From a0c9a822bf37e6282eb6006b407ec5aec22e08fb Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Wed, 11 Apr 2012 18:49:55 +0300 Subject: KVM: dont clear TMR on EOI Intel spec says that TMR needs to be set/cleared when IRR is set, but kvm also clears it on EOI. I did some tests on a real (AMD based) system, and I see same TMR values both before and after EOI, so I think it's a minor bug in kvm. This patch fixes TMR to be set/cleared on IRR set only as per spec. And now that we don't clear TMR, we can save an atomic read of TMR on EOI that's not propagated to ioapic, by checking whether ioapic needs a specific vector first and calculating the mode afterwards. Signed-off-by: Michael S. Tsirkin Signed-off-by: Marcelo Tosatti --- virt/kvm/ioapic.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) (limited to 'virt/kvm/ioapic.c') diff --git a/virt/kvm/ioapic.c b/virt/kvm/ioapic.c index dcaf272c26c0..26fd54dc459e 100644 --- a/virt/kvm/ioapic.c +++ b/virt/kvm/ioapic.c @@ -254,13 +254,17 @@ static void __kvm_ioapic_update_eoi(struct kvm_ioapic *ioapic, int vector, } } +bool kvm_ioapic_handles_vector(struct kvm *kvm, int vector) +{ + struct kvm_ioapic *ioapic = kvm->arch.vioapic; + smp_rmb(); + return test_bit(vector, ioapic->handled_vectors); +} + void kvm_ioapic_update_eoi(struct kvm *kvm, int vector, int trigger_mode) { struct kvm_ioapic *ioapic = kvm->arch.vioapic; - smp_rmb(); - if (!test_bit(vector, ioapic->handled_vectors)) - return; spin_lock(&ioapic->lock); __kvm_ioapic_update_eoi(ioapic, vector, trigger_mode); spin_unlock(&ioapic->lock); -- cgit v1.2.3-70-g09d2