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

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Message-ID: <7119916d-462e-8ba8-300c-c165d9df045a@redhat.com>
Date:   Thu, 10 Oct 2019 00:50:09 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>
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 09/10/19 23:40, Sebastian Andrzej Siewior wrote:
>>>  	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.

That's not a big deal, every QEMU supports every kernel and vice versa.

Paolo