From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sheng Yang Subject: Re: [PATCH] KVM: VMX: Fix 32bit Windows blue screen with EPT Date: Thu, 30 Dec 2010 17:20:23 +0800 Message-ID: <201012301720.23752.sheng@linux.intel.com> References: <1293698159-30452-1-git-send-email-sheng@linux.intel.com> <201012301705.28771.sheng@linux.intel.com> <4D1C4D6F.7030707@redhat.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: Marcelo Tosatti , kvm@vger.kernel.org To: Avi Kivity Return-path: Received: from mga03.intel.com ([143.182.124.21]:39444 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751105Ab0L3JSs (ORCPT ); Thu, 30 Dec 2010 04:18:48 -0500 In-Reply-To: <4D1C4D6F.7030707@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On Thursday 30 December 2010 17:14:23 Avi Kivity wrote: > On 12/30/2010 11:05 AM, Sheng Yang wrote: > > > > if (!(cr0& X86_CR0_PG)) { > > > > > > > > /* From paging/starting to nonpaging */ > > > > vmcs_write32(CPU_BASED_VM_EXEC_CONTROL, > > > > > > > > @@ -1937,11 +1936,8 @@ static void > > > > ept_update_paging_mode_cr0(unsigned long *hw_cr0, > > > > > > > > vmcs_read32(CPU_BASED_VM_EXEC_CONTROL)& > > > > > > > > ~(CPU_BASED_CR3_LOAD_EXITING | > > > > > > > > CPU_BASED_CR3_STORE_EXITING)); > > > > > > > > - /* Must fetch cr3 before updating cr0 */ > > > > - cr3 = kvm_read_cr3(vcpu); > > > > > > > > vcpu->arch.cr0 = cr0; > > > > vmx_set_cr4(vcpu, kvm_read_cr4(vcpu)); > > > > > > > > - vmx_set_cr3(vcpu, cr3); > > > > > > This is indeed bogus. But what ensures that we'll have the correct > > > GUEST_CR3 after enabling paging? > > > > In fact I don't understand why we need this line. All modification is for > > CR3 reading, why we need to set hardware CR3 again? It should be the > > same as when we don't have CR3 accessor I think. > > when cr0.pg=0 then we set GUEST_CR3=identity_pagetable. We don't want > that when we we switch to paging mode. I think kvm_mmu_reset_context() in kvm_set_cr0() should cover this? -- regards Yang, Sheng