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Mon, 2 Nov 2026 21:43:46 +0000 (UTC) Date: Mon, 2 Nov 2026 13:43:43 -0800 From: Borislav Petkov To: Tom Lendacky Cc: "Kalra, Ashish" , K Prateek Nayak , tglx@kernel.org, mingo@redhat.com, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, seanjc@google.com, peterz@infradead.org, herbert@gondor.apana.org.au, davem@davemloft.net, ardb@kernel.org, pbonzini@redhat.com, aik@amd.com, Michael.Roth@amd.com, Tycho.Andersen@amd.com, Nathan.Fontenot@amd.com, ackerleytng@google.com, jackyli@google.com, pgonda@google.com, rientjes@google.com, jacobhxu@google.com, xin@zytor.com, pawan.kumar.gupta@linux.intel.com, babu.moger@amd.com, dyoung@redhat.com, nikunj@amd.com, darwi@linutronix.de, linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org, kvm@vger.kernel.org, linux-coco@lists.linux.dev Subject: Re: [PATCH v4 1/2] x86/sev: Clear RMPOPT when segmented RMP is disabled by firmware Message-ID: <20261102214343.GFaukED8ep3EMmQxfx@fat_crate.local> References: <56da047d63b22f03a7e709fc172a5543da894d67.1793216372.git.ashish.kalra@amd.com> <20261102052841.GBaugfibOXxGorZKgq@fat_crate.local> <69ed0d93-f96d-4baa-a587-fade5a0a3262@amd.com> <414b2fc2-a55a-4b2d-ac70-4def101c4aee@amd.com> <20261102144805.GCauiipTaEXcg6Lr59@fat_crate.local> <20261102193116.GDaujlBJc3XjG3xzLj@fat_crate.local> <9ebcb83a-1c0e-423a-8730-eff6b710634b@amd.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <9ebcb83a-1c0e-423a-8730-eff6b710634b@amd.com> On Mon, Nov 02, 2026 at 03:25:52PM -0600, Tom Lendacky wrote: > The current code clears X86_FEATURE_RMPOPT when > probe_segmented_rmptable_info() fails. The above code doesn't. See the hunk in cpuid-deps.c > But since SNP will be disabled on failure of snp_probe_rmptable_info(), > I guess it doesn't matter. In which case you can eliminate the goto by > doing: > > if (cpu_feature_enabled(X86_FEATURE_SEGMENTED_RMP)) { > rdmsrq(MSR_AMD64_RMP_CFG, rmp_cfg); > if (rmp_cfg & MSR_AMD64_SEG_RMP_ENABLED) > return probe_segmented_rmptable_info(); > } > > setup_clear_cpu_cap(X86_FEATURE_RMPOPT); > return probe_contiguous_rmptable_info(); > > Which looks pretty clean. Yap. > > diff --git a/arch/x86/kernel/cpu/cpuid-deps.c b/arch/x86/kernel/cpu/cpuid-deps.c > > index 99801e844b30..acbcec394ef1 100644 > > --- a/arch/x86/kernel/cpu/cpuid-deps.c > > +++ b/arch/x86/kernel/cpu/cpuid-deps.c > > @@ -93,6 +93,7 @@ static const struct cpuid_dep cpuid_deps[] = { > > { X86_FEATURE_SPEC_CTRL_SSBD, X86_FEATURE_SPEC_CTRL }, > > { X86_FEATURE_LASS, X86_FEATURE_SMAP }, > > { X86_FEATURE_INVLPGB, X86_FEATURE_PCID }, > > + { X86_FEATURE_RMPOPT, X86_FEATURE_SEV_SNP }, This hunk. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette