linux-kernel - Re: [kvm-unit-tests] x86/svm: Correctly extract the IP from LBR MSRs

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Message-ID: <176308087438.1726686.11210735704370607564.b4-ty@google.com>
Date: Thu, 13 Nov 2025 16:46:11 -0800
From: Sean Christopherson <seanjc@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, Yosry Ahmed <yosry.ahmed@...ux.dev>
Cc: Paolo Bonzini <pbonzini@...hat.com>, Jim Mattson <jmattson@...gle.com>, kvm@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [kvm-unit-tests] x86/svm: Correctly extract the IP from LBR MSRs

On Thu, 13 Nov 2025 22:46:39 +0000, Yosry Ahmed wrote:
> Currently, only bit 63 is ignored when reading LBR MSRs. However,
> different AMD CPUs use upper bits of the MSR differently. For example,
> some Zen 4 processors document bit 63 in LASTBRACNHFROMIP and bits 63:61
> in LASTBRANCHTOIP to be reserved. On the other hand, some Zen 5
> processors bits 63:57 to be reserved in both MSRs.
> 
> Use the common denominator and always bits 63:57 when reading the LBR
> MSRs, which should be sufficient testing. This fixes the test flaking on
> some AMD processors that set bit 62 in LASTBRANCHTOIP.
> 
> [...]

Applied to kvm-x86 next, thanks!

[1/1] x86/svm: Correctly extract the IP from LBR MSRs
      https://github.com/kvm-x86/kvm-unit-tests/commit/9a7a0e188bd7

--
https://github.com/kvm-x86/kvm-unit-tests/tree/next