[01/65] KVM: VMX: fix halt emulation while emulating invalid guest sate

From: Steven Rostedt
Date: Mon Jun 03 2013 - 18:12:06 EST stable review patch.
If anyone has any objections, please let me know.


From: Gleb Natapov <gleb@xxxxxxxxxx>

[ Upstream commit 8d76c49e9ffeee839bc0b7a3278a23f99101263e ]

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 <tomas.papan@xxxxxxxxx>
Tested-by: Tomas Papan <tomas.papan@xxxxxxxxx>
Reviewed-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
CC: stable@xxxxxxxxxxxxxxx
Signed-off-by: Gleb Natapov <gleb@xxxxxxxxxx>
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
arch/x86/kvm/vmx.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index ff66a3b..a0f8dc3 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -5030,6 +5030,12 @@ static int handle_invalid_guest_state(struct kvm_vcpu *vcpu)
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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