From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH v2 4/4] kvm: vmx: fix VMfailValid when write vmcs02/vmcs01 Date: Thu, 04 Dec 2014 15:28:18 +0100 Message-ID: <54806F82.5090806@redhat.com> References: <1417691470-5221-1-git-send-email-wanpeng.li@linux.intel.com> <1417691470-5221-4-git-send-email-wanpeng.li@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 8bit Cc: Nadav Amit , rkrcmar@redhat.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org To: Wanpeng Li Return-path: In-Reply-To: <1417691470-5221-4-git-send-email-wanpeng.li@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 04/12/2014 12:11, Wanpeng Li wrote: > SDM 30.3 VMWRITE > > ELSIF secondary source operand does not correspond to any VMCS field > THEN VMfailValid(VMREAD/VMWRITE from/to unsupported VMCS component); > > We can't suppose L1 VMM expose MPX to L2 just if L0 support MPX. There > will be VMfailValid if L0 doesn't support MPX and L1 expose MPX to L2 > when L0 writes vmcs02/vmcs01, in addition, there is no need to read > GUEST_BNDCFGS if L1 VMM doesn't expose it to L2. This patch fix it by > both check L0 support xsaves and L1 expose MPX to L2. Did you have a reproducer for this? It should not be needed, because the bndcfgs entry/exit controls are hidden from nested_vmx_exit_ctls_high and nested_vmx_entry_ctls_high if !vmx_mpx_supported(). This hunk is also not correct: > - if (vmx_mpx_supported()) > + if (vmx_mpx_supported() && > + (vmcs12->vm_entry_controls & VM_ENTRY_LOAD_BNDCFGS)) > vmcs12->guest_bndcfgs = vmcs_read64(GUEST_BNDCFGS); > if (nested_cpu_has_xsaves(vmcs12)) > vmcs12->xss_exit_bitmap = vmcs_read64(XSS_EXIT_BITMAP); because there is no "save BNDCFGS" exit control; the guest BNDCFGS is saved unconditionally into the vmcs. Paolo