linux-kernel - Re: [PATCH 0/6] KVM: x86: KVM_SET

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Date:   Thu, 8 Oct 2020 10:59:51 -0700
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     stsp <stsp2@...dex.ru>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/6] KVM: x86: KVM_SET_SREGS.CR4 bug fixes and cleanup

On Thu, Oct 08, 2020 at 07:00:13PM +0300, stsp wrote:
> 07.10.2020 04:44, Sean Christopherson пишет:
> >Two bug fixes to handle KVM_SET_SREGS without a preceding KVM_SET_CPUID2.
> Hi Sean & KVM devs.
> 
> I tested the patches, and wherever I
> set VMXE in CR4, I now get
> KVM: KVM_SET_SREGS: Invalid argument
> Before the patch I was able (with many
> problems, but still) to set VMXE sometimes.
> 
> So its a NAK so far, waiting for an update. :)

IIRC, you said you were going to test on AMD?  Assuming that's correct, -EINVAL
is the expected behavior.  KVM was essentially lying before; it never actually
set CR4.VMXE in hardware, it just didn't properply detect the error and so VMXE
was set in KVM's shadow of the guest's CR4.