Gregory Haskins wrote:
> static void kvm_vcpu_irqsink_init(struct kvm_vcpu *vcpu)
> diff --git a/drivers/kvm/svm.c b/drivers/kvm/svm.c
> index a9d917a..c79bfc0 100644
> --- a/drivers/kvm/svm.c
> +++ b/drivers/kvm/svm.c
> @@ -1544,9 +1544,43 @@ static int svm_vcpu_run(struct kvm_vcpu *vcpu, struct
> kvm_run *kvm_run)
> int r;
>
> again:
> + /*
> + * We disable interrupts until the next VMEXIT to eliminate a race
> + * condition for delivery of virtual interrutps. Note that this is
> + * probably not as bad as it sounds, as interrupts will still invoke
> + * a VMEXIT once transitioned to GUEST mode (and thus exit this lock
> + * scope) even if they are disabled.
> + */
> + local_irq_disable();
> +
> spin_lock(&vcpu->irq.lock);
>
> /*
> + * If there are any signals pending (virtual interrupt related or
> + * otherwise), don't even bother trying to enter guest mode...
> + */
> + if (signal_pending(current)) {
> + kvm_run->exit_reason = KVM_EXIT_INTR;
> + spin_unlock(&vcpu->irq.lock);
> + local_irq_enable();
> + r = -EINTR;
> + /*
> + * FIXME: We probably want to move this whole lock-block below
> + * the host->guest state loading so we don't restore when
> + * the system was never saved to begin with
> + */
> + goto out;
> + }
> +
> + /*
> + * There are optimizations we can make when signaling interrupts
> + * if we know the VCPU is in GUEST mode, so record the guest's
> + * CPU to both serve as an indicator of vcpu state and a target
> + * for our interrupts
> + */
> + vcpu->irq.guest_cpu = task_cpu(current);
> +
> + /*
> * We must inject interrupts (if any) while the irq_lock
> * is held
> */
> @@ -1688,6 +1722,15 @@ again:
> #endif
> : "cc", "memory" );
>
> + /*
> + * Signal that we have transitioned back to host mode
> + */
> + spin_lock(&vcpu->irq.lock);
> + vcpu->irq.guest_cpu = -1;
> + spin_unlock(&vcpu->irq.lock);
>
One issue right here. spin_lock() may touch per-cpu data (for
debugging), but %gs has not been restored yet. Moving the block after
host state restore still has problems, though.
> +
> + local_irq_enable();
> +
> if (vcpu->fpu_active) {
> fx_save(vcpu->guest_fx_image);
> fx_restore(vcpu->host_fx_image);
> @@ -1734,20 +1777,23 @@ again:
> if (r > 0) {
> if (signal_pending(current)) {
> ++vcpu->stat.signal_exits;
> - post_kvm_run_save(vcpu, kvm_run);
> kvm_run->exit_reason = KVM_EXIT_INTR;
> - return -EINTR;
> + r = -EINTR;
> + goto out;
> }
>
> if (dm_request_for_irq_injection(vcpu, kvm_run)) {
> ++vcpu->stat.request_irq_exits;
> post_kvm_run_save(vcpu, kvm_run);
> kvm_run->exit_reason = KVM_EXIT_INTR;
> - return -EINTR;
> + r = -EINTR;
> + goto out;
> }
> kvm_resched(vcpu);
> goto again;
> }
> +
> + out:
> post_kvm_run_save(vcpu, kvm_run);
> return r;
> }
>
--
error compiling committee.c: too many arguments to function
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