Re: [PATCH 1/2] vfio: rename field to "num_initial_regions"

[Cédric Le Goater]

On 10/14/25 17:12, John Levon wrote:

We set VFIODevice::num_regions at initialization time, and do not
otherwise refresh it. As it is valid in theory for a VFIO device to
later increase the number of supported regions, rename the field to
"num_initial_regions" to better reflect its semantics.

Signed-off-by: John Levon <john.le...@nutanix.com>

Reviewed-by: Cédric Le Goater <c...@redhat.com>

Thanks,

C.

---
  include/hw/vfio/vfio-device.h |  2 +-
  hw/vfio-user/device.c         |  2 +-
  hw/vfio/ccw.c                 |  4 ++--
  hw/vfio/device.c              | 12 ++++++------
  hw/vfio/iommufd.c             |  3 ++-
  hw/vfio/pci.c                 |  4 ++--
  6 files changed, 14 insertions(+), 13 deletions(-)

diff --git a/include/hw/vfio/vfio-device.h b/include/hw/vfio/vfio-device.h
index 7e9aed6d3c..0fe6c60ba2 100644
--- a/include/hw/vfio/vfio-device.h
+++ b/include/hw/vfio/vfio-device.h
@@ -74,7 +74,7 @@ typedef struct VFIODevice {
      VFIODeviceOps *ops;
      VFIODeviceIOOps *io_ops;
      unsigned int num_irqs;
-    unsigned int num_regions;
+    unsigned int num_initial_regions;
      unsigned int flags;
      VFIOMigration *migration;
      Error *migration_blocker;
diff --git a/hw/vfio-user/device.c b/hw/vfio-user/device.c
index 0609a7dc25..64ef35b320 100644
--- a/hw/vfio-user/device.c
+++ b/hw/vfio-user/device.c
@@ -134,7 +134,7 @@ static int vfio_user_device_io_get_region_info(VFIODevice 
*vbasedev,
      VFIOUserFDs fds = { 0, 1, fd};
      int ret;

- if (info->index > vbasedev->num_regions) {

+    if (info->index > vbasedev->num_initial_regions) {
          return -EINVAL;
      }

diff --git a/hw/vfio/ccw.c b/hw/vfio/ccw.c

index 9560b8d851..4d9588e7aa 100644
--- a/hw/vfio/ccw.c
+++ b/hw/vfio/ccw.c
@@ -484,9 +484,9 @@ static bool vfio_ccw_get_region(VFIOCCWDevice *vcdev, Error 
**errp)
       * We always expect at least the I/O region to be present. We also
       * may have a variable number of regions governed by capabilities.
       */
-    if (vdev->num_regions < VFIO_CCW_CONFIG_REGION_INDEX + 1) {
+    if (vdev->num_initial_regions < VFIO_CCW_CONFIG_REGION_INDEX + 1) {
          error_setg(errp, "vfio: too few regions (%u), expected at least %u",
-                   vdev->num_regions, VFIO_CCW_CONFIG_REGION_INDEX + 1);
+                   vdev->num_initial_regions, VFIO_CCW_CONFIG_REGION_INDEX + 
1);
          return false;
      }

diff --git a/hw/vfio/device.c b/hw/vfio/device.c

index 64f8750389..52079f4cf5 100644
--- a/hw/vfio/device.c
+++ b/hw/vfio/device.c
@@ -257,7 +257,7 @@ int vfio_device_get_region_info_type(VFIODevice *vbasedev, 
uint32_t type,
  {
      int i;

- for (i = 0; i < vbasedev->num_regions; i++) {

+    for (i = 0; i < vbasedev->num_initial_regions; i++) {
          struct vfio_info_cap_header *hdr;
          struct vfio_region_info_cap_type *cap_type;

@@ -466,7 +466,7 @@ void vfio_device_prepare(VFIODevice *vbasedev, VFIOContainer *bcontainer,

      int i;

vbasedev->num_irqs = info->num_irqs;

-    vbasedev->num_regions = info->num_regions;
+    vbasedev->num_initial_regions = info->num_regions;
      vbasedev->flags = info->flags;
      vbasedev->reset_works = !!(info->flags & VFIO_DEVICE_FLAGS_RESET);

@@ -476,10 +476,10 @@ void vfio_device_prepare(VFIODevice *vbasedev, VFIOContainer *bcontainer,

      QLIST_INSERT_HEAD(&vfio_device_list, vbasedev, global_next);

vbasedev->reginfo = g_new0(struct vfio_region_info *,

-                               vbasedev->num_regions);
+                               vbasedev->num_initial_regions);
      if (vbasedev->use_region_fds) {
-        vbasedev->region_fds = g_new0(int, vbasedev->num_regions);
-        for (i = 0; i < vbasedev->num_regions; i++) {
+        vbasedev->region_fds = g_new0(int, vbasedev->num_initial_regions);
+        for (i = 0; i < vbasedev->num_initial_regions; i++) {
              vbasedev->region_fds[i] = -1;
          }
      }
@@ -489,7 +489,7 @@ void vfio_device_unprepare(VFIODevice *vbasedev)
  {
      int i;

- for (i = 0; i < vbasedev->num_regions; i++) {

+    for (i = 0; i < vbasedev->num_initial_regions; i++) {
          g_free(vbasedev->reginfo[i]);
          if (vbasedev->region_fds != NULL && vbasedev->region_fds[i] != -1) {
              close(vbasedev->region_fds[i]);
diff --git a/hw/vfio/iommufd.c b/hw/vfio/iommufd.c
index 68470d552e..10fc065d20 100644
--- a/hw/vfio/iommufd.c
+++ b/hw/vfio/iommufd.c
@@ -663,7 +663,8 @@ found_container:
      vfio_iommufd_cpr_register_device(vbasedev);

trace_iommufd_cdev_device_info(vbasedev->name, devfd, vbasedev->num_irqs,

-                                   vbasedev->num_regions, vbasedev->flags);
+                                   vbasedev->num_initial_regions,
+                                   vbasedev->flags);
      return true;

err_listener_register:

diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index 06b06afc2b..8b8bc5a421 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -2975,9 +2975,9 @@ bool vfio_pci_populate_device(VFIOPCIDevice *vdev, Error 
**errp)
          return false;
      }

- if (vbasedev->num_regions < VFIO_PCI_CONFIG_REGION_INDEX + 1) {

+    if (vbasedev->num_initial_regions < VFIO_PCI_CONFIG_REGION_INDEX + 1) {
          error_setg(errp, "unexpected number of io regions %u",
-                   vbasedev->num_regions);
+                   vbasedev->num_initial_regions);
          return false;
      }