[PATCH 31/35] KVM: x86: Polish exception injection via KVM_SET_GUEST_DEBUG

Avi Kivity
2009-11-19T13:35:07Z

From: Jan Kiszka <jan.kiszka@siemens.com>

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 <jan.kiszka@siemens.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
---
arch/x86/kvm/x86.c | 20 ++++++++++++++------
1 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index cd6fe0a..ba8958d 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4656,10 +4656,20 @@ 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.
@@ -4695,14 +4705,12 @@ 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;
}

/*
--
1.6.5.2