commit 9751377c3a9445f597c5d0bf134a79c8cb58e45d
author Steve Sistare <steven.sistare@oracle.com> Mon Jul 14 12:21:30 2025 -0700
committer Cédric Le Goater <clg@redhat.com> Mon Jul 28 17:52:34 2025 +0200
tree 45edb3c7467fa0b190f7cdd94d7e747141bfeaa6
parent 1dc1220fbd30a200aea972fc3aa53d439aff466b

vfio: fix sub-page bar after cpr

Regions for sub-page BARs are normally mapped here, in response to the
guest writing to PCI config space:

  vfio_pci_write_config()
    pci_default_write_config()
      pci_update_mappings()
        memory_region_add_subregion()
    vfio_sub_page_bar_update_mapping()
      ... vfio_dma_map()

However, after CPR, the guest does not reconfigure the device and the
code path above is not taken.  To fix, in vfio_cpr_pci_post_load, call
vfio_sub_page_bar_update_mapping for each sub-page BAR with a valid
address.

Fixes: 7e9f21411302 ("vfio/container: restore DMA vaddr")

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Link: https://lore.kernel.org/qemu-devel/1752520890-223356-1-git-send-email-steven.sistare@oracle.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

hw/vfio/cpr.c

diff --git a/hw/vfio/cpr.c b/hw/vfio/cpr.c
index af0f12a..384b56c 100644
--- a/hw/vfio/cpr.c
+++ b/hw/vfio/cpr.c
@@ -116,6 +116,8 @@
     PCIDevice *pdev = &vdev->pdev;
     int nr_vectors;
 
+    vfio_sub_page_bar_update_mappings(vdev);
+
     if (msix_enabled(pdev)) {
         vfio_pci_msix_set_notifiers(vdev);
         nr_vectors = vdev->msix->entries;

hw/vfio/pci.c

diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index 0c4606d..f5bc535 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -2824,6 +2824,20 @@
     return ret;
 }
 
+void vfio_sub_page_bar_update_mappings(VFIOPCIDevice *vdev)
+{
+    PCIDevice *pdev = &vdev->pdev;
+    int page_size = qemu_real_host_page_size();
+    int bar;
+
+    for (bar = 0; bar < PCI_ROM_SLOT; bar++) {
+        PCIIORegion *r = &pdev->io_regions[bar];
+        if (r->addr != PCI_BAR_UNMAPPED && r->size > 0 && r->size < page_size) {
+            vfio_sub_page_bar_update_mapping(pdev, bar);
+        }
+    }
+}
+
 static VFIODeviceOps vfio_pci_ops = {
     .vfio_compute_needs_reset = vfio_pci_compute_needs_reset,
     .vfio_hot_reset_multi = vfio_pci_hot_reset_multi,

hw/vfio/pci.h

diff --git a/hw/vfio/pci.h b/hw/vfio/pci.h
index 248e5c4..bca2890 100644
--- a/hw/vfio/pci.h
+++ b/hw/vfio/pci.h
@@ -219,6 +219,7 @@
 uint64_t vfio_vga_read(void *opaque, hwaddr addr, unsigned size);
 void vfio_vga_write(void *opaque, hwaddr addr, uint64_t data, unsigned size);
 
+void vfio_sub_page_bar_update_mappings(VFIOPCIDevice *vdev);
 bool vfio_opt_rom_in_denylist(VFIOPCIDevice *vdev);
 bool vfio_config_quirk_setup(VFIOPCIDevice *vdev, Error **errp);
 void vfio_vga_quirk_setup(VFIOPCIDevice *vdev);