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[PATCH v3 1/2] vfio/pci: Add support for mmapping sub-page MMIO BARs aft
From: |
Kunkun Jiang |
Subject: |
[PATCH v3 1/2] vfio/pci: Add support for mmapping sub-page MMIO BARs after live migration |
Date: |
Wed, 27 Oct 2021 17:04:05 +0800 |
We can expand MemoryRegions of sub-page MMIO BARs in
vfio_pci_write_config() to improve IO performance for some
devices. However, the MemoryRegions of destination VM are
not expanded any more after live migration. Because their
addresses have been updated in vmstate_load_state()
(vfio_pci_load_config) and vfio_sub_page_bar_update_mapping()
will not be called.
This may result in poor performance after live migration.
So iterate BARs in vfio_pci_load_config() and try to update
sub-page BARs.
Reported-by: Nianyao Tang <tangnianyao@huawei.com>
Reported-by: Qixin Gan <ganqixin@huawei.com>
Signed-off-by: Kunkun Jiang <jiangkunkun@huawei.com>
---
hw/vfio/pci.c | 19 ++++++++++++++++++-
1 file changed, 18 insertions(+), 1 deletion(-)
diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index 5cdf1d4298..7b45353ce2 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -2453,7 +2453,12 @@ static int vfio_pci_load_config(VFIODevice *vbasedev,
QEMUFile *f)
{
VFIOPCIDevice *vdev = container_of(vbasedev, VFIOPCIDevice, vbasedev);
PCIDevice *pdev = &vdev->pdev;
- int ret;
+ pcibus_t old_addr[PCI_NUM_REGIONS - 1];
+ int bar, ret;
+
+ for (bar = 0; bar < PCI_ROM_SLOT; bar++) {
+ old_addr[bar] = pdev->io_regions[bar].addr;
+ }
ret = vmstate_load_state(f, &vmstate_vfio_pci_config, vdev, 1);
if (ret) {
@@ -2463,6 +2468,18 @@ static int vfio_pci_load_config(VFIODevice *vbasedev,
QEMUFile *f)
vfio_pci_write_config(pdev, PCI_COMMAND,
pci_get_word(pdev->config + PCI_COMMAND), 2);
+ for (bar = 0; bar < PCI_ROM_SLOT; bar++) {
+ /*
+ * The address may not be changed in some scenarios
+ * (e.g. the VF driver isn't loaded in VM).
+ */
+ if (old_addr[bar] != pdev->io_regions[bar].addr &&
+ vdev->bars[bar].region.size > 0 &&
+ vdev->bars[bar].region.size < qemu_real_host_page_size) {
+ vfio_sub_page_bar_update_mapping(pdev, bar);
+ }
+ }
+
if (msi_enabled(pdev)) {
vfio_msi_enable(vdev);
} else if (msix_enabled(pdev)) {
--
2.23.0