[PATCH v2 1/2] vfio/pci: Fix vfio-pci sub-page MMIO BAR mmaping in live migration

[Kunkun Jiang <jiangkunkun@huawei.com>]

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).

So iterate BARs in vfio_pci_write_config and try to update
sub-page BARs.

Fixes: c5e2fb3ce4d (vfio: Add save and load functions for VFIO PCI devices)
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 | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index e1ea1d8a23..43c7e93153 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 +2468,14 @@ 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++) {
+        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