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Wed, 15 Nov 2023 16:09:01 +0000 (UTC) Date: Wed, 15 Nov 2023 17:08:52 +0100 From: Borislav Petkov To: Michael Roth Cc: kvm@vger.kernel.org, linux-coco@lists.linux.dev, linux-mm@kvack.org, linux-crypto@vger.kernel.org, x86@kernel.org, linux-kernel@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, 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, jarkko@kernel.org, ashish.kalra@amd.com, nikunj.dadhania@amd.com, pankaj.gupta@amd.com, liam.merwick@oracle.com, zhi.a.wang@intel.com, Brijesh Singh Subject: Re: [PATCH v10 08/50] x86/fault: Add helper for dumping RMP entries Message-ID: <20231115160852.GDZVTtFHB0+HpVZnpG@fat_crate.local> References: <20231016132819.1002933-1-michael.roth@amd.com> <20231016132819.1002933-9-michael.roth@amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20231016132819.1002933-9-michael.roth@amd.com> X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: C2718100021 X-Stat-Signature: h5ukonewwpss8rgb4k7a73qk5ntpi3a8 X-HE-Tag: 1700064589-958769 X-HE-Meta: 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 C86BzxZz S+8TvFb49UxjwdmnpEU8F+3+Nvw9ZG4Hy0D7AvFddRLGpesn9uAioGt4vELP5Uur2arM6TilazM+d6ygR8aUGOXdp5PmOh9zY5oGQZZgPK8Da6jjzox/2CCMWVbmpslAKjondoNoRWFJdNkbV94BpHYo/pbWe2q70UJVTYraUZ0eb//MyXEfrdRLTpyWnPwuoQdmaE02JQps87g0= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Oct 16, 2023 at 08:27:37AM -0500, Michael Roth wrote: > +/* > + * 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 sev_dump_rmpentry(u64 dumped_pfn) Just "dump_rmentry" s/dumped_pfn/pfn/g > + struct rmpentry e; > + u64 pfn, pfn_end; > + int level, ret; > + u64 *e_data; > + > + ret = __snp_lookup_rmpentry(dumped_pfn, &e, &level); > + if (ret) { > + pr_info("Failed to read RMP entry for PFN 0x%llx, error %d\n", > + dumped_pfn, ret); > + return; > + } > + > + e_data = (u64 *)&e; > + if (e.assigned) { > + pr_info("RMP entry for PFN 0x%llx: [high=0x%016llx low=0x%016llx]\n", > + dumped_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 = ALIGN(dumped_pfn, PTRS_PER_PMD); > + pfn_end = pfn + PTRS_PER_PMD; > + > + while (pfn < pfn_end) { > + ret = __snp_lookup_rmpentry(pfn, &e, &level); > + if (ret) { > + pr_info_ratelimited("Failed to read RMP entry for PFN 0x%llx\n", pfn); Why ratelmited? No need to print anything if you fail to read it - simply dump the range [pfn, pfn_end], _data[0], e_data[1] exactly *once* before the loop and inside the loop dump only the ones you can lookup... > + pfn++; > + continue; > + } > + > + 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", > + dumped_pfn, pfn, e_data[1], e_data[0]); > + return; > + } > + pfn++; > + } > + > + pr_info("No populated RMP entries in the 2MB region containing PFN 0x%llx\n", > + dumped_pfn); ... and then you don't need this one either. > +} > + > +void sev_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 this is using the current CR3, why aren't you simply using lookup_address() here without the need to read pgd? > + > + if (pte) { if (!pte) Doh. > + pr_info("Can't dump RMP entry for HVA %lx: no PTE/PFN found\n", hva); > + return; > + } > + > + sev_dump_rmpentry(pte_pfn(*pte)); > +} > +EXPORT_SYMBOL_GPL(sev_dump_hva_rmpentry); Who's going to use this, kvm? -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette