linux-kernel - Re: [PATCH AUTOSEL 5.3 28/68] KVM: x86: Expose XSAVEERPTR to the guest

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Message-ID: <20191009214048.irolhz4rwfdiqf2e@linutronix.de>
Date:   Wed, 9 Oct 2019 23:40:48 +0200
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sasha Levin <sashal@...nel.org>, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org, kvm@...r.kernel.org
Subject: Re: [PATCH AUTOSEL 5.3 28/68] KVM: x86: Expose XSAVEERPTR to the
 guest

On 2019-10-09 23:15:07 [+0200], Paolo Bonzini wrote:
> > --- a/arch/x86/kvm/cpuid.c
> > +++ b/arch/x86/kvm/cpuid.c
> > @@ -479,6 +479,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function,
> >  
> >  	/* cpuid 0x80000008.ebx */
> >  	const u32 kvm_cpuid_8000_0008_ebx_x86_features =
> > +		F(XSAVEERPTR) |
> >  		F(WBNOINVD) | F(AMD_IBPB) | F(AMD_IBRS) | F(AMD_SSBD) | F(VIRT_SSBD) |
> >  		F(AMD_SSB_NO) | F(AMD_STIBP) | F(AMD_STIBP_ALWAYS_ON);
> >  
> > 
> 
> Yet another example of a patch that shouldn't be stable material (in
> this case it's fine, but there can certainly be cases where just adding
> a single flag depends on core kernel changes).

Also, taking advantage of this feature requires changes which just
landed in qemu's master branch.

> Paolo

Sebastian