From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jim Mattson Subject: [PATCH] kvm: x86: Disallow illegal IA32_APIC_BASE MSR values Date: Tue, 8 Aug 2017 16:27:26 -0700 Message-ID: <20170808232726.118570-1-jmattson@google.com> Cc: Jim Mattson To: kvm@vger.kernel.org Return-path: Received: from mail-pg0-f53.google.com ([74.125.83.53]:35551 "EHLO mail-pg0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752143AbdHHX2K (ORCPT ); Tue, 8 Aug 2017 19:28:10 -0400 Received: by mail-pg0-f53.google.com with SMTP id v189so20672312pgd.2 for ; Tue, 08 Aug 2017 16:28:10 -0700 (PDT) Sender: kvm-owner@vger.kernel.org List-ID: Host-initiated writes to the IA32_APIC_BASE MSR do not have to follow local APIC state transition constraints, but the value written must be valid. Signed-off-by: Jim Mattson --- arch/x86/kvm/x86.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index d734aa8c5b4f..fb786d9feef1 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -313,10 +313,11 @@ int kvm_set_apic_base(struct kvm_vcpu *vcpu, struct msr_data *msr_info) u64 reserved_bits = ((~0ULL) << cpuid_maxphyaddr(vcpu)) | 0x2ff | (guest_cpuid_has_x2apic(vcpu) ? 0 : X2APIC_ENABLE); + if ((msr_info->data & reserved_bits) != 0 || + new_state == X2APIC_ENABLE) + return 1; if (!msr_info->host_initiated && - ((msr_info->data & reserved_bits) != 0 || - new_state == X2APIC_ENABLE || - (new_state == MSR_IA32_APICBASE_ENABLE && + ((new_state == MSR_IA32_APICBASE_ENABLE && old_state == (MSR_IA32_APICBASE_ENABLE | X2APIC_ENABLE)) || (new_state == (MSR_IA32_APICBASE_ENABLE | X2APIC_ENABLE) && old_state == 0))) @@ -7444,7 +7445,8 @@ int kvm_arch_vcpu_ioctl_set_sregs(struct kvm_vcpu *vcpu, kvm_x86_ops->set_efer(vcpu, sregs->efer); apic_base_msr.data = sregs->apic_base; apic_base_msr.host_initiated = true; - kvm_set_apic_base(vcpu, &apic_base_msr); + if (kvm_set_apic_base(vcpu, &apic_base_msr)) + return -EINVAL; mmu_reset_needed |= kvm_read_cr0(vcpu) != sregs->cr0; kvm_x86_ops->set_cr0(vcpu, sregs->cr0); -- 2.14.0.434.g98096fd7a8-goog