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

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Message-ID: <3c4cc319-feac-461d-a846-7275b0ebca4b@intel.com>
Date: Thu, 1 May 2025 07:24:25 -0700
From: "Chang S. Bae" <chang.seok.bae@...el.com>
To: Chao Gao <chao.gao@...el.com>, <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>
CC: <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 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.

Thanks,
Chang