linux-kernel - Re: [PATCH] KVM: x86: cleanup CR3 reserved bits checks

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Message-ID: <7077098b-d5f0-afe1-9924-def460d06f96@redhat.com>
Date:   Wed, 3 Feb 2021 09:28:07 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Subject: Re: [PATCH] KVM: x86: cleanup CR3 reserved bits checks

On 02/02/21 19:34, Sean Christopherson wrote:
> On Tue, Feb 02, 2021, Paolo Bonzini wrote:
>> If not in long mode, the low bits of CR3 are reserved but not enforced to
>> be zero, so remove those checks.  If in long mode, however, the MBZ bits
>> extend down to the highest physical address bit of the guest, excluding
>> the encryption bit.
>>
>> Make the checks consistent with the above, and match them between
>> nested_vmcb_checks and KVM_SET_SREGS.
>>
> Fixes + Cc:stable@?

Difficult to say what it fixes, it's been there forever for KVM_SET_SREGS.

For the nSVM part I'll go with

Fixes: 761e41693465 ("KVM: nSVM: Check that MBZ bits in CR3 and CR4 are 
not set on vmrun of nested guests")

Paolo

>> Signed-off-by: Paolo Bonzini<pbonzini@...hat.com>
> Reviewed-by: Sean Christopherson<seanjc@...gle.com>  
>