From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH] KVM: VMX: Fix 32bit Windows blue screen with EPT Date: Thu, 30 Dec 2010 10:57:20 +0200 Message-ID: <4D1C4970.9000409@redhat.com> References: <1293698159-30452-1-git-send-email-sheng@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Marcelo Tosatti , kvm@vger.kernel.org To: Sheng Yang Return-path: Received: from mx1.redhat.com ([209.132.183.28]:43178 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753359Ab0L3I5Y (ORCPT ); Thu, 30 Dec 2010 03:57:24 -0500 In-Reply-To: <1293698159-30452-1-git-send-email-sheng@linux.intel.com> Sender: kvm-owner@vger.kernel.org List-ID: On 12/30/2010 10:35 AM, Sheng Yang wrote: > After CR0 is changed during VMExit, the result of kvm_read_cr3() may be > different. Commit d95bfcdd7cda4dfdac9588e684bc7c75794a075e "KVM: Fetch guest > cr3 from hardware on demand" caused 32bit Windows guest blue screen when using > with EPT. This patch fixes it by decache CR3 before CR0 change, for both > paging to nonpaging, and nonpaging to paging switch. > > Signed-off-by: Sheng Yang > --- > > But I haven't found the exactly point affected by this, any clue? > Can't see it either. > @@ -1921,8 +1921,7 @@ static void ept_update_paging_mode_cr0(unsigned long *hw_cr0, > unsigned long cr0, > struct kvm_vcpu *vcpu) > { > - ulong cr3; > - > + kvm_read_cr3(vcpu); Without this line, it fails? I think it's better to call vmx_decache_cr3() explicitly, since it explains what we're doing. vmx_decache_cr3 depends on arch.cr0, and we're changing that here. > 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? > } > > if (!(cr0& X86_CR0_WP)) -- error compiling committee.c: too many arguments to function