From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joerg Roedel Subject: Re: [PATCH 3/8] KVM: SVM: Sync cr0 and cr3 to kvm state before nested handling Date: Fri, 23 Apr 2010 16:17:06 +0200 Message-ID: <20100423141706.GE31537@amd.com> References: <1271932394-13968-1-git-send-email-joerg.roedel@amd.com> <1271932394-13968-4-git-send-email-joerg.roedel@amd.com> <894CCCC7-6E35-499D-9EF6-57A9123B969C@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Cc: Avi Kivity , Marcelo Tosatti , kvm@vger.kernel.org, linux-kernel@vger.kernel.org To: Alexander Graf Return-path: Received: from va3ehsobe002.messaging.microsoft.com ([216.32.180.12]:19299 "EHLO VA3EHSOBE002.bigfish.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751434Ab0DWOR1 (ORCPT ); Fri, 23 Apr 2010 10:17:27 -0400 Content-Disposition: inline In-Reply-To: <894CCCC7-6E35-499D-9EF6-57A9123B969C@suse.de> Sender: kvm-owner@vger.kernel.org List-ID: On Fri, Apr 23, 2010 at 03:50:20PM +0200, Alexander Graf wrote: > > On 22.04.2010, at 12:33, Joerg Roedel wrote: > > > This patch syncs cr0 and cr3 from the vmcb to the kvm state > > before nested intercept handling is done. This allows to > > simplify the vmexit path. > > > > Signed-off-by: Joerg Roedel > > --- > > arch/x86/kvm/svm.c | 15 ++++++--------- > > 1 files changed, 6 insertions(+), 9 deletions(-) > > > > diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c > > index c480d7f..5ad9d80 100644 > > --- a/arch/x86/kvm/svm.c > > +++ b/arch/x86/kvm/svm.c > > @@ -1799,10 +1799,7 @@ static int nested_svm_vmexit(struct vcpu_svm *svm) > > nested_vmcb->save.gdtr = vmcb->save.gdtr; > > nested_vmcb->save.idtr = vmcb->save.idtr; > > nested_vmcb->save.cr0 = kvm_read_cr0(&svm->vcpu); > > - if (npt_enabled) > > - nested_vmcb->save.cr3 = vmcb->save.cr3; > > - else > > - nested_vmcb->save.cr3 = svm->vcpu.arch.cr3; > > + nested_vmcb->save.cr3 = svm->vcpu.arch.cr3; > > > Why don't we need this anymore again? Because arch.cr3 contains always the current l2-cr3. This wasn't the case before because the sync was done after the nested handling. But now we do it before a vmexit can happen and are safe to just use arch.cr3. Joerg