linux-kernel - Re: [PATCH v2] KVM: SVM: Ensure SPEC_CTRL[63:32] is context switched between guest and host

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Message-ID: <176254226343.805329.8193068148325939353.b4-ty@google.com>
Date: Mon, 10 Nov 2025 07:37:25 -0800
From: Sean Christopherson <seanjc@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Uros Bizjak <ubizjak@...il.com>
Subject: Re: [PATCH v2] KVM: SVM: Ensure SPEC_CTRL[63:32] is context switched
 between guest and host

On Thu, 06 Nov 2025 11:12:30 -0800, Sean Christopherson wrote:
> SPEC_CTRL is an MSR, i.e. a 64-bit value, but the VMRUN assembly code
> assumes bits 63:32 are always zero.  The bug is _currently_ benign because
> neither KVM nor the kernel support setting any of bits 63:32, but it's
> still a bug that needs to be fixed.

Applied to kvm-x86 svm, with the comment fixups.

[1/1] KVM: SVM: Ensure SPEC_CTRL[63:32] is context switched between guest and host
      https://github.com/kvm-x86/linux/commit/c331b400e291

--
https://github.com/kvm-x86/linux/tree/next