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KVM: x86: Polish exception injection via KVM_SET_GUEST_DEBUG

PATCH Applied Jan Kiszka 2 participants 2 messages Oct 30, 2009 – Nov 3, 2009

Subsystems (3)
x86 KVM KVM x86
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Jan Kiszka

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#0 lore raw

PATCH 1/1 KVM: x86: Polish exception injection via KVM_SET_GUEST_DEBUG

Decouple KVM_GUESTDBG_INJECT_DB and KVM_GUESTDBG_INJECT_BP from KVM_GUESTDBG_ENABLE, their are actually orthogonal. At this chance, avoid triggering the WARN_ON in kvm_queue_exception if there is already an exception pending and reject such invalid requests.

Signed-off-by Jan Kiszka <[email protected]>

---

 arch/x86/kvm/x86.c |   20 ++++++++++++++------
 1 files changed, 14 insertions(+), 6 deletions(-)
arch/x86/kvm/x86.c +14 -6
index 2ef3906..beaa6d4 100644
@@ -4636,10 +4636,20 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
 					struct kvm_guest_debug *dbg)
 {
 	unsigned long rflags;
-	int i;
+	int i, r;
 
 	vcpu_load(vcpu);
 
+	if (dbg->control & (KVM_GUESTDBG_INJECT_DB | KVM_GUESTDBG_INJECT_BP)) {
+		r = -EBUSY;
+		if (vcpu->arch.exception.pending)
+			goto unlock_out;
+		if (dbg->control & KVM_GUESTDBG_INJECT_DB)
+			kvm_queue_exception(vcpu, DB_VECTOR);
+		else
+			kvm_queue_exception(vcpu, BP_VECTOR);
+	}
+
 	/*
 	 * Read rflags as long as potentially injected trace flags are still
 	 * filtered out.

@@ -4675,14 +4685,12 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
 
 	kvm_x86_ops->set_guest_debug(vcpu, dbg);
 
-	if (vcpu->guest_debug & KVM_GUESTDBG_INJECT_DB)
-		kvm_queue_exception(vcpu, DB_VECTOR);
-	else if (vcpu->guest_debug & KVM_GUESTDBG_INJECT_BP)
-		kvm_queue_exception(vcpu, BP_VECTOR);
+	r = 0;
 
+unlock_out:
 	vcpu_put(vcpu);
 
-	return 0;
+	return r;
 }
 
 /*
Applied
#1 lore raw
Quoted 6 lines · Jan Kiszka

Decouple KVM_GUESTDBG_INJECT_DB and KVM_GUESTDBG_INJECT_BP from KVM_GUESTDBG_ENABLE, their are actually orthogonal. At this chance, avoid triggering the WARN_ON in kvm_queue_exception if there is already an exception pending and reject such invalid requests.

Signed-off-by Jan Kiszka <[email protected]>

Applied, thanks.