[PATCH 8/11] KVM: Two-way apic tpr synchronization

[Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>]

From: Dor Laor <dor.laor-atKUWr5tajBWk0Htik3J/w@public.gmane.org>

We report the value of cr8 to userspace on an exit.  Also let userspace change
cr8 when we re-enter the guest.  The lets 64-bit guest code maintain the tpr
correctly.

Thanks for Yaniv Kamay for the idea.

Signed-off-by: Dor Laor <dor.laor-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
Signed-off-by: Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>

Index: linux-2.6/drivers/kvm/kvm_main.c
===================================================================
--- linux-2.6.orig/drivers/kvm/kvm_main.c
+++ linux-2.6/drivers/kvm/kvm_main.c
@@ -1360,6 +1360,9 @@ static int kvm_dev_ioctl_run(struct kvm 
 	if (!vcpu)
 		return -ENOENT;
 
+	/* re-sync apic's tpr */
+	vcpu->cr8 = kvm_run->cr8;
+
 	if (kvm_run->emulated) {
 		kvm_arch_ops->skip_emulated_instruction(vcpu);
 		kvm_run->emulated = 0;
Index: linux-2.6/include/linux/kvm.h
===================================================================
--- linux-2.6.orig/include/linux/kvm.h
+++ linux-2.6/include/linux/kvm.h
@@ -65,6 +65,8 @@ struct kvm_run {
 	__u8 ready_for_interrupt_injection;
 	__u8 if_flag;
 	__u16 padding2;
+
+	/* in (pre_kvm_run), out (post_kvm_run) */
 	__u64 cr8;
 	__u64 apic_base;
 

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