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Re: [Qemu-devel] hw/vfio/pci: duplicated invocation of vfio_msix_vector_
From: |
Alex Williamson |
Subject: |
Re: [Qemu-devel] hw/vfio/pci: duplicated invocation of vfio_msix_vector_release() in vfio_msix_disable() |
Date: |
Thu, 12 Sep 2019 15:41:46 +0100 |
On Tue, 10 Sep 2019 19:01:22 +0800
Guoheyi <address@hidden> wrote:
> Hi folks,
>
> Recently we found there are 2 invocations of vfio_msix_vector_release()
> in vfio_msix_disable(). The 1st one is in msix_unset_vector_notifiers(),
> for we set device's msix_vector_release_notifier to
> vfio_msix_vector_release() in vfio_msix_enable(), while the 2nd is the
> explicit one in vfio_msix_disable(). Both invocations switch VFIO to use
> the non-bypass eventfd.
>
> Is there any special reason for doing this? Or can we remove one of them?
The comment certainly suggests there is, and git blame trivially finds:
commit 3e40ba0faf0822fa78336fe6cd9d677ea9b14f1b
Author: Alex Williamson <address@hidden>
Date: Fri Dec 6 11:16:40 2013 -0700
vfio-pci: Release all MSI-X vectors when disabled
We were relying on msix_unset_vector_notifiers() to release all the
vectors when we disable MSI-X, but this only happens when MSI-X is
still enabled on the device. Perform further cleanup by releasing
any remaining vectors listed as in-use after this call. This caused
a leak of IRQ routes on hotplug depending on how the guest OS prepared
the device for removal.
Signed-off-by: Alex Williamson <address@hidden>
Cc: address@hidden
diff --git a/hw/misc/vfio.c b/hw/misc/vfio.c
index f367537737d2..9aecaa82bc34 100644
--- a/hw/misc/vfio.c
+++ b/hw/misc/vfio.c
@@ -905,8 +905,20 @@ static void vfio_disable_msi_common(VFIODevice *vdev)
static void vfio_disable_msix(VFIODevice *vdev)
{
+ int i;
+
msix_unset_vector_notifiers(&vdev->pdev);
+ /*
+ * MSI-X will only release vectors if MSI-X is still enabled on the
+ * device, check through the rest and release it ourselves if necessary.
+ */
+ for (i = 0; i < vdev->nr_vectors; i++) {
+ if (vdev->msi_vectors[i].use) {
+ vfio_msix_vector_release(&vdev->pdev, i);
+ }
+ }
+
if (vdev->nr_vectors) {
vfio_disable_irqindex(vdev, VFIO_PCI_MSIX_IRQ_INDEX);
}