[PATCH 07/27] vfio: add per-region fd support

[John Levon <john.levon@nutanix.com>]

For vfio-user, each region has its own fd rather than sharing
vbasedev's. Add the necessary plumbing to support this. For vfio
backends with a shared fd, initialize region->fd to the shared one.

Signed-off-by: John Levon <john.levon@nutanix.com>
---
 include/hw/vfio/vfio-device.h |  7 +++++--
 include/hw/vfio/vfio-region.h |  1 +
 hw/vfio/device.c              | 28 ++++++++++++++++++++++++++--
 hw/vfio/region.c              |  7 ++++++-
 4 files changed, 38 insertions(+), 5 deletions(-)

diff --git a/include/hw/vfio/vfio-device.h b/include/hw/vfio/vfio-device.h
index 923f9cd116..5cb817fd6a 100644
--- a/include/hw/vfio/vfio-device.h
+++ b/include/hw/vfio/vfio-device.h
@@ -66,6 +66,7 @@ typedef struct VFIODevice {
     OnOffAuto enable_migration;
     OnOffAuto migration_multifd_transfer;
     bool migration_events;
+    bool use_region_fds;
     VFIODeviceOps *ops;
     VFIODeviceIOOps *io_ops;
     unsigned int num_irqs;
@@ -84,6 +85,7 @@ typedef struct VFIODevice {
     VFIOIOASHwpt *hwpt;
     QLIST_ENTRY(VFIODevice) hwpt_next;
     struct vfio_region_info **reginfo;
+    int *region_fds;
 } VFIODevice;
 
 struct VFIODeviceOps {
@@ -172,10 +174,11 @@ struct VFIODeviceIOOps {
     /**
      * @get_region_info
      *
-     * Fill in @info with information on the region given by @info->index.
+     * Fill in @info (and optionally @fd) with information on the region given
+     * by @info->index.
      */
     int (*get_region_info)(VFIODevice *vdev,
-                           struct vfio_region_info *info);
+                           struct vfio_region_info *info, int *fd);
 
     /**
      * @get_irq_info
diff --git a/include/hw/vfio/vfio-region.h b/include/hw/vfio/vfio-region.h
index cbffb26962..80e83b23fd 100644
--- a/include/hw/vfio/vfio-region.h
+++ b/include/hw/vfio/vfio-region.h
@@ -29,6 +29,7 @@ typedef struct VFIORegion {
     uint32_t nr_mmaps;
     VFIOMmap *mmaps;
     uint8_t nr; /* cache the region number for debug */
+    int fd; /* fd to mmap() region */
 } VFIORegion;
 
 
diff --git a/hw/vfio/device.c b/hw/vfio/device.c
index d0068086ae..41db403992 100644
--- a/hw/vfio/device.c
+++ b/hw/vfio/device.c
@@ -226,6 +226,7 @@ int vfio_device_get_region_info(VFIODevice *vbasedev, int index,
                                 struct vfio_region_info **info)
 {
     size_t argsz = sizeof(struct vfio_region_info);
+    int fd = -1;
     int ret;
 
     /* check cache */
@@ -240,7 +241,7 @@ int vfio_device_get_region_info(VFIODevice *vbasedev, int index,
 retry:
     (*info)->argsz = argsz;
 
-    ret = vbasedev->io_ops->get_region_info(vbasedev, *info);
+    ret = vbasedev->io_ops->get_region_info(vbasedev, *info, &fd);
     if (ret != 0) {
         g_free(*info);
         *info = NULL;
@@ -251,11 +252,19 @@ retry:
         argsz = (*info)->argsz;
         *info = g_realloc(*info, argsz);
 
+        if (fd != -1) {
+            close(fd);
+            fd = -1;
+        }
+
         goto retry;
     }
 
     /* fill cache */
     vbasedev->reginfo[index] = *info;
+    if (vbasedev->region_fds != NULL) {
+        vbasedev->region_fds[index] = fd;
+    }
 
     return 0;
 }
@@ -360,6 +369,7 @@ void vfio_device_init(VFIODevice *vbasedev, int type, VFIODeviceOps *ops,
     vbasedev->io_ops = &vfio_device_io_ops_ioctl;
     vbasedev->dev = dev;
     vbasedev->fd = -1;
+    vbasedev->use_region_fds = false;
 
     vbasedev->ram_block_discard_allowed = ram_discard;
 }
@@ -470,6 +480,9 @@ void vfio_device_prepare(VFIODevice *vbasedev, VFIOContainerBase *bcontainer,
 
     vbasedev->reginfo = g_new0(struct vfio_region_info *,
                                vbasedev->num_regions);
+    if (vbasedev->use_region_fds) {
+        vbasedev->region_fds = g_new0(int, vbasedev->num_regions);
+    }
 }
 
 void vfio_device_unprepare(VFIODevice *vbasedev)
@@ -478,9 +491,17 @@ void vfio_device_unprepare(VFIODevice *vbasedev)
 
     for (i = 0; i < vbasedev->num_regions; i++) {
         g_free(vbasedev->reginfo[i]);
+        if (vbasedev->region_fds != NULL && vbasedev->region_fds[i] != -1) {
+            close(vbasedev->region_fds[i]);
+        }
+
     }
     g_free(vbasedev->reginfo);
     vbasedev->reginfo = NULL;
+    if (vbasedev->region_fds != NULL) {
+        g_free(vbasedev->region_fds);
+        vbasedev->region_fds = NULL;
+    }
 
     QLIST_REMOVE(vbasedev, container_next);
     QLIST_REMOVE(vbasedev, global_next);
@@ -502,10 +523,13 @@ static int vfio_device_io_device_feature(VFIODevice *vbasedev,
 }
 
 static int vfio_device_io_get_region_info(VFIODevice *vbasedev,
-                                          struct vfio_region_info *info)
+                                          struct vfio_region_info *info,
+                                          int *fd)
 {
     int ret;
 
+    *fd = -1;
+
     ret = ioctl(vbasedev->fd, VFIO_DEVICE_GET_REGION_INFO, info);
 
     return ret < 0 ? -errno : ret;
diff --git a/hw/vfio/region.c b/hw/vfio/region.c
index 34752c3f65..3c93da91d8 100644
--- a/hw/vfio/region.c
+++ b/hw/vfio/region.c
@@ -200,6 +200,11 @@ int vfio_region_setup(Object *obj, VFIODevice *vbasedev, VFIORegion *region,
     region->size = info->size;
     region->fd_offset = info->offset;
     region->nr = index;
+    if (vbasedev->region_fds != NULL) {
+        region->fd = vbasedev->region_fds[index];
+    } else {
+        region->fd = vbasedev->fd;
+    }
 
     if (region->size) {
         region->mem = g_new0(MemoryRegion, 1);
@@ -278,7 +283,7 @@ int vfio_region_mmap(VFIORegion *region)
 
         region->mmaps[i].mmap = mmap(map_align, region->mmaps[i].size, prot,
                                      MAP_SHARED | MAP_FIXED,
-                                     region->vbasedev->fd,
+                                     region->fd,
                                      region->fd_offset +
                                      region->mmaps[i].offset);
         if (region->mmaps[i].mmap == MAP_FAILED) {
-- 
2.43.0