsigned long hva)
> +{
> + 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_info("Can't dump RMP entry for HVA %lx: no PTE/PFN found\n", hva);
> + return;
> + }
> +
> + dump_rmpentry(pte_pfn(*pte));
> +}
> +EXPORT_SYMBOL_GPL(snp_dump_hva_rmpentry);
show_fault_oops() - the only caller of this - is builtin code and thus
doesn't need symbol exports. Symbol exports are only for module code.
---
diff --git a/arch/x86/virt/svm/sev.c b/arch/x86/virt/svm/sev.c
index a8cf33b7da71..31154f087fb0 100644
--- a/arch/x86/virt/svm/sev.c
+++ b/arch/x86/virt/svm/sev.c
@@ -339,4 +339,3 @@ void snp_dump_hva_rmpentry(unsigned long hva)
dump_rmpentry(pte_pfn(*pte));
}
-EXPORT_SYMBOL_GPL(snp_dump_hva_rmpentry);
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
On Sat, Dec 30, 2023 at 10:19:35AM -0600, Michael Roth wrote:
> + while (pfn_current < pfn_end) {
> + e = __snp_lookup_rmpentry(pfn_current, &level);
> + if (IS_ERR(e)) {
> + pfn_current++;
> + continue;
> + }
> +
> + e_data = (u64 *)e;
> + if (e_data[0] || e_data[1]) {
> + pr_info("No assigned RMP entry for PFN 0x%llx, but the 2MB region contains populated RMP entries, e.g.: PFN 0x%llx: [high=0x%016llx low=0x%016llx]\n",
> + pfn, pfn_current, e_data[1], e_data[0]);
> + return;
> + }
> + pfn_current++;
> + }
> +
> + pr_info("No populated RMP entries in the 2MB region containing PFN 0x%llx\n",
> + pfn);
> +}
Ok, I went and reworked this, see below.
Yes, I think it is important - at least in the beginning - to dump the
whole 2M PFN region for debugging purposes. If that output starts
becoming too unwieldy and overflowing terminals or log files, we'd
shorten it or put it behind a debug option or so.
Thx.
---
diff --git a/arch/x86/virt/svm/sev.c b/arch/x86/virt/svm/sev.c
index a8cf33b7da71..259a1dd655a7 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;
/*
@@ -272,22 +277,20 @@ EXPORT_SYMBOL_GPL(snp_lookup_rmpentry);
*/
static void dump_rmpentry(u64 pfn)
{
- u64 pfn_current, pfn_end;
+ u64 pfn_i, pfn_end;
struct rmpentry *e;
- u64 *e_data;
int level;
e = __snp_lookup_rmpentry(pfn, &level);
if (IS_ERR(e)) {
- pr_info("Failed to read RMP entry for PFN 0x%llx, error %ld\n",
- pfn, PTR_ERR(e));
+ pr_err("Error %ld reading RMP entry for PFN 0x%llx\n",
+ PTR_ERR(e), pfn);
return;
}
- e_data = (u64 *)e;
if (e->assigned) {
- pr_info("RMP entry for PFN 0x%llx: [high=0x%016llx low=0x%016llx]\n",
- pfn, e_data[1], e_data[0]);
+ pr_info("PFN 0x%llx, RMP entry: [0x%016llx - 0x%016llx]\n",
+ pfn, e->lo, e->hi);
return;
}
@@ -299,27 +302,28 @@ static void dump_rmpentry(u64 pfn)
* certain situations, such as when the PFN is being accessed via a 2MB
* mapping in the host page table.
*/
- pfn_current = ALIGN(pfn, PTRS_PER_PMD);
- pfn_end = pfn_current + PTRS_PER_PMD;
+ pfn_i = ALIGN(pfn, PTRS_PER_PMD);
+ pfn_end = pfn_i + PTRS_PER_PMD;
- while (pfn_current < pfn_end) {
- e = __snp_lookup_rmpentry(pfn_current, &level);
+ pr_info("PFN 0x%llx unassigned, dumping the whole 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)) {
- pfn_current++;
+ pr_err("Error %ld reading RMP entry for PFN 0x%llx\n",
+ PTR_ERR(e), pfn_i);
+ pfn_i++;
continue;
}
- e_data = (u64 *)e;
- if (e_data[0] || e_data[1]) {
- pr_info("No assigned RMP entry for PFN 0x%llx, but the 2MB region contains populated RMP entries, e.g.: PFN 0x%llx: [high=0x%016llx low=0x%016llx]\n",
- pfn, pfn_current, e_data[1], e_data[0]);
- return;
- }
- pfn_current++;
- }
+ if (e->lo || e->hi)
+ pr_info("PFN: 0x%llx, [0x%016llx - 0x%016llx]\n", pfn_i, e->lo, e->hi);
+ else
+ pr_info("PFN: 0x%llx ...\n", pfn_i);
- pr_info("No populated RMP entries in the 2MB region containing PFN 0x%llx\n",
- pfn);
+ pfn_i++;
+ }
}
void snp_dump_hva_rmpentry(unsigned long hva)
@@ -339,4 +343,3 @@ void snp_dump_hva_rmpentry(unsigned long hva)
dump_rmpentry(pte_pfn(*pte));
}
-EXPORT_SYMBOL_GPL(snp_dump_hva_rmpentry);
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
On 12/30/23 10:19, Michael Roth wrote:
> From: Brijesh Singh <[email protected]>
>
> This information will be useful for debugging things like page faults
> due to RMP access violations and RMPUPDATE failures.
