On 11/08/2010 01:21 PM, Jan Kiszka wrote:
When we deassign a guest IRQ, clear the potentially asserted guest line.
There might be no chance for the guest to do this, specifically if we
switch from INTx to MSI mode.

Signed-off-by: Jan Kiszka<[email protected]>
---
  virt/kvm/assigned-dev.c |    3 +++
  1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/virt/kvm/assigned-dev.c b/virt/kvm/assigned-dev.c
index 7c98928..ecc4419 100644
--- a/virt/kvm/assigned-dev.c
+++ b/virt/kvm/assigned-dev.c
@@ -141,6 +141,9 @@ static void deassign_guest_irq(struct kvm *kvm,
        kvm_unregister_irq_ack_notifier(kvm,&assigned_dev->ack_notifier);
        assigned_dev->ack_notifier.gsi = -1;

+       kvm_set_irq(assigned_dev->kvm, assigned_dev->irq_source_id,
+                   assigned_dev->guest_irq, 0);
+
        if (assigned_dev->irq_source_id != -1)
                kvm_free_irq_source_id(kvm, assigned_dev->irq_source_id);
        assigned_dev->irq_source_id = -1;

I guess this can't hurt.  Did you see it happen in practice?

Note: all this kvm_set_irq(..., [01]) is incorrect as it doesn't account for polarity. Currently the qemu-emulated chipset uses level high pci interrupts, but that's not a given from kvm's point of view.

I think vfio fixes this by only routing msi interrupts via the kernel, and routing level interrupts through userspace, which can adjust polarity. Alex/Michael?

--
error compiling committee.c: too many arguments to function

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