From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH v3 1/6] KVM: nVMX: Replace kvm_set_cr0 with vmx_set_cr0 in load_vmcs12_host_state Date: Tue, 10 Sep 2013 15:26:16 +0200 Message-ID: <522F1DF8.3030406@redhat.com> References: <93ce2376292d9d6fc7a4f4d53919b0a07d4e7859.1375971992.git.jan.kiszka@siemens.com> <20130902082136.GM22899@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: Gleb Natapov , Jan Kiszka , kvm , Xiao Guangrong , Jun Nakajima , Yang Zhang To: Arthur Chunqi Li Return-path: Received: from mx1.redhat.com ([209.132.183.28]:59334 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751785Ab3IJN01 (ORCPT ); Tue, 10 Sep 2013 09:26:27 -0400 In-Reply-To: Sender: kvm-owner@vger.kernel.org List-ID: Il 10/09/2013 15:14, Arthur Chunqi Li ha scritto: >> On Thu, Aug 08, 2013 at 04:26:28PM +0200, Jan Kiszka wrote: >>> >> Likely a typo, but a fatal one as kvm_set_cr0 performs checks on the >> > Not a typo :) That what Avi asked for do during initial nested VMX >> > review: http://markmail.org/message/hhidqyhbo2mrgxxc >> > >> > But there is at least one transition check that kvm_set_cr0() does that >> > should not be done during vmexit emulation, namely CS.L bit check, so I >> > tend to agree that kvm_set_cr0() is not appropriate here, at lest not as >> > it is. But can we skip other checks kvm_set_cr0() does? For instance >> > what prevents us from loading CR0.PG = 1 EFER.LME = 1 and CR4.PAE = 0 >> > during nested vmexit? What _should_ prevent it is vmentry check from >> > 26.2.4 >> > >> > If the "host address-space size" VM-exit control is 1, the following >> > must hold: >> > - Bit 5 of the CR4 field (corresponding to CR4.PAE) is 1. > Hi Jan and Gleb, > Our nested VMX testing framework may not support such testing modes. > Here we need to catch the failed result (ZF flag) close to vmresume, > but vmresume/vmlaunch is well encapsulated in our framework. If we > simply write a vmresume inline function, the VMX will act unexpectedly > when it doesn't cause "vmresume fail". > > Do you have any ideas about this? You could have a "failed entry" handler that by default would be simply return launched ? VMX_TEST_RESUME_ERR : VMX_TEST_LAUNCH_ERR For this test, it would return VMX_TEST_RESUME or VMX_TEST_VMEXIT if it fails, while the "regular" exit_handler would return VMX_TEST_EXIT. Paolo