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 4EA7610FD for ; Wed, 22 Jun 2022 14:42:57 +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 02ADF20C636D; Wed, 22 Jun 2022 07:42:49 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 02ADF20C636D DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1655908976; bh=3p9ZjAM7sex59sizUKu6QYDFUGr8EeBgiFOquCcUwkM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=NrPWRQQBC2o9oajSPE53nnlzATXfEgf2dHagcUN5LS60Ha4Ezvaot2T5Wvu8C10g0 CHJNf3C+lOyYd+OCx34K+ndvZuVfuqQtRBHXe7I3O+OzymGWnyTO5o3t6LiWs6voaT SSnTy1rlZf9JbY4YZH3R4tktCGmleekxZdzRoF5o= Date: Wed, 22 Jun 2022 16:42:45 +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 Wed, Jun 22, 2022 at 04:33:04PM +0200, Jeremi Piotrowski wrote: > 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) Sorry, actually it should be: if (IS_ERR_OR_NULL(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) > > if (e != 1) > and this too: if (IS_ERR_OR_NULL(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 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 > >