KVM: Skip pio instruction when it is emulated, not executed

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@qumranet.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index 504e81dcbf9000aa0e662e935dc519be4a3d9120..b58fdf37e61776990b8ca333e5b806f8d4c637b0 100644 (file)
--- 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);