From: Borislav Petkov <bp@alien8.de>
To: Breno Leitao <leitao@debian.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Sean Christopherson <seanjc@google.com>,
Paolo Bonzini <pbonzini@redhat.com>,
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
Date: Wed, 11 Nov 2026 20:57:03 -0800 [thread overview]
Message-ID: <20261112045703.GAavVHH8KA2yyCU7oc@fat_crate.local> (raw)
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)" <bp@alien8.de>
>
> 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
prev parent reply other threads:[~2026-11-12 4:57 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-11 16:06 Breno Leitao
2026-11-12 4:57 ` Borislav Petkov [this message]
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