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Peter Anvin" , Sean Christopherson , Paolo Bonzini , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, vlad.wing@gmail.com, security@kernel.org, kernel-team@meta.com Subject: Re: [PATCH 6.18.y] x86/cpufeatures: Make X86_FEATURE leaf 17 Linux-specific Message-ID: <20261112045703.GAavVHH8KA2yyCU7oc@fat_crate.local> References: <20261111-stabe_srso-v1-1-45512320ba5e@debian.org> 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: <20261111-stabe_srso-v1-1-45512320ba5e@debian.org> On Wed, Nov 11, 2026 at 08:06:21AM -0800, Breno Leitao wrote: > From: "Borislav Petkov (AMD)" > > commit ddde4abaa0ecc8395e0fcfa3e92f65d481890cc8 upstream. > > That cpuinfo_x86.x86_capability[] element was supposed to mirror CPUID flags > from CPUID_0x80000007_EBX but that leaf has still to this day only three bits > defined in it. So move those bits to scattered.c and free the capability > element for synthetic flags. > > No functional changes. > > [ leitao: Required on 6.18.y: the 6.18.61 backport of ae1d2082d93b > ("x86/bugs: Adapt SRSO mitigation to Zen6") put BTB_CTX_ISOLATION in > word 17, which here still mirrors CPUID 0x80000007 EBX. The flag is > then falsely set on Zen3-5, and Zen5 silently loses its guest->host > SRSO mitigation. ] Good catch, dang. That's nasty one. Thanks! -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette