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AJvYcCVYK9MIUPYdyBqlaj7Xv2pFGlaNDJ5tsKyArKMg3GO8nYPXHv/nrvUu6khCFyxnO4oNskc=@vger.kernel.org X-Gm-Message-State: AOJu0YyiL+5140sUYAnuEWvQZwORakafprsJK04gMcLuC9ZuOpvFWbPi s9FB86Qiz09seTcE/9Fe/Vbnx4ge3rezoghaNyVeOZgrVp39pKLCFOQAdVQ2c/IR/Td3IA5K66w Z/cs+sg== X-Google-Smtp-Source: AGHT+IG2OX9by+gRk6KXY2gIknfbeeJ6jUNBwEq6BQRV737htpu9tNGRhCQVKub87SnNL/+3BP22reUnOkk= X-Received: from pgct20.prod.google.com ([2002:a05:6a02:5294:b0:bbf:9fd6:ee92]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a20:748e:b0:253:1e04:4e8 with SMTP id adf61e73a8af0-3590c00a2dcmr737871637.56.1762898621804; Tue, 11 Nov 2025 14:03:41 -0800 (PST) Date: Tue, 11 Nov 2025 14:03:40 -0800 In-Reply-To: <20251107190534.GTaQ5C_l_UsZmQR1ph@fat_crate.local> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20251031003040.3491385-1-seanjc@google.com> <20251031003040.3491385-2-seanjc@google.com> <20251103181840.kx3egw5fwgzpksu4@desk> <20251107190534.GTaQ5C_l_UsZmQR1ph@fat_crate.local> Message-ID: Subject: Re: [PATCH v4 1/8] x86/bugs: Use VM_CLEAR_CPU_BUFFERS in VMX as well From: Sean Christopherson To: Borislav Petkov Cc: Pawan Gupta , Paolo Bonzini , Thomas Gleixner , Peter Zijlstra , Josh Poimboeuf , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Brendan Jackman Content-Type: text/plain; charset="us-ascii" On Fri, Nov 07, 2025, Borislav Petkov wrote: > On Mon, Nov 03, 2025 at 10:18:40AM -0800, Pawan Gupta wrote: > > diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h > > index 08ed5a2e46a5..2be9be782013 100644 > > --- a/arch/x86/include/asm/nospec-branch.h > > +++ b/arch/x86/include/asm/nospec-branch.h > > @@ -321,9 +321,11 @@ > > #endif > > .endm > > > > +/* Primarily used in exit-to-userspace path */ > > What does "primarily" mean here? > > $ git grep -w CLEAR_CPU_BUFFERS > > says *only* the kernel->user vector. How about: /* If necessary, emit VERW on exit-to-userspace to clear CPU buffers. */ #define CLEAR_CPU_BUFFERS \ ALTERNATIVE "", __CLEAR_CPU_BUFFERS, X86_FEATURE_CLEAR_CPU_BUF > > > #define CLEAR_CPU_BUFFERS \ > > __CLEAR_CPU_BUFFERS X86_FEATURE_CLEAR_CPU_BUF > > > > +/* For use in KVM */ > > That's why the "VM_" prefix is there. Ya, and this goes away (moved into SVM) by the end of the series.