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

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Message-ID: <20250218153414.GMZ7Sodh_eQXqTNE2x@fat_crate.local>
Date: Tue, 18 Feb 2025 16:34:14 +0100
From: Borislav Petkov <bp@...en8.de>
To: Patrick Bellasi <derkling@...gle.com>
Cc: Sean Christopherson <seanjc@...gle.com>,
	Yosry Ahmed <yosry.ahmed@...ux.dev>,
	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>,
	David Kaplan <David.Kaplan@....com>
Subject: Re: [PATCH final?] x86/bugs: KVM: Add support for SRSO_MSR_FIX

On Tue, Feb 18, 2025 at 02:42:57PM +0000, Patrick Bellasi wrote:
> Maybe a small improvement we could add on top is to have a separate and
> dedicated cmdline option?
> 
> Indeed, with `X86_FEATURE_SRSO_USER_KERNEL_NO` we are not effectively using an
> IBPB on VM-Exit anymore. Something like the diff down below?

Except that I don't see the point of this yet one more cmdline option. Our
mitigations options space is a nightmare. Why do we want to add another one?

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette