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vfio/pci: Add support for mmapping sub-page MMIO BARs after live migration

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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>
Link: https://lore.kernel.org/r/20211027090406.761-2-jiangkunkun@huawei.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
This commit is contained in:
Kunkun Jiang 2021-10-27 17:04:05 +08:00 committed by Alex Williamson
parent af531756d2
commit f36d4fb85f
1 changed files with 18 additions and 1 deletions
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19
hw/vfio/pci.c
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@ -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)) {