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From: Paolo Bonzini <pbonzini@redhat.com>
To: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: dgilbert@redhat.com, jmattson@google.com,
	linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Subject: Re: [PATCH] KVM: SVM: relax conditions for allowing MSR_IA32_SPEC_CTRL accesses
Date: Thu, 6 Feb 2020 15:21:37 +0100	[thread overview]
Message-ID: <1d7f50a2-3c3f-dd18-a635-aa4eaa757fa3@redhat.com> (raw)
In-Reply-To: <87v9ojg5r1.fsf@vitty.brq.redhat.com>

On 06/02/20 15:17, Vitaly Kuznetsov wrote:
> Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
> 
> but out of pure curiosity, why do we need these checks?
> 
> At least for the 'set' case right below them we have:
> 
>         if (data & ~kvm_spec_ctrl_valid_bits(vcpu))
>                  return 1;
> 
> so if guest will try using unsupported features it will #GP. So
> basically, these checks will only fire when reading/writing '0' and all
> features are missing, right? Do we care?

Probably not...  I just wanted the smallest possible change in semantics
for this patch, and the rest can be done equally on Intel and AMD.

Paolo


      reply	other threads:[~2020-02-06 14:21 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-05 15:13 Paolo Bonzini
2020-02-06 14:17 ` Vitaly Kuznetsov
2020-02-06 14:21   ` Paolo Bonzini [this message]

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