linux-kernel - Re: [PATCH] x86/bugs: KVM: Add support for SRSO_MSR

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Message-ID: <f16941c6a33969a373a0a92733631dc578585c93@linux.dev>
Date: Mon, 17 Feb 2025 20:32:26 +0000
From: "Yosry Ahmed" <yosry.ahmed@...ux.dev>
To: "Borislav Petkov" <bp@...en8.de>
Cc: "Sean Christopherson" <seanjc@...gle.com>, "Patrick Bellasi"
 <derkling@...gle.com>, "Paolo Bonzini" <pbonzini@...hat.com>, "Josh
 Poimboeuf" <jpoimboe@...hat.com>, "Pawan Gupta"
 <pawan.kumar.gupta@...ux.intel.com>, x86@...nel.org, kvm@...r.kernel.org,
 linux-kernel@...r.kernel.org, "Patrick Bellasi" <derkling@...bug.net>,
 "Brendan Jackman" <jackmanb@...gle.com>
Subject: Re: [PATCH] x86/bugs: KVM: Add support for SRSO_MSR_FIX

February 17, 2025 at 12:20 PM, "Borislav Petkov" <bp@...en8.de> wrote:
> 
> On Mon, Feb 17, 2025 at 11:56:22AM -0800, Yosry Ahmed wrote:
> 
> > 
> > I meant IBPB + MSR clear before going to userspace, or IBPB + MSR clear
> >  before a context switch.
> > 
> 
> Basically what I said already:
> 
> "Yes, let's keep it simple and do anything more involved *only* if it is
> really necessary."

Right, I agree as I mentioned earlier (assuming the perf hit is 1-2%), just wanted to clarify what I meant.