linux-kernel - Re: [PATCH v6 5/7] x86/fpu: Initialize guest fpstate and FPU pseudo container from guest defaults

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Message-ID: <15c80733-5cd8-4d9a-9fda-0d0ec305ac6b@intel.com>
Date: Wed, 7 May 2025 11:04:05 -0700
From: Dave Hansen <dave.hansen@...el.com>
To: Sean Christopherson <seanjc@...gle.com>, Chao Gao <chao.gao@...el.com>
Cc: x86@...nel.org, linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
 tglx@...utronix.de, pbonzini@...hat.com, peterz@...radead.org,
 rick.p.edgecombe@...el.com, weijiang.yang@...el.com, john.allen@....com,
 bp@...en8.de, chang.seok.bae@...el.com, xin3.li@...el.com,
 Ingo Molnar <mingo@...hat.com>, Dave Hansen <dave.hansen@...ux.intel.com>,
 "H. Peter Anvin" <hpa@...or.com>, Oleg Nesterov <oleg@...hat.com>,
 Eric Biggers <ebiggers@...gle.com>, Stanislav Spassov <stanspas@...zon.de>,
 Kees Cook <kees@...nel.org>
Subject: Re: [PATCH v6 5/7] x86/fpu: Initialize guest fpstate and FPU pseudo
 container from guest defaults

On 5/7/25 11:01, Sean Christopherson wrote:
> And then a follow-up patch (or same patch?) to do this?
> 
> 	if (fpstate->is_guest) {
> 		fpstate->size           = guest_default_cfg.size;
> 		fpstate->xfeatures      = guest_default_cfg.features;
> 		fpstate->xfd		= 0;
> 	} else {
> 		fpstate->size           = fpu_kernel_cfg.default_size;
> 		fpstate->xfeatures      = fpu_kernel_cfg.default_features;
> 		fpstate->xfd		= init_fpstate.xfd;
> 	}

That looks nice because it clearly highlights how guests and bare-metal
fpstates are different. I like it too.