Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754685AbbEZN3l (ORCPT ); Tue, 26 May 2015 09:29:41 -0400 Received: from mx1.redhat.com ([209.132.183.28]:43030 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752195AbbEZN3i (ORCPT ); Tue, 26 May 2015 09:29:38 -0400 Message-ID: <55644D12.6020301@redhat.com> Date: Tue, 26 May 2015 12:38:10 +0200 From: Paolo Bonzini User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.6.0 MIME-Version: 1.0 To: =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , linux-kernel@vger.kernel.org CC: kvm@vger.kernel.org Subject: Re: [PATCH] KVM: x86: preserve x2APIC LDR on INIT References: <1432315330-20872-1-git-send-email-rkrcmar@redhat.com> In-Reply-To: <1432315330-20872-1-git-send-email-rkrcmar@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1473 Lines: 44 On 22/05/2015 19:22, Radim Krčmář wrote: > Logical x2APIC stops working if we rewrite it with zeros. > The best references are SDM April 2015: 10.12.10.1 Logical Destination > Mode in x2APIC Mode > > [...], the LDR are initialized by hardware based on the value of > x2APIC ID upon x2APIC state transitions. > > and SDM April 2015: 10.12.10.2 Deriving Logical x2APIC ID from the Local > x2APIC ID > > The LDR initialization occurs whenever the x2APIC mode is enabled > > Signed-off-by: Radim Krčmář > --- > arch/x86/kvm/lapic.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c > index c2a7d8a7a414..c789e00dfa8b 100644 > --- a/arch/x86/kvm/lapic.c > +++ b/arch/x86/kvm/lapic.c > @@ -1594,7 +1594,8 @@ void kvm_lapic_reset(struct kvm_vcpu *vcpu, bool init_event) > apic_set_reg(apic, APIC_DFR, 0xffffffffU); > apic_set_spiv(apic, 0xff); > apic_set_reg(apic, APIC_TASKPRI, 0); > - kvm_apic_set_ldr(apic, 0); > + if (!apic_x2apic_mode(apic)) > + kvm_apic_set_ldr(apic, 0); > apic_set_reg(apic, APIC_ESR, 0); > apic_set_reg(apic, APIC_ICR, 0); > apic_set_reg(apic, APIC_ICR2, 0); > Applied, thanks. Paolo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/