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([2001:b07:6468:f312:9af8:e5f5:7516:fa89]) by smtp.googlemail.com with ESMTPSA id x15-20020adfdd8f000000b002365921c9aesm13026740wrl.77.2022.11.09.02.35.42 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 09 Nov 2022 02:35:43 -0800 (PST) Message-ID: <1fc523b0-da9c-64a0-7459-e8cf9fe3b819@redhat.com> Date: Wed, 9 Nov 2022 11:35:41 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.4.0 Subject: Re: [PATCH v2 2/8] KVM: SVM: replace regs argument of __svm_vcpu_run with vcpu_svm Content-Language: en-US To: Sean Christopherson Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, nathan@kernel.org, thomas.lendacky@amd.com, andrew.cooper3@citrix.com, peterz@infradead.org, jmattson@google.com, stable@vger.kernel.org References: <20221108151532.1377783-1-pbonzini@redhat.com> <20221108151532.1377783-3-pbonzini@redhat.com> From: Paolo Bonzini In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/8/22 21:54, Sean Christopherson wrote: > On Tue, Nov 08, 2022, Paolo Bonzini wrote: >> Since registers are reachable through vcpu_svm, and we will >> need to access more fields of that struct, pass it instead >> of the regs[] array. >> >> No functional change intended. >> >> Cc: stable@vger.kernel.org >> Fixes: f14eec0a3203 ("KVM: SVM: move more vmentry code to assembly") > > I don't think a Fixes: tag for a pure nop patch is fair to the original commit. That's for the sake of correct tracking in stable@, still it's not the right commit to point at: - f14eec0a3203 did not move the RSB stuffing before the GSBASE restore, the code before was: vmexit_fill_RSB(); #ifdef CONFIG_X86_64 wrmsrl(MSR_GS_BASE, svm->host.gs_base); #else - anyway it wasn't really buggy at the time: it's only in -next that FILL_RETURN_BUFFER uses percpu data, because alternatives take care of the X86_FEATURE_* checks The real reason to do all this is to access the percpu host spec_ctrl, which in turn is needed for retbleed. I'll point the Fixes tag to a149180fbcf3 ("x86: Add magic AMD return-thunk") instead, again just for the sake of tracking releases that need the change to full fix retbleed. Paolo