>
> Signed-off-by: Brijesh Singh <[email protected]>
> Signed-off-by: Ashish Kalra <[email protected]>
> [mdr: move helper to standalone patch, rework dump logic to reduce
> verbosity]
> Signed-off-by: Michael Roth <[email protected]>
> ---
> arch/x86/include/asm/sev.h | 2 +
> arch/x86/virt/svm/sev.c | 77 ++++++++++++++++++++++++++++++++++++++
> 2 files changed, 79 insertions(+)
>
> diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
> index 01ce61b283a3..2c53e3de0b71 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 49fdfbf4e518..7c9ced8911e9 100644
> --- a/arch/x86/virt/svm/sev.c
> +++ b/arch/x86/virt/svm/sev.c
> @@ -266,3 +266,80 @@ 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_current, pfn_end;
> + struct rmpentry *e;
> + u64 *e_data;
> + int level;
> +
> + e = __snp_lookup_rmpentry(pfn, &level);
> + if (IS_ERR(e)) {
> + pr_info("Failed to read RMP entry for PFN 0x%llx, error %ld\n",
> + pfn, PTR_ERR(e));
> + return;
> + }
> +
> + e_data = (u64 *)e;
> + if (e->assigned) {
> + pr_info("RMP entry for PFN 0x%llx: [high=0x%016llx low=0x%016llx]\n",
> + pfn, e_data[1], e_data[0]);
> + 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_current = ALIGN(pfn, PTRS_PER_PMD);
> + pfn_end = pfn_current + PTRS_PER_PMD;
> +
> + while (pfn_current < pfn_end) {
> + e = __snp_lookup_rmpentry(pfn_current, &level);
> + if (IS_ERR(e)) {
> + pfn_current++;
> + continue;
> + }
> +
> + e_data = (u64 *)e;
> + if (e_data[0] || e_data[1]) {
> + pr_info("No assigned RMP entry for PFN 0x%llx, but the 2MB region contains populated RMP entries, e.g.: PFN 0x%llx: [high=0x%016llx low=0x%016llx]\n",
> + pfn, pfn_current, e_data[1], e_data[0]);
> + return;
> + }
> + pfn_current++;
> + }
> +
> + pr_info("No populated RMP entries in the 2MB region containing PFN 0x%llx\n",
> + pfn);
> +}
> +
> +void snp_dump_hva_rmpentry(unsigned long hva)
> +{
> + 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_info("Can't dump RMP entry for HVA %lx: no PTE/PFN found\n", hva);
> + return;
> + }
> +
> + dump_rmpentry(pte_pfn(*pte));
Already worked with Mike offline when I was running into issues using this
function. Net of that conversation is that the PFN needs to be adjusted
using the address offset if the PTE level indicates a huge page.
Additionally the loop in dump_rmpentry() needs to use ALIGN_DOWN() in
order to get the PFN of the starting 2MB area.
Thanks,
Tom
> +}
> +EXPORT_SYMBOL_GPL(snp_dump_hva_rmpentry);
On 1/10/24 09:27, Borislav Petkov wrote:
> On Wed, Jan 10, 2024 at 09:20:44AM -0600, Tom Lendacky wrote:
>> How about saying "... dumping all non-zero entries in the whole ..."
>
> I'm trying not to have long stories in printk statements :)
Well it only adds "non-zero"
>
>> and then removing the print below that prints the PFN and "..."
>
> Why remove the print? You want to print every non-null RMP entry in the
> 2M range, no?
I'm only suggesting getting rid of the else that prints "..." when the
entry is all zeroes. Printing the non-zero entries would still occur.
Thanks,
Tom
>
> And the "..." says that it is a null entry.
>
On Wed Jan 10, 2024 at 11:59 AM EET, Borislav Petkov wrote:
> On Sat, Dec 30, 2023 at 10:19:35AM -0600, Michael Roth wrote:
> > +void snp_dump_hva_rmpentry(unsigned long hva)
> > +{
> > + 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_info("Can't dump RMP entry for HVA %lx: no PTE/PFN found\n", hva);
~~~~~~~
is this correct log level?
BR, Jarkko
On Wed, Jan 10, 2024 at 09:51:04AM -0600, Tom Lendacky wrote:
> I'm only suggesting getting rid of the else that prints "..." when the entry
> is all zeroes. Printing the non-zero entries would still occur.
Sure, one should be able to to infer that the missing entries are null.
:-)
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette