linux-kernel - Re: [PATCH] KVM: VMX: Fix SPEC

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Message-ID: <176278795912.917009.6888471958480924459.b4-ty@google.com>
Date: Mon, 10 Nov 2025 07:37:31 -0800
From: Sean Christopherson <seanjc@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, kvm@...r.kernel.org, x86@...nel.org, 
	linux-kernel@...r.kernel.org, Uros Bizjak <ubizjak@...il.com>
Cc: Paolo Bonzini <pbonzini@...hat.com>, Josh Poimboeuf <jpoimboe@...nel.org>, 
	Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...nel.org>, Borislav Petkov <bp@...en8.de>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, "H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH] KVM: VMX: Fix SPEC_CTRL handling

On Wed, 20 Aug 2025 11:59:54 +0200, Uros Bizjak wrote:
> SPEC_CTRL is an MSR, i.e. a 64-bit value, but the 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 vmx, with a slightly tweaked shortlog+changelog to call out
that only the guest's value is affected (whereas on SVM both guest and host
values are affected).  Thanks!

[1/1] KVM: VMX: Ensure guest's SPEC_CTRL[63:32] is loaded on VM-Enter
      https://github.com/kvm-x86/linux/commit/32ed0bc2f0f8

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