From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756423AbaGQJE2 (ORCPT ); Thu, 17 Jul 2014 05:04:28 -0400 Received: from mail-we0-f169.google.com ([74.125.82.169]:49441 "EHLO mail-we0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755737AbaGQJEX (ORCPT ); Thu, 17 Jul 2014 05:04:23 -0400 Message-ID: <53C79182.1040408@redhat.com> Date: Thu, 17 Jul 2014 11:04:02 +0200 From: Paolo Bonzini User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.6.0 MIME-Version: 1.0 To: Wanpeng Li , Jan Kiszka CC: Marcelo Tosatti , Gleb Natapov , Bandan Das , Zhang Yang , Hu Robert , kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 3/3] KVM: nVMX: Fix vmptrld fail and vmwrite error when L1 goes down References: <1405573011-41330-1-git-send-email-wanpeng.li@linux.intel.com> <1405573011-41330-3-git-send-email-wanpeng.li@linux.intel.com> <53C78FA9.5000303@redhat.com> In-Reply-To: <53C78FA9.5000303@redhat.com> X-Enigmail-Version: 1.6 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Il 17/07/2014 10:56, Paolo Bonzini ha scritto: > Il 17/07/2014 06:56, Wanpeng Li ha scritto: >> This bug can be trigger by L1 goes down directly w/ enable_shadow_vmcs. >> >> [ 6413.158950] kvm: vmptrld (null)/780000000000 failed >> [ 6413.158954] vmwrite error: reg 401e value 4 (err 1) >> [ 6413.158957] CPU: 0 PID: 4840 Comm: qemu-system-x86 Tainted: >> G OE 3.16.0kvm+ #2 >> [ 6413.158958] Hardware name: Dell Inc. OptiPlex 9020/0DNKMN, BIOS A05 >> 12/05/2013 >> [ 6413.158959] 0000000000000003 ffff880210c9fb58 ffffffff81741de9 >> ffff8800d7433f80 >> [ 6413.158960] ffff880210c9fb68 ffffffffa059fa08 ffff880210c9fb78 >> ffffffffa05938bf >> [ 6413.158962] ffff880210c9fba8 ffffffffa059a97f ffff8800d7433f80 >> 0000000000000003 >> [ 6413.158963] Call Trace: >> [ 6413.158968] [] dump_stack+0x45/0x56 >> [ 6413.158972] [] vmwrite_error+0x2c/0x2e [kvm_intel] >> [ 6413.158974] [] vmcs_writel+0x1f/0x30 [kvm_intel] >> [ 6413.158976] [] free_nested.part.73+0x5f/0x170 >> [kvm_intel] >> [ 6413.158978] [] vmx_free_vcpu+0x33/0x70 [kvm_intel] >> [ 6413.158991] [] kvm_arch_vcpu_free+0x44/0x50 [kvm] >> [ 6413.158998] [] kvm_arch_destroy_vm+0xf2/0x1f0 [kvm] >> >> Commit 26a865 (KVM: VMX: fix use after free of vmx->loaded_vmcs) fix >> the use >> after free bug by move free_loaded_vmcs() before free_nested(), >> however, this >> lead to free loaded_vmcs->vmcs premature and vmptrld load a NULL >> pointer during >> sync shadow vmcs to vmcs12. In addition, vmwrite which used to disable >> shadow >> vmcs and reset VMCS_LINK_POINTER failed since there is no valid >> current-VMCS. >> This patch fix it by skipping sync shadow vmcs and reset vmcs field >> for L1 >> destroy since they will be reinitialized after L1 recreate. >> >> Signed-off-by: Wanpeng Li >> --- >> arch/x86/kvm/vmx.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c >> index fbce89e..2b28da7 100644 >> --- a/arch/x86/kvm/vmx.c >> +++ b/arch/x86/kvm/vmx.c >> @@ -6113,9 +6113,9 @@ static void free_nested(struct vcpu_vmx *vmx) >> return; >> vmx->nested.vmxon = false; >> if (vmx->nested.current_vmptr != -1ull) { >> - nested_release_vmcs12(vmx); >> vmx->nested.current_vmptr = -1ull; >> vmx->nested.current_vmcs12 = NULL; >> + nested_release_vmcs12(vmx); >> } >> if (enable_shadow_vmcs) >> free_vmcs(vmx->nested.current_shadow_vmcs); >> > > This looks good, I'll apply it to kvm/master. Hmm, on second thought the lifetimes of the VMCSes are a total mess. Let me look more at this. Paolo