We expand MemoryRegions of vfio-pci sub-page MMIO BARs to vfio_pci_write_config to improve IO performance. The MemoryRegions of destination VM will not be expanded successful in live migration, because their addresses have been updated in vmstate_load_state (vfio_pci_load_config).
Remove the restriction on base address change in vfio_pci_write_config for correct mmapping sub-page MMIO BARs. Accroding to my analysis, the remaining parameter verification is enough. Fixes: c5e2fb3ce4d (vfio: Add save and load functions for VFIO PCI devices) Reported-by: Nianyao Tang <[email protected]> Reported-by: Qixin Gan <[email protected]> Signed-off-by: Kunkun Jiang <[email protected]> --- hw/vfio/pci.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-) diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c index e1ea1d8a23..891b211ddf 100644 --- a/hw/vfio/pci.c +++ b/hw/vfio/pci.c @@ -1189,18 +1189,12 @@ void vfio_pci_write_config(PCIDevice *pdev, } } else if (ranges_overlap(addr, len, PCI_BASE_ADDRESS_0, 24) || range_covers_byte(addr, len, PCI_COMMAND)) { - pcibus_t old_addr[PCI_NUM_REGIONS - 1]; int bar; - for (bar = 0; bar < PCI_ROM_SLOT; bar++) { - old_addr[bar] = pdev->io_regions[bar].addr; - } - pci_default_write_config(pdev, addr, val, len); for (bar = 0; bar < PCI_ROM_SLOT; bar++) { - if (old_addr[bar] != pdev->io_regions[bar].addr && - vdev->bars[bar].region.size > 0 && + if (vdev->bars[bar].region.size > 0 && vdev->bars[bar].region.size < qemu_real_host_page_size) { vfio_sub_page_bar_update_mapping(pdev, bar); } -- 2.23.0
