linux-kernel - Re: [PATCH] KVM: nVMX: Fix CR4 after VMLAUNCH/VMRESUME failure

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Date:   Thu, 8 Feb 2018 17:40:37 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Jim Mattson <jmattson@...gle.com>, Wanpeng Li <kernellwp@...il.com>
Cc:     kvm list <kvm@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Radim Krcmar <rkrcmar@...hat.com>
Subject: Re: [PATCH] KVM: nVMX: Fix CR4 after VMLAUNCH/VMRESUME failure

On 08/02/2018 16:54, Jim Mattson wrote:
> On Thu, Feb 8, 2018 at 7:29 AM, Jim Mattson <jmattson@...gle.com> wrote:
>> Similarly, the correct L1 CR4 value should be in vmcs01's CR4
>> read shadow field.
> Sorry; that's wrong. L1's CR4 value has to be reconstructed from the
> vmcs01 guest CR4 field and CR4 shadow field using the cr4 guest/host
> mask. But there is no way to get it from any field(s) in vmcs12.

Now that we have the prepare_vmcs02_full/prepare_vmcs02 split, we
probably should do more checks in there, and not rely on the processor
anymore.

Paolo