linux-kernel - [PATCH 08/10] KVM: Skip pio instruction when it is emulated, not executed

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Message-Id: <11965943273087-git-send-email-avi@qumranet.com>
Date:	Sun,  2 Dec 2007 13:18:45 +0200
From:	Avi Kivity <avi@...ranet.com>
To:	stable@...nel.org
Cc:	linux-kernel@...r.kernel.org, kvm-devel@...ts.sourceforge.net,
	Avi Kivity <avi@...ranet.com>
Subject: [PATCH 08/10] KVM: Skip pio instruction when it is emulated, not executed

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@...ranet.com>
---
 drivers/kvm/kvm_main.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index 504e81d..b58fdf3 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -1757,8 +1757,6 @@ static int complete_pio(struct kvm_vcpu *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, struct kvm_run *run, int in,
 
 	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, struct kvm_run *run, int in,
 	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);
-- 
1.5.3

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