From mboxrd@z Thu Jan 1 00:00:00 1970 From: Orit Wasserman Subject: Re: [PATCH v5 02/14] nEPT: Fix cr3 handling in nested exit and entry Date: Thu, 01 Aug 2013 14:28:43 +0300 Message-ID: <51FA466B.7090703@redhat.com> References: <1375282131-9713-1-git-send-email-gleb@redhat.com> <1375282131-9713-3-git-send-email-gleb@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org, Xiao Guangrong , Jun Nakajima , Yang Zhang , pbonzini@redhat.com To: Gleb Natapov Return-path: Received: from mx1.redhat.com ([209.132.183.28]:30642 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751177Ab3HAL1k (ORCPT ); Thu, 1 Aug 2013 07:27:40 -0400 In-Reply-To: <1375282131-9713-3-git-send-email-gleb@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 07/31/2013 05:48 PM, Gleb Natapov 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 > Signed-off-by: Yang Zhang > Signed-off-by: Gleb Natapov > --- > arch/x86/kvm/vmx.c | 26 ++++++++++++++++++++++++++ > 1 file changed, 26 insertions(+) > > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index 27efa6a..4e98764 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -7595,6 +7595,16 @@ static void prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12) > kvm_set_cr3(vcpu, vmcs12->guest_cr3); > kvm_mmu_reset_context(vcpu); > > + /* > + * L1 may access the L2's PDPTR, so save them to construct vmcs12 > + */ > + 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); > } > @@ -7917,6 +7927,22 @@ 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. > + * > + * Additionally, restore L2's PDPTR to vmcs12. > + */ > + if (enable_ept) { > + vmcs12->guest_cr3 = vmcs_read64(GUEST_CR3); > + 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); > Reviewed-by: Orit Wasserman