From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 0207110FD for ; Wed, 22 Jun 2022 14:33:16 +0000 (UTC) Received: from jpiotrowski-Surface-Book-3 (ip-037-201-214-204.um10.pools.vodafone-ip.de [37.201.214.204]) by linux.microsoft.com (Postfix) with ESMTPSA id F368F20C5A72; Wed, 22 Jun 2022 07:33:09 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com F368F20C5A72 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1655908396; bh=ALGB76keBASr4hY7hNxpqQX9PoomTfBUh9uHAgUzoZ0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=TQuQbeqWbRyJqyFmVhgUuEJoBS5K/iwNUxkPx+opP5jeWVfpzXQI4KzNOllCIS2zh mU8FnTjBX9ClQRIxHfXEKNV839Uq5DWJzew4nztCg0vmsZJ+56JSnTEpM4fqmceN0D tXbZpMynZVvEgvrwBOTlSQAdtEXVMixKZZIm5rYI= Date: Wed, 22 Jun 2022 16:33:04 +0200 From: Jeremi Piotrowski To: Ashish Kalra Cc: x86@kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-coco@lists.linux.dev, linux-mm@kvack.org, linux-crypto@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, jroedel@suse.de, thomas.lendacky@amd.com, hpa@zytor.com, ardb@kernel.org, pbonzini@redhat.com, seanjc@google.com, vkuznets@redhat.com, jmattson@google.com, luto@kernel.org, dave.hansen@linux.intel.com, slp@redhat.com, pgonda@google.com, peterz@infradead.org, srinivas.pandruvada@linux.intel.com, rientjes@google.com, dovmurik@linux.ibm.com, tobin@ibm.com, bp@alien8.de, michael.roth@amd.com, vbabka@suse.cz, kirill@shutemov.name, ak@linux.intel.com, tony.luck@intel.com, marcorr@google.com, sathyanarayanan.kuppuswamy@linux.intel.com, alpergun@google.com, dgilbert@redhat.com, jarkko@kernel.org Subject: Re: [PATCH Part2 v6 10/49] x86/fault: Add support to dump RMP entry on fault Message-ID: References: Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Mon, Jun 20, 2022 at 11:03:58PM +0000, Ashish Kalra wrote: > 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) { __snp_lookup_rmpentry may return -errno so this should be: if (e != 1) > + 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) if (e != 1) > + 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 */ > -- > 2.25.1 >