[patch 24/60] KVM: Skip pio instruction when it is emulated, not executed

[Greg KH <gregkh-l3A5Bk7waGM@public.gmane.org>]

[-- Attachment #1: kvm-skip-pio-instruction-when-it-is-emulated-not-executed.patch --]
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2.6.23-stable review patch.  If anyone has any objections, please let us
know.

------------------
From: Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>

patch 0967b7bf1c22b55777aba46ff616547feed0b141 in mainline.

If we defer updating rip until pio instructions are executed, we have a
problem with reset:  a pio reset updates rip, and when the instruction
completes we skip the emulated instruction, pointing rip somewhere completely
unrelated.

Fix by updating rip when we see decode the instruction, not after emulation.

Signed-off-by: Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
Signed-off-by: Greg Kroah-Hartman <gregkh-l3A5Bk7waGM@public.gmane.org>

---
 drivers/kvm/kvm_main.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -1757,8 +1757,6 @@ static int complete_pio(struct kvm_vcpu 
 	io->count -= io->cur_count;
 	io->cur_count = 0;
 
-	if (!io->count)
-		kvm_arch_ops->skip_emulated_instruction(vcpu);
 	return 0;
 }
 
@@ -1804,6 +1802,7 @@ int kvm_setup_pio(struct kvm_vcpu *vcpu,
 
 	pio_dev = vcpu_find_pio_dev(vcpu, port);
 	if (!string) {
+		kvm_arch_ops->skip_emulated_instruction(vcpu);
 		kvm_arch_ops->cache_regs(vcpu);
 		memcpy(vcpu->pio_data, &vcpu->regs[VCPU_REGS_RAX], 4);
 		kvm_arch_ops->decache_regs(vcpu);
@@ -1850,6 +1849,9 @@ int kvm_setup_pio(struct kvm_vcpu *vcpu,
 	vcpu->run->io.count = now;
 	vcpu->pio.cur_count = now;
 
+	if (now == count)
+		kvm_arch_ops->skip_emulated_instruction(vcpu);
+
 	for (i = 0; i < nr_pages; ++i) {
 		spin_lock(&vcpu->kvm->lock);
 		page = gva_to_page(vcpu, address + i * PAGE_SIZE);

-- 

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