packages/qemu
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

vfio: Avoid disabling and enabling vectors repeatedly in VFIO migration

Browse Source 
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:
Chen Qun 2021-03-10 11:02:33 +08:00
parent fa9e2da774
commit 66cf77a224
1 changed files with 63 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

63
vfio-Avoid-disabling-and-enabling-vectors-repeatedly.patch Normal file
View File

@ -0,0 +1,63 @@
From 8113fdcf0c1383ae5b9542563656bea3753d834e Mon Sep 17 00:00:00 2001
From: Shenming Lu <lushenming@huawei.com>
Date: Wed, 10 Mar 2021 11:02:33 +0800
Subject: [PATCH] vfio: Avoid disabling and enabling vectors repeatedly in VFIO
migration
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>
---
hw/vfio/pci.c | 20 +++++++++++++++++---
1 file changed, 17 insertions(+), 3 deletions(-)
diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index a637c35e7a..da7c740bce 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -563,6 +563,9 @@ 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);
@@ -581,11 +584,22 @@ 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");
}
--
2.27.0