KVM: x86 emulator: fix in/out emulation.
in/out emulation is broken now. The breakage is different depending
on where IO device resides. If it is in userspace emulator reports
emulation failure since it incorrectly interprets kvm_emulate_pio()
return value. If IO device is in the kernel emulation of 'in' will do
nothing since kvm_emulate_pio() stores result directly into vcpu
registers, so emulator will overwrite result of emulation during
commit of shadowed register.
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 87b3c68..1cceca1c 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2985,22 +2985,20 @@
int size, in, string;
unsigned port;
- ++vcpu->stat.io_exits;
exit_qualification = vmcs_readl(EXIT_QUALIFICATION);
string = (exit_qualification & 16) != 0;
-
- if (string) {
- if (emulate_instruction(vcpu, 0, 0, 0) == EMULATE_DO_MMIO)
- return 0;
- return 1;
- }
-
- size = (exit_qualification & 7) + 1;
in = (exit_qualification & 8) != 0;
- port = exit_qualification >> 16;
+ ++vcpu->stat.io_exits;
+
+ if (string || in)
+ return !(emulate_instruction(vcpu, 0, 0, 0) == EMULATE_DO_MMIO);
+
+ port = exit_qualification >> 16;
+ size = (exit_qualification & 7) + 1;
skip_emulated_instruction(vcpu);
- return kvm_emulate_pio(vcpu, in, size, port);
+
+ return kvm_fast_pio_out(vcpu, size, port);
}
static void
