linux-kernel - Re: [PATCH v5 3/7] x86/fpu/xstate: Differentiate default features for host and guest FPUs

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Message-ID: <aBmCDCZNX+mddOSM@intel.com>
Date: Tue, 6 May 2025 11:29:16 +0800
From: Chao Gao <chao.gao@...el.com>
To: "Chang S. Bae" <chang.seok.bae@...el.com>
CC: <x86@...nel.org>, <linux-kernel@...r.kernel.org>, <kvm@...r.kernel.org>,
	<tglx@...utronix.de>, <dave.hansen@...el.com>, <seanjc@...gle.com>,
	<pbonzini@...hat.com>, <peterz@...radead.org>, <rick.p.edgecombe@...el.com>,
	<weijiang.yang@...el.com>, <john.allen@....com>, <bp@...en8.de>,
	<xin3.li@...el.com>, Ingo Molnar <mingo@...hat.com>, Dave Hansen
	<dave.hansen@...ux.intel.com>, "H. Peter Anvin" <hpa@...or.com>, "Maxim
 Levitsky" <mlevitsk@...hat.com>, Samuel Holland <samuel.holland@...ive.com>,
	Mitchell Levy <levymitchell0@...il.com>, Eric Biggers <ebiggers@...gle.com>,
	Stanislav Spassov <stanspas@...zon.de>, Vignesh Balasubramanian
	<vigbalas@....com>, Aruna Ramakrishna <aruna.ramakrishna@...cle.com>
Subject: Re: [PATCH v5 3/7] x86/fpu/xstate: Differentiate default features
 for host and guest FPUs

On Thu, May 01, 2025 at 07:24:25AM -0700, Chang S. Bae wrote:
>On 4/10/2025 12:24 AM, Chao Gao wrote:
>> 
>> +struct vcpu_fpu_config guest_default_cfg __ro_after_init;
>
>I just noticed that the patch set is missing the initialization of
>guest_default_cfg.size = size (or legacy_size) in the following functions:
>
>   fpu__init_system_xstate_size_legacy()
>   fpu__init_disable_system_xstate()
>
>Without that, it looks buggy when XSAVE is either unavailable or disabled.

Good catch. Will fix them.