linux-kernel - Re: [PATCH v2 2/6] x86/fpu/xstate: Add CET supervisor mode state support

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Message-ID: <Z8gMK0IMWpLIkgMu@intel.com>
Date: Wed, 5 Mar 2025 16:32:43 +0800
From: Chao Gao <chao.gao@...el.com>
To: Dave Hansen <dave.hansen@...el.com>
CC: <tglx@...utronix.de>, <x86@...nel.org>, <seanjc@...gle.com>,
	<pbonzini@...hat.com>, <linux-kernel@...r.kernel.org>, <kvm@...r.kernel.org>,
	<peterz@...radead.org>, <rick.p.edgecombe@...el.com>, <mlevitsk@...hat.com>,
	<weijiang.yang@...el.com>, <john.allen@....com>
Subject: Re: [PATCH v2 2/6] x86/fpu/xstate: Add CET supervisor mode state
 support

On Tue, Mar 04, 2025 at 02:26:01PM -0800, Dave Hansen wrote:
>On 11/26/24 02:17, Chao Gao wrote:
>...
>> The alternative is to enable it in KVM domain, but KVM maintainers NAKed
>> the solution. The external discussion can be found at [*], it ended up
>> with adding the support in kernel instead of KVM domain.
>So, there's a lot of changelog here, but scant details.

Let me refine the changelog to ensure it's clear and concise and includes all
necessary details.

>
>This patch enables XFEATURE_CET_KERNEL everywhere it's available, right?

Yes

>So, this patch at least wastes the XSAVE buffer space and doesn't
>actually get anything. Right?

Yes