From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9543AAD49 for ; Wed, 4 Jan 2023 16:13:32 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id EE0E4C433F0; Wed, 4 Jan 2023 16:13:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1672848812; bh=/+RtLJrw83pOsRnIAVJD9SSkZloBC3qiRoY0p3tK/fc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GjibMJY126gLRDilx9wVi/0tsVsdCbAVx3k500lLPIlpmf11T5VZUomdrR+uFn50r 9nvy+iSXIG6cEc1ESSVkjp0POZ7J/oObQnm1++4rgnytaIfGuiY07EZcn07TOEPRzg IjSbXki2d38+/57Cj3g0thxsJGP4QgiTuXh3QguY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Yuan ZhaoXiong , Alejandro Jimenez , Paolo Bonzini Subject: [PATCH 6.1 084/207] KVM: x86: fix APICv/x2AVIC disabled when vm reboot by itself Date: Wed, 4 Jan 2023 17:05:42 +0100 Message-Id: <20230104160514.602074783@linuxfoundation.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230104160511.905925875@linuxfoundation.org> References: <20230104160511.905925875@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Yuan ZhaoXiong commit ef40757743b47cc95de9b4ed41525c94f8dc73d9 upstream. When a VM reboots itself, the reset process will result in an ioctl(KVM_SET_LAPIC, ...) to disable x2APIC mode and set the xAPIC id of the vCPU to its default value, which is the vCPU id. That will be handled in KVM as follows: kvm_vcpu_ioctl_set_lapic kvm_apic_set_state kvm_lapic_set_base => disable X2APIC mode kvm_apic_state_fixup kvm_lapic_xapic_id_updated kvm_xapic_id(apic) != apic->vcpu->vcpu_id kvm_set_apicv_inhibit(APICV_INHIBIT_REASON_APIC_ID_MODIFIED) memcpy(vcpu->arch.apic->regs, s->regs, sizeof(*s)) => update APIC_ID When kvm_apic_set_state invokes kvm_lapic_set_base to disable x2APIC mode, the old 32-bit x2APIC id is still present rather than the 8-bit xAPIC id. kvm_lapic_xapic_id_updated will set the APICV_INHIBIT_REASON_APIC_ID_MODIFIED bit and disable APICv/x2AVIC. Instead, kvm_lapic_xapic_id_updated must be called after APIC_ID is changed. In fact, this fixes another small issue in the code in that potential changes to a vCPU's xAPIC ID need not be tracked for KVM_GET_LAPIC. Fixes: 3743c2f02517 ("KVM: x86: inhibit APICv/AVIC on changes to APIC ID or APIC base") Signed-off-by: Yuan ZhaoXiong Message-Id: <1669984574-32692-1-git-send-email-yuanzhaoxiong@baidu.com> Cc: stable@vger.kernel.org Reported-by: Alejandro Jimenez Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/lapic.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -2722,8 +2722,6 @@ static int kvm_apic_state_fixup(struct k icr = __kvm_lapic_get_reg64(s->regs, APIC_ICR); __kvm_lapic_set_reg(s->regs, APIC_ICR2, icr >> 32); } - } else { - kvm_lapic_xapic_id_updated(vcpu->arch.apic); } return 0; @@ -2759,6 +2757,9 @@ int kvm_apic_set_state(struct kvm_vcpu * } memcpy(vcpu->arch.apic->regs, s->regs, sizeof(*s)); + if (!apic_x2apic_mode(apic)) + kvm_lapic_xapic_id_updated(apic); + atomic_set_release(&apic->vcpu->kvm->arch.apic_map_dirty, DIRTY); kvm_recalculate_apic_map(vcpu->kvm); kvm_apic_set_version(vcpu);