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vfio: Avoid disabling and enabling vectors repeatedly in VFIO migration

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In VFIO migration resume phase and some guest startups, there are
already unmasked vectors in the vector table when calling
vfio_msix_enable(). So in order to avoid inefficiently disabling
and enabling vectors repeatedly, let's allocate all needed vectors
first and then enable these unmasked vectors one by one without
disabling.

Signed-off-by: Shenming Lu <lushenming@huawei.com>
Message-Id: <20210310030233.1133-4-lushenming@huawei.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
This commit is contained in:
Shenming Lu 2021-03-10 11:02:33 +08:00 committed by Alex Williamson
parent 8ce1ff990e
commit ecebe53fe9
1 changed files with 17 additions and 3 deletions
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20
hw/vfio/pci.c
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@ -569,6 +569,9 @@ static void vfio_msix_vector_release(PCIDevice *pdev, unsigned int nr)
static void vfio_msix_enable(VFIOPCIDevice *vdev)
{
PCIDevice *pdev = &vdev->pdev;
unsigned int nr, max_vec = 0;
vfio_disable_interrupts(vdev);
vdev->msi_vectors = g_new0(VFIOMSIVector, vdev->msix->entries);
@ -587,11 +590,22 @@ static void vfio_msix_enable(VFIOPCIDevice *vdev)
* triggering to userspace, then immediately release the vector, leaving
* the physical device with no vectors enabled, but MSI-X enabled, just
* like the guest view.
* If there are already unmasked vectors (in migration resume phase and
* some guest startups) which will be enabled soon, we can allocate all
* of them here to avoid inefficiently disabling and enabling vectors
* repeatedly later.
*/
vfio_msix_vector_do_use(&vdev->pdev, 0, NULL, NULL);
vfio_msix_vector_release(&vdev->pdev, 0);
if (!pdev->msix_function_masked) {
for (nr = 0; nr < msix_nr_vectors_allocated(pdev); nr++) {
if (!msix_is_masked(pdev, nr)) {
max_vec = nr;
}
}
}
vfio_msix_vector_do_use(pdev, max_vec, NULL, NULL);
vfio_msix_vector_release(pdev, max_vec);
if (msix_set_vector_notifiers(&vdev->pdev, vfio_msix_vector_use,
if (msix_set_vector_notifiers(pdev, vfio_msix_vector_use,
vfio_msix_vector_release, NULL)) {
error_report("vfio: msix_set_vector_notifiers failed");
}