From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: [PATCH v2] KVM: x86: Prevent exposing TSC deadline timer feature in the absence of in-kernel APIC Date: Wed, 21 Dec 2011 11:25:39 +0100 Message-ID: <4EF1B423.8050707@siemens.com> References: <4EF1146D.208@siemens.com> <4EF1B081.3010109@siemens.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Kernel development list , Marcelo Tosatti , "Garrett D'Amore" , kvm To: Linus Torvalds , Alexey Zaytsev , "Liu, Jinsong" , Avi Kivity Return-path: In-Reply-To: <4EF1B081.3010109@siemens.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org We must not report the TSC deadline timer feature on our own when user space provides the APIC as we have no clue about its features. Signed-off-by: Jan Kiszka --- Changes in v2: - reorganized code to make the flow clearer arch/x86/kvm/cpuid.c | 18 ++++++++---------- 1 files changed, 8 insertions(+), 10 deletions(-) diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 230f713..b7cdd3b 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -27,7 +27,6 @@ void kvm_update_cpuid(struct kvm_vcpu *vcpu) { struct kvm_cpuid_entry2 *best; struct kvm_lapic *apic = vcpu->arch.apic; - u32 timer_mode_mask; best = kvm_find_cpuid_entry(vcpu, 1, 0); if (!best) @@ -40,15 +39,14 @@ void kvm_update_cpuid(struct kvm_vcpu *vcpu) best->ecx |= bit(X86_FEATURE_OSXSAVE); } - if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL && - best->function == 0x1) { - best->ecx |= bit(X86_FEATURE_TSC_DEADLINE_TIMER); - timer_mode_mask = 3 << 17; - } else - timer_mode_mask = 1 << 17; - - if (apic) - apic->lapic_timer.timer_mode_mask = timer_mode_mask; + if (apic) { + if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL && + best->function == 0x1) { + best->ecx |= bit(X86_FEATURE_TSC_DEADLINE_TIMER); + apic->lapic_timer.timer_mode_mask = 3 << 17; + } else + apic->lapic_timer.timer_mode_mask = 1 << 17; + } kvm_pmu_cpuid_update(vcpu); } -- 1.7.3.4