KVM: Do not report TPR write to userspace if new value bigger or equal to a previous one.
Saves many exits to userspace in a case of IRQ chip in userspace.
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 143818e..e283a63 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1862,9 +1862,13 @@
static int cr8_write_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run)
{
+ u8 cr8_prev = kvm_get_cr8(&svm->vcpu);
+ /* instruction emulation calls kvm_set_cr8() */
emulate_instruction(&svm->vcpu, NULL, 0, 0, 0);
if (irqchip_in_kernel(svm->vcpu.kvm))
return 1;
+ if (cr8_prev <= kvm_get_cr8(&svm->vcpu))
+ return 1;
kvm_run->exit_reason = KVM_EXIT_SET_TPR;
return 0;
}
