From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Jim Mattson <jmattson@google.com>
Cc: "Paolo Bonzini" <pbonzini@redhat.com>,
"Radim Krčmář" <rkrcmar@redhat.com>,
"Vitaly Kuznetsov" <vkuznets@redhat.com>,
"Wanpeng Li" <wanpengli@tencent.com>,
"Joerg Roedel" <joro@8bytes.org>,
"kvm list" <kvm@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
"Reto Buerki" <reet@codelabs.ch>
Subject: Re: [PATCH 1/2] KVM: nVMX: Always write vmcs02.GUEST_CR3 during nested VM-Enter
Date: Fri, 27 Sep 2019 07:22:58 -0700 [thread overview]
Message-ID: <20190927142258.GA24889@linux.intel.com> (raw)
In-Reply-To: <CALMp9eQVSg31uPy+RKAnsEZixtwix55CijC1DKKbmH-iNiJw9g@mail.gmail.com>
On Thu, Sep 26, 2019 at 04:39:28PM -0700, Jim Mattson wrote:
> On Thu, Sep 26, 2019 at 2:43 PM Sean Christopherson
> <sean.j.christopherson@intel.com> wrote:
> > - vmcs_writel(GUEST_CR3, guest_cr3);
> > + if (!skip_cr3)
> > + vmcs_writel(GUEST_CR3, guest_cr3);
>
> Is this part of the change necessary, or is it just an optimization to
> save a redundant VMWRITE?
Save the redundant VMWRITE. I also wanted to convey the idea that the
nested code is responsible for setting GUEST_CR3 to the correct value.
I'd be happy to add a comment to make the latter point explicit.
> > }
> >
> > int vmx_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
> > --
> > 2.22.0
> >
next prev parent reply other threads:[~2019-09-27 14:23 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-26 21:43 [PATCH 0/2] KVM: nVMX: Bug fix for consuming stale vmcs02.GUEST_CR3 Sean Christopherson
2019-09-26 21:43 ` [PATCH 1/2] KVM: nVMX: Always write vmcs02.GUEST_CR3 during nested VM-Enter Sean Christopherson
2019-09-26 23:39 ` Jim Mattson
2019-09-27 14:22 ` Sean Christopherson [this message]
2019-09-27 0:06 ` Liran Alon
2019-09-27 14:27 ` Sean Christopherson
2019-09-27 14:44 ` Liran Alon
2019-09-27 15:02 ` Sean Christopherson
2019-09-26 21:43 ` [PATCH 2/2] KVM: VMX: Skip GUEST_CR3 VMREAD+VMWRITE if the VMCS is up-to-date Sean Christopherson
2019-09-27 12:11 ` Vitaly Kuznetsov
2019-09-27 14:24 ` Sean Christopherson
2019-09-27 7:45 ` [PATCH 0/2] KVM: nVMX: Bug fix for consuming stale vmcs02.GUEST_CR3 Reto Buerki
2019-09-27 12:12 ` Vitaly Kuznetsov
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