linux-kernel - Re: [PATCH v5 6/7] x86/fpu/xstate: Introduce "guest-only" supervisor xfeature set

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <79e087f7e8e52fbe82ede9169bab587bac42ceb0.camel@intel.com>
Date: Thu, 24 Apr 2025 22:58:59 +0000
From: "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>
To: "Gao, Chao" <chao.gao@...el.com>, "Hansen, Dave" <dave.hansen@...el.com>,
	"seanjc@...gle.com" <seanjc@...gle.com>, "x86@...nel.org" <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"tglx@...utronix.de" <tglx@...utronix.de>, "kvm@...r.kernel.org"
	<kvm@...r.kernel.org>, "pbonzini@...hat.com" <pbonzini@...hat.com>
CC: "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>, "Bae, Chang
 Seok" <chang.seok.bae@...el.com>, "levymitchell0@...il.com"
	<levymitchell0@...il.com>, "samuel.holland@...ive.com"
	<samuel.holland@...ive.com>, "Li, Xin3" <xin3.li@...el.com>, "Yang, Weijiang"
	<weijiang.yang@...el.com>, "mingo@...hat.com" <mingo@...hat.com>,
	"mlevitsk@...hat.com" <mlevitsk@...hat.com>, "john.allen@....com"
	<john.allen@....com>, "vigbalas@....com" <vigbalas@....com>, "hpa@...or.com"
	<hpa@...or.com>, "peterz@...radead.org" <peterz@...radead.org>,
	"aruna.ramakrishna@...cle.com" <aruna.ramakrishna@...cle.com>, "bp@...en8.de"
	<bp@...en8.de>, "Liu, Zhao1" <zhao1.liu@...el.com>, "ubizjak@...il.com"
	<ubizjak@...il.com>
Subject: Re: [PATCH v5 6/7] x86/fpu/xstate: Introduce "guest-only" supervisor
 xfeature set

On Thu, 2025-04-10 at 15:24 +0800, Chao Gao wrote:
> From: Yang Weijiang <weijiang.yang@...el.com>
> 
> In preparation for upcoming CET virtualization support, the CET supervisor
> state will be added as a "guest-only" feature, since it is required only by
> KVM (i.e., guest FPUs). Establish the infrastructure for "guest-only"
> features.
> 
> Define a new XFEATURE_MASK_GUEST_SUPERVISOR mask to specify features that
> are enabled by default in guest FPUs but not in host FPUs. Specifically,
> for any bit in this set, permission is granted and XSAVE space is allocated
> during vCPU creation. Non-guest FPUs cannot enable guest-only features,
> even dynamically, and no XSAVE space will be allocated for them.
> 
> The mask is currently empty, but this will be changed by a subsequent
> patch.
> 
> Note that there is no plan to add "guest-only" user xfeatures, so the user
> default features remain unchanged.
> 
> Co-developed-by: Chao Gao <chao.gao@...el.com>
> Signed-off-by: Chao Gao <chao.gao@...el.com>
> Signed-off-by: Yang Weijiang <weijiang.yang@...el.com>
> ---

Reviewed-by: Rick Edgecombe <rick.p.edgecombe@...el.com>