From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gleb Natapov Subject: Re: [PATCH v3 06/13] nEPT: Fix cr3 handling in nested exit and entry Date: Wed, 12 Jun 2013 15:42:34 +0300 Message-ID: <20130612124234.GN4725@redhat.com> References: <1368939152-11406-1-git-send-email-jun.nakajima@intel.com> <1368939152-11406-6-git-send-email-jun.nakajima@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: kvm@vger.kernel.org, Paolo Bonzini To: Jun Nakajima Return-path: Received: from mx1.redhat.com ([209.132.183.28]:32783 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751483Ab3FLMmj (ORCPT ); Wed, 12 Jun 2013 08:42:39 -0400 Content-Disposition: inline In-Reply-To: <1368939152-11406-6-git-send-email-jun.nakajima@intel.com> Sender: kvm-owner@vger.kernel.org List-ID: On Sat, May 18, 2013 at 09:52:25PM -0700, Jun Nakajima wrote: > From: Nadav Har'El > > The existing code for handling cr3 and related VMCS fields during nested > exit and entry wasn't correct in all cases: > > If L2 is allowed to control cr3 (and this is indeed the case in nested EPT), > during nested exit we must copy the modified cr3 from vmcs02 to vmcs12, and > we forgot to do so. This patch adds this copy. > > If L0 isn't controlling cr3 when running L2 (i.e., L0 is using EPT), and > whoever does control cr3 (L1 or L2) is using PAE, the processor might have > saved PDPTEs and we should also save them in vmcs12 (and restore later). > > Signed-off-by: Nadav Har'El > Signed-off-by: Jun Nakajima > Signed-off-by: Xinhao Xu > --- > arch/x86/kvm/vmx.c | 30 ++++++++++++++++++++++++++++++ > 1 file changed, 30 insertions(+) > > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index a88432f..b79efd4 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -7608,6 +7608,17 @@ static void prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12) > kvm_set_cr3(vcpu, vmcs12->guest_cr3); > kvm_mmu_reset_context(vcpu); > > + /* > + * Additionally, except when L0 is using shadow page tables, L1 or What this "Additionally" corresponds to? > + * L2 control guest_cr3 for L2, so they may also have saved PDPTEs > + */ > + if (enable_ept) { > + vmcs_write64(GUEST_PDPTR0, vmcs12->guest_pdptr0); > + vmcs_write64(GUEST_PDPTR1, vmcs12->guest_pdptr1); > + vmcs_write64(GUEST_PDPTR2, vmcs12->guest_pdptr2); > + vmcs_write64(GUEST_PDPTR3, vmcs12->guest_pdptr3); > + } > + > kvm_register_write(vcpu, VCPU_REGS_RSP, vmcs12->guest_rsp); > kvm_register_write(vcpu, VCPU_REGS_RIP, vmcs12->guest_rip); > } > @@ -7930,6 +7941,25 @@ static void prepare_vmcs12(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12) > vmcs12->guest_pending_dbg_exceptions = > vmcs_readl(GUEST_PENDING_DBG_EXCEPTIONS); > > + /* > + * In some cases (usually, nested EPT), L2 is allowed to change its > + * own CR3 without exiting. If it has changed it, we must keep it. > + * Of course, if L0 is using shadow page tables, GUEST_CR3 was defined > + * by L0, not L1 or L2, so we mustn't unconditionally copy it to vmcs12. > + */ > + if (enable_ept) Non need separate if for guest_cr3. Put it under if() below. > + vmcs12->guest_cr3 = vmcs_read64(GUEST_CR3); > + /* > + * Additionally, except when L0 is using shadow page tables, L1 or > + * L2 control guest_cr3 for L2, so save their PDPTEs > + */ > + if (enable_ept) { > + vmcs12->guest_pdptr0 = vmcs_read64(GUEST_PDPTR0); > + vmcs12->guest_pdptr1 = vmcs_read64(GUEST_PDPTR1); > + vmcs12->guest_pdptr2 = vmcs_read64(GUEST_PDPTR2); > + vmcs12->guest_pdptr3 = vmcs_read64(GUEST_PDPTR3); > + } > + > vmcs12->vm_entry_controls = > (vmcs12->vm_entry_controls & ~VM_ENTRY_IA32E_MODE) | > (vmcs_read32(VM_ENTRY_CONTROLS) & VM_ENTRY_IA32E_MODE); > -- > 1.8.1.2 -- Gleb.