From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752134AbaHSIeg (ORCPT ); Tue, 19 Aug 2014 04:34:36 -0400 Received: from mx1.redhat.com ([209.132.183.28]:39623 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751694AbaHSIed (ORCPT ); Tue, 19 Aug 2014 04:34:33 -0400 Message-ID: <53F30C0C.9040601@redhat.com> Date: Tue, 19 Aug 2014 10:34:20 +0200 From: Paolo Bonzini User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.7.0 MIME-Version: 1.0 To: Wanpeng Li CC: Jan Kiszka , Marcelo Tosatti , Gleb Natapov , Bandan Das , Zhang Yang , kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4] KVM: nVMX: nested TPR shadow/threshold emulation References: <1408437040-49181-1-git-send-email-wanpeng.li@linux.intel.com> In-Reply-To: <1408437040-49181-1-git-send-email-wanpeng.li@linux.intel.com> Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Il 19/08/2014 10:30, Wanpeng Li ha scritto: > + if (vmx->nested.virtual_apic_page) > + nested_release_page(vmx->nested.virtual_apic_page); > + vmx->nested.virtual_apic_page = > + nested_get_page(vcpu, vmcs12->virtual_apic_page_addr); > + if (!vmx->nested.virtual_apic_page) > + exec_control &= > + ~CPU_BASED_TPR_SHADOW; > + else > + vmcs_write64(VIRTUAL_APIC_PAGE_ADDR, > + page_to_phys(vmx->nested.virtual_apic_page)); > + > + /* > + * If CR8 load exits are enabled, CR8 store exits are enabled, > + * and virtualize APIC access is disabled, the processor would > + * never notice. Doing it unconditionally is not correct, but > + * it is the simplest thing. > + */ > + if (!(exec_control & CPU_BASED_TPR_SHADOW) && > + !((exec_control & CPU_BASED_CR8_LOAD_EXITING) && > + (exec_control & CPU_BASED_CR8_STORE_EXITING))) > + nested_vmx_failValid(vcpu, VMXERR_ENTRY_INVALID_CONTROL_FIELD); > + You aren't checking "virtualize APIC access" here, but the comment mentions it. As the comment says, failing the entry unconditionally could be the simplest thing, which means moving the nested_vmx_failValid call inside the "if (!vmx->nested.virtual_apic_page)". If you want to check all of CR8_LOAD/CR8_STORE/VIRTUALIZE_APIC_ACCESS, please mention in the comment that failing the vm entry is _not_ what the processor does but it's basically the only possibility we have. In that case, I would also place the "if" within the "if (!vmx->nested.virtual_apic_page)": it also simplifies the condition because you don't have to check CPU_BASED_TPR_SHADOW anymore. You can send v5 with these changes, and I'll apply it for 3.18. Thanks! Paolo