From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH 5/5] KVM: x86: BSP in MSR_IA32_APICBASE is writable Date: Mon, 30 Mar 2015 16:12:02 +0200 Message-ID: <551959B2.10503@redhat.com> References: <1427719163-5429-1-git-send-email-namit@cs.technion.ac.il> <1427719163-5429-6-git-send-email-namit@cs.technion.ac.il> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org To: Nadav Amit , mtosatti@redhat.com Return-path: Received: from mx1.redhat.com ([209.132.183.28]:57671 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751398AbbC3OMH (ORCPT ); Mon, 30 Mar 2015 10:12:07 -0400 In-Reply-To: <1427719163-5429-6-git-send-email-namit@cs.technion.ac.il> Sender: kvm-owner@vger.kernel.org List-ID: On 30/03/2015 14:39, Nadav Amit wrote: > After reset, the CPU can change the BSP, which will be used upon INIT. Reset > should return the BSP which QEMU asked for, and therefore handled accordingly. > > To quote: "If the MP protocol has completed and a BSP is chosen, subsequent > INITs (either to a specific processor or system wide) do not cause the MP > protocol to be repeated." > [Intel SDM 8.4.2: MP Initialization Protocol Requirements and Restrictions] > > Signed-off-by: Nadav Amit Please provide a kvm-unit-tests testcase for this. Paolo > --- > arch/x86/kvm/lapic.c | 2 -- > arch/x86/kvm/svm.c | 2 +- > arch/x86/kvm/vmx.c | 2 +- > include/linux/kvm_host.h | 7 ++++++- > 4 files changed, 8 insertions(+), 5 deletions(-) > > diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c > index 17da6fc..b0dbf68 100644 > --- a/arch/x86/kvm/lapic.c > +++ b/arch/x86/kvm/lapic.c > @@ -1498,8 +1498,6 @@ void kvm_lapic_set_base(struct kvm_vcpu *vcpu, u64 value) > return; > } > > - if (!kvm_vcpu_is_bsp(apic->vcpu)) > - value &= ~MSR_IA32_APICBASE_BSP; > vcpu->arch.apic_base = value; > > /* update jump label if enable bit changes */ > diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c > index 1ef4c0d..ef5bf21 100644 > --- a/arch/x86/kvm/svm.c > +++ b/arch/x86/kvm/svm.c > @@ -1261,7 +1261,7 @@ static struct kvm_vcpu *svm_create_vcpu(struct kvm *kvm, unsigned int id) > > svm->vcpu.arch.apic_base = APIC_DEFAULT_PHYS_BASE | > MSR_IA32_APICBASE_ENABLE; > - if (kvm_vcpu_is_bsp(&svm->vcpu)) > + if (kvm_vcpu_is_reset_bsp(&svm->vcpu)) > svm->vcpu.arch.apic_base |= MSR_IA32_APICBASE_BSP; > > svm_init_osvw(&svm->vcpu); > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index 8aee6db..7e370b2 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -4709,7 +4709,7 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) > if (!init_event) { > apic_base_msr.data = APIC_DEFAULT_PHYS_BASE | > MSR_IA32_APICBASE_ENABLE; > - if (kvm_vcpu_is_bsp(&vmx->vcpu)) > + if (kvm_vcpu_is_reset_bsp(&vmx->vcpu)) > apic_base_msr.data |= MSR_IA32_APICBASE_BSP; > apic_base_msr.host_initiated = true; > kvm_set_apic_base(&vmx->vcpu, &apic_base_msr); > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > index 0f574eb..8365cae 100644 > --- a/include/linux/kvm_host.h > +++ b/include/linux/kvm_host.h > @@ -968,11 +968,16 @@ static inline int kvm_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args) > #endif /* CONFIG_HAVE_KVM_EVENTFD */ > > #ifdef CONFIG_KVM_APIC_ARCHITECTURE > -static inline bool kvm_vcpu_is_bsp(struct kvm_vcpu *vcpu) > +static inline bool kvm_vcpu_is_reset_bsp(struct kvm_vcpu *vcpu) > { > return vcpu->kvm->bsp_vcpu_id == vcpu->vcpu_id; > } > > +static inline bool kvm_vcpu_is_bsp(struct kvm_vcpu *vcpu) > +{ > + return (vcpu->arch.apic_base & MSR_IA32_APICBASE_BSP) != 0; > +} > + > bool kvm_vcpu_compatible(struct kvm_vcpu *vcpu); > > #else >