From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753274AbbKCKrh (ORCPT ); Tue, 3 Nov 2015 05:47:37 -0500 Received: from mx1.redhat.com ([209.132.183.28]:59771 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752859AbbKCKrT (ORCPT ); Tue, 3 Nov 2015 05:47:19 -0500 Subject: Re: [PATCH] KVM: x86: fix eflags state following processor init/reset To: Nadav Amit , Wanpeng Li References: <287435CB-DC24-4E59-9320-A8F75DAA5555@gmail.com> Cc: kvm list , Linux Kernel Mailing List From: Paolo Bonzini Message-ID: <563890B3.2090704@redhat.com> Date: Tue, 3 Nov 2015 11:47:15 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: <287435CB-DC24-4E59-9320-A8F75DAA5555@gmail.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 28/10/2015 09:10, Nadav Amit wrote: > Here are my 5 cents. Note that vmx_vcpu_reset calls: > > vmcs_writel(GUEST_RFLAGS, 0x02); > > (And the RFLAGS value is not cached by KVM, so no consistency problem should > occur.) > > You may want to change the value into constant or call a wrapper function > for setting RFLAGS, but I don’t see something broken in the functionality. I agree. Wanpeng, if this is just a cleanup, can you send v2 that removes or modifies the existing call to vmcs_writel? If there is a bug, can you write a unit test for it? It should be possible to test for the problem using INIT+SIPI on an AP. Thanks, Paolo > Regards, > Nadav > > Wanpeng Li wrote: > >> Ping, :-) >> On 10/21/15 2:28 PM, Wanpeng Li wrote: >>> Reference SDM 3.4.3: >>> >>> Following initialization of the processor (either by asserting the >>> RESET pin or the INIT pin), the state of the EFLAGS register is >>> 00000002H. >>> >>> However, the eflags fixed bit is not set and other bits are also not >>> cleared during the init/reset in kvm. >>> >>> This patch fix it by set eflags register to 00000002H following >>> initialization of the processor. >>> >>> Signed-off-by: Wanpeng Li >>> --- >>> arch/x86/kvm/vmx.c | 1 + >>> 1 file changed, 1 insertion(+) >>> >>> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c >>> index b680c2e..326f6ea 100644 >>> --- a/arch/x86/kvm/vmx.c >>> +++ b/arch/x86/kvm/vmx.c >>> @@ -4935,6 +4935,7 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) >>> vmx_set_efer(vcpu, 0); >>> vmx_fpu_activate(vcpu); >>> update_exception_bitmap(vcpu); >>> + vmx_set_rflags(vcpu, X86_EFLAGS_FIXED); >>> vpid_sync_context(vmx->vpid); >>> } >> >> -- >> To unsubscribe from this list: send the line "unsubscribe kvm" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html > >