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AJvYcCVtY0K5GLERC3YKNayLjNinGGoSZegN0PgZMvsrPisjhA3z0YrVMO0DCwwGrkJZDVqLLevBfm+duMuOmESU2qKJZ1cUZQW0eFjlHNbX X-Gm-Message-State: AOJu0YymqPQgE8mqcAFMg++NCWh6d1K0EAOC5e4lL1S3oFU1eP/p2G5I IakiTsj517qVRQUpz6cHRy1DSB24c8oZK5PstSRF8H+cWnLESv0fqFUEOgFJwiY9bH8zTmEHYTB S9g== X-Google-Smtp-Source: AGHT+IE/lQuPOTvDxWjzkM/iusdROrnl0/N7wrOKUBofNs3qRmYLDyhVrHon2c6cmTGKid45nIAheN1qXvg= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a05:6902:150a:b0:dd9:2a64:e98a with SMTP id q10-20020a056902150a00b00dd92a64e98amr425840ybu.9.1714607274831; Wed, 01 May 2024 16:47:54 -0700 (PDT) Date: Wed, 1 May 2024 16:47:53 -0700 In-Reply-To: <20240226213244.18441-10-john.allen@amd.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240226213244.18441-1-john.allen@amd.com> <20240226213244.18441-10-john.allen@amd.com> Message-ID: Subject: Re: [PATCH v2 9/9] KVM: SVM: Add CET features to supported_xss From: Sean Christopherson To: John Allen Cc: kvm@vger.kernel.org, weijiang.yang@intel.com, rick.p.edgecombe@intel.com, thomas.lendacky@amd.com, bp@alien8.de, pbonzini@redhat.com, mlevitsk@redhat.com, linux-kernel@vger.kernel.org, x86@kernel.org Content-Type: text/plain; charset="us-ascii" On Mon, Feb 26, 2024, John Allen wrote: > If the CPU supports CET, add CET XSAVES feature bits to the > supported_xss mask. > > Signed-off-by: John Allen > --- > arch/x86/kvm/svm/svm.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c > index 1181f017c173..d97d82ebec4a 100644 > --- a/arch/x86/kvm/svm/svm.c > +++ b/arch/x86/kvm/svm/svm.c > @@ -5177,6 +5177,10 @@ static __init void svm_set_cpu_caps(void) > boot_cpu_has(X86_FEATURE_AMD_SSBD)) > kvm_cpu_cap_set(X86_FEATURE_VIRT_SSBD); > > + if (kvm_cpu_cap_has(X86_FEATURE_SHSTK)) > + kvm_caps.supported_xss |= XFEATURE_MASK_CET_USER | > + XFEATURE_MASK_CET_KERNEL; Based on Weijiang's series, I believe this is unnecessary. Common x86 code will both set supported_xss, and clear bits if their associated features are unsupported. I also asked Weijiang to modify the "advertise to userspace" patch to explicitly clear SHSTK and IBT in svm_set_cpu_caps()[*], so if the stars align as I think they will, this patch should simply need to delete the kvm_cpu_cap_clear(X86_FEATURE_SHSTK); that will be added by the VMX series. [*] https://lore.kernel.org/all/ZjLRnisdUgeYgg8i@google.com