From f36d4fb85f41604038386e1eb4295acd7d372d86 Mon Sep 17 00:00:00 2001 From: Kunkun Jiang Date: Wed, 27 Oct 2021 17:04:05 +0800 Subject: [PATCH] vfio/pci: Add support for mmapping sub-page MMIO BARs after live migration 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 Reported-by: Qixin Gan Signed-off-by: Kunkun Jiang Link: https://lore.kernel.org/r/20211027090406.761-2-jiangkunkun@huawei.com Signed-off-by: Alex Williamson --- 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)) {