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Tue, 14 Nov 2023 14:24:48 +0000 (UTC) Date: Tue, 14 Nov 2023 15:24:42 +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 07/50] x86/sev: Add RMP entry lookup helpers Message-ID: <20231114142442.GCZVODKh03BoMFdlmj@fat_crate.local> References: <20231016132819.1002933-1-michael.roth@amd.com> <20231016132819.1002933-8-michael.roth@amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20231016132819.1002933-8-michael.roth@amd.com> X-Rspamd-Queue-Id: 966501C001D X-Rspam-User: X-Rspamd-Server: rspam04 X-Stat-Signature: o631d5ucwxt6mbonejthw49j4wdw7oaf X-HE-Tag: 1699971936-677259 X-HE-Meta: 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 nvbnnt4M mIa/FFBvEo/AzV/rZEm8h+IJhceaaYThu0az8BPt9FLdiDN8ObR0wJ0UYQnpbVtHcVsfMFK3UC+wvar+0mwqw3p/soa1Merj5QJrK9v68QoZpU93x37iYw+APAl6n1PYs9y9R/uw/g8VZa6Jcy1tEVvJHM5qpBh4e+FTKkG6934mmnNrIAW18dsdT3QW/JXW7Dkjs3rKpMArt4k3r2GOLg2/s8uZWrDll0OfA 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 08:27:36AM -0500, Michael Roth wrote: > From: Brijesh Singh > > The snp_lookup_page_in_rmptable() can be used by the host to read the RMP $ git grep snp_lookup_page_in_rmptable $ Stale commit message. And not very telling. Please rewrite. > entry for a given page. The RMP entry format is documented in AMD PPR, see > https://bugzilla.kernel.org/attachment.cgi?id=296015. <--- Brijesh's SOB comes first here if he's the primary author. > Co-developed-by: Ashish Kalra > Signed-off-by: Ashish Kalra > Signed-off-by: Brijesh Singh > [mdr: separate 'assigned' indicator from return code] > Signed-off-by: Michael Roth > --- > arch/x86/include/asm/sev-common.h | 4 +++ > arch/x86/include/asm/sev-host.h | 22 +++++++++++++ > arch/x86/virt/svm/sev.c | 53 +++++++++++++++++++++++++++++++ > 3 files changed, 79 insertions(+) > create mode 100644 arch/x86/include/asm/sev-host.h > > diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h > index b463fcbd4b90..1e6fb93d8ab0 100644 > --- a/arch/x86/include/asm/sev-common.h > +++ b/arch/x86/include/asm/sev-common.h > @@ -173,4 +173,8 @@ struct snp_psc_desc { > #define GHCB_ERR_INVALID_INPUT 5 > #define GHCB_ERR_INVALID_EVENT 6 > > +/* RMP page size */ > +#define RMP_PG_SIZE_4K 0 RMP_PG_LEVEL_4K just like the generic ones. > +#define RMP_TO_X86_PG_LEVEL(level) (((level) == RMP_PG_SIZE_4K) ? PG_LEVEL_4K : PG_LEVEL_2M) What else is there besides X86 PG level? IOW, RMP_TO_PG_LEVEL simply. > + > #endif > diff --git a/arch/x86/include/asm/sev-host.h b/arch/x86/include/asm/sev-host.h Nah, we don't need a third sev header: arch/x86/include/asm/sev-common.h arch/x86/include/asm/sev.h arch/x86/include/asm/sev-host.h Put it in sev.h pls. sev-common.h should be merged into sev.h too unless there's a compelling reason not to which I don't see atm. > new file mode 100644 > index 000000000000..4c487ce8457f > --- /dev/null > +++ b/arch/x86/include/asm/sev-host.h ... > diff --git a/arch/x86/virt/svm/sev.c b/arch/x86/virt/svm/sev.c > index 8b9ed72489e4..7d3802605376 100644 > --- a/arch/x86/virt/svm/sev.c > +++ b/arch/x86/virt/svm/sev.c > @@ -53,6 +53,9 @@ struct rmpentry { > */ > #define RMPTABLE_CPU_BOOKKEEPING_SZ 0x4000 > > +/* Mask to apply to a PFN to get the first PFN of a 2MB page */ > +#define PFN_PMD_MASK (~((1ULL << (PMD_SHIFT - PAGE_SHIFT)) - 1)) GENMASK_ULL > static struct rmpentry *rmptable_start __ro_after_init; > static u64 rmptable_max_pfn __ro_after_init; > > @@ -237,3 +240,53 @@ static int __init snp_rmptable_init(void) > * the page(s) used for DMA are hypervisor owned. > */ > fs_initcall(snp_rmptable_init); > + > +static int rmptable_entry(u64 pfn, struct rmpentry *entry) The signature of this one should be: static struct rmpentry *get_rmp_entry(u64 pfn) and the callers should use the IS_ERR* macros to check whether it returns a valid pointer or a negative value for error. Ditto for the other two functions here. > + if (WARN_ON_ONCE(pfn > rmptable_max_pfn)) > + return -EFAULT; > + > + *entry = rmptable_start[pfn]; This wants to be called rmptable[] then. > + > + return 0; > +} > + > +static int __snp_lookup_rmpentry(u64 pfn, struct rmpentry *entry, int *level) > +{ > + struct rmpentry large_entry; > + int ret; > + > + if (!cpu_feature_enabled(X86_FEATURE_SEV_SNP)) > + return -ENXIO; ENODEV or so. > + > + ret = rmptable_entry(pfn, entry); > + if (ret) > + return ret; > + > + /* > + * Find the authoritative RMP entry for a PFN. This can be either a 4K > + * RMP entry or a special large RMP entry that is authoritative for a > + * whole 2M area. > + */ > + ret = rmptable_entry(pfn & PFN_PMD_MASK, &large_entry); > + if (ret) > + return ret; > + > + *level = RMP_TO_X86_PG_LEVEL(large_entry.pagesize); > + > + return 0; > +} > + > +int snp_lookup_rmpentry(u64 pfn, bool *assigned, int *level) > +{ > + struct rmpentry e; > + int ret; > + > + ret = __snp_lookup_rmpentry(pfn, &e, level); > + if (ret) > + return ret; > + > + *assigned = !!e.assigned; > + return 0; > +} > +EXPORT_SYMBOL_GPL(snp_lookup_rmpentry); > -- Thx. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette