[patch 19/48] KVM: set debug registers after "schedulable" section

[Greg KH]

2.6.27-stable review patch.  If anyone has any objections, please let us know.

------------------
From: Marcelo Tosatti <mtosatti@xxxxxxxxxx>

(cherry picked from commit 29415c37f043d1d54dcf356601d738ff6633b72b)

The vcpu thread can be preempted after the guest_debug_pre() callback,
resulting in invalid debug registers on the new vcpu.

Move it inside the non-preemptable section.

Signed-off-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
Signed-off-by: Avi Kivity <avi@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
---
 arch/x86/kvm/x86.c |    9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2839,10 +2839,6 @@ static int __vcpu_run(struct kvm_vcpu *v
 	down_read(&vcpu->kvm->slots_lock);
 	vapic_enter(vcpu);
 
-preempted:
-	if (vcpu->guest_debug.enabled)
-		kvm_x86_ops->guest_debug_pre(vcpu);
-
 again:
 	if (vcpu->requests)
 		if (test_and_clear_bit(KVM_REQ_MMU_RELOAD, &vcpu->requests))
@@ -2896,6 +2892,9 @@ again:
 		goto out;
 	}
 
+	if (vcpu->guest_debug.enabled)
+		kvm_x86_ops->guest_debug_pre(vcpu);
+
 	vcpu->guest_mode = 1;
 	/*
 	 * Make sure that guest_mode assignment won't happen after
@@ -2970,7 +2969,7 @@ out:
 	if (r > 0) {
 		kvm_resched(vcpu);
 		down_read(&vcpu->kvm->slots_lock);
-		goto preempted;
+		goto again;
 	}
 
 	post_kvm_run_save(vcpu, kvm_run);


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