Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Thu, 10 Feb 2022 22:49:57 +0000
From:   Sean Christopherson <seanjc@google.com>
To:     Paolo Bonzini <pbonzini@redhat.com>
Cc:     linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
        vkuznets@redhat.com, mlevitsk@redhat.com, dmatlack@google.com,
        stable@vger.kernel.org
Subject: Re: [PATCH 01/12] KVM: x86: host-initiated EFER.LME write affects
 the MMU
Message-ID: <YgWWldQdqHBMdzA6@google.com>
References: <20220209170020.1775368-1-pbonzini@redhat.com>
 <20220209170020.1775368-2-pbonzini@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20220209170020.1775368-2-pbonzini@redhat.com>
Precedence: bulk

On Wed, Feb 09, 2022, Paolo Bonzini wrote:
> While the guest runs, EFER.LME cannot change unless CR0.PG is clear, and therefore
> EFER.NX is the only bit that can affect the MMU role.  However, set_efer accepts
> a host-initiated change to EFER.LME even with CR0.PG=1.  In that case, the
> MMU has to be reset.
> 
> Fixes: 11988499e62b ("KVM: x86: Skip EFER vs. guest CPUID checks for host-initiated writes")
> Cc: stable@vger.kernel.org
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---

Ugh, but KVM_SET_SREGS handles this... It's basically KVM's equivalent of VMX putting
EFER in the VMCS, but then also allowing EFER in the load/store lists.

Reviewed-by: Sean Christopherson <seanjc@google.com>