3.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Gleb Natapov <[email protected]>

commit 8d76c49e9ffeee839bc0b7a3278a23f99101263e upstream.

The invalid guest state emulation loop does not check halt_request
which causes 100% cpu loop while guest is in halt and in invalid
state, but more serious issue is that this leaves halt_request set, so
random instruction emulated by vm86 #GP exit can be interpreted
as halt which causes guest hang. Fix both problems by handling
halt_request in emulation loop.

Reported-by: Tomas Papan <[email protected]>
Tested-by: Tomas Papan <[email protected]>
Reviewed-by: Paolo Bonzini <[email protected]>
Signed-off-by: Gleb Natapov <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

---
 arch/x86/kvm/vmx.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -5197,6 +5197,12 @@ static int handle_invalid_guest_state(st
                        return 0;
                }
 
+               if (vcpu->arch.halt_request) {
+                       vcpu->arch.halt_request = 0;
+                       ret = kvm_emulate_halt(vcpu);
+                       goto out;
+               }
+
                if (signal_pending(current))
                        goto out;
                if (need_resched())


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