linux-kernel - Re: [PATCH v6 05/25] x86/fpu/xstate: Remove kernel dynamic xfeatures from kernel default

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Date:   Tue, 31 Oct 2023 19:44:31 +0200
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     Dave Hansen <dave.hansen@...el.com>,
        Yang Weijiang <weijiang.yang@...el.com>, seanjc@...gle.com,
        pbonzini@...hat.com, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     peterz@...radead.org, chao.gao@...el.com,
        rick.p.edgecombe@...el.com, john.allen@....com
Subject: Re: [PATCH v6 05/25] x86/fpu/xstate: Remove kernel dynamic
 xfeatures from kernel default_features

On Thu, 2023-09-14 at 09:22 -0700, Dave Hansen wrote:
> On 9/13/23 23:33, Yang Weijiang wrote:
> > --- a/arch/x86/kernel/fpu/xstate.c
> > +++ b/arch/x86/kernel/fpu/xstate.c
> > @@ -845,6 +845,7 @@ void __init fpu__init_system_xstate(unsigned int legacy_size)
> >  	/* Clean out dynamic features from default */
> >  	fpu_kernel_cfg.default_features = fpu_kernel_cfg.max_features;
> >  	fpu_kernel_cfg.default_features &= ~XFEATURE_MASK_USER_DYNAMIC;
> > +	fpu_kernel_cfg.default_features &= ~fpu_kernel_dynamic_xfeatures;
> 
> I'd much rather that this be a closer analog to XFEATURE_MASK_USER_DYNAMIC.
> 
> Please define a XFEATURE_MASK_KERNEL_DYNAMIC value and use it here.
> Don't use a dynamically generated one.
> 

I also think so.

Best regards,
	Maxim Levitsky