[PATCH v5 3/4] vfio: add setup_sparse_mmaps hook to VFIODeviceIOOps

[Naman Gulati <namangulati@google.com>]

Add a setup_sparse_mmaps callback to VFIODeviceIOOps so transport
backends (such as vfio-user) can parse custom sparse mmap capabilities,
falling back to vfio_default_setup_sparse_mmaps() to process shared
VFIO mmap capabilities.

Reviewed-by: Thanos Makatos <thanos.makatos@nutanix.com>
Signed-off-by: Naman Gulati <namangulati@google.com>
---
 hw/vfio/vfio-region.h         |  5 +++++
 include/hw/vfio/vfio-device.h | 16 ++++++++++++++++
 hw/vfio/device.c              |  1 +
 hw/vfio/region.c              | 19 ++++++++++++++++---
 4 files changed, 38 insertions(+), 3 deletions(-)

diff --git a/hw/vfio/vfio-region.h b/hw/vfio/vfio-region.h
index 9f6a5cf7d5..a0c9533f9f 100644
--- a/hw/vfio/vfio-region.h
+++ b/hw/vfio/vfio-region.h
@@ -46,4 +46,9 @@ void vfio_region_mmaps_set_enabled(VFIORegion *region, bool enabled);
 void vfio_region_exit(VFIORegion *region);
 void vfio_region_finalize(VFIORegion *region);
 
+struct vfio_region_info;
+int vfio_default_setup_sparse_mmaps(VFIORegion *region,
+                                    struct vfio_region_info *info,
+                                    Error **errp);
+
 #endif /* HW_VFIO_REGION_H */
diff --git a/include/hw/vfio/vfio-device.h b/include/hw/vfio/vfio-device.h
index 8472420d3f..3136e152f2 100644
--- a/include/hw/vfio/vfio-device.h
+++ b/include/hw/vfio/vfio-device.h
@@ -43,6 +43,7 @@ enum {
 
 typedef struct VFIODeviceOps VFIODeviceOps;
 typedef struct VFIODeviceIOOps VFIODeviceIOOps;
+typedef struct VFIORegion VFIORegion;
 typedef struct VFIOMigration VFIOMigration;
 
 typedef struct IOMMUFDBackend IOMMUFDBackend;
@@ -218,6 +219,21 @@ struct VFIODeviceIOOps {
     int (*get_region_info)(VFIODevice *vdev,
                            struct vfio_region_info *info, int *fd);
 
+    /**
+     * @setup_sparse_mmaps
+     *
+     * Parse sparse mmap capabilities for a region and initialize region->mmaps.
+     *
+     * @region: #VFIORegion to set up
+     * @info: region info struct containing capabilities
+     * @errp: pointer to Error*, to store an error if it happens
+     *
+     * Returns 0 on success, -ENODEV if not sparse, or negative error code.
+     */
+    int (*setup_sparse_mmaps)(VFIORegion *region,
+                              struct vfio_region_info *info,
+                              Error **errp);
+
     /**
      * @get_irq_info
      *
diff --git a/hw/vfio/device.c b/hw/vfio/device.c
index 4f11959633..94d6e7ce09 100644
--- a/hw/vfio/device.c
+++ b/hw/vfio/device.c
@@ -662,6 +662,7 @@ static VFIODeviceIOOps vfio_device_io_ops_ioctl = {
 
     .device_feature = vfio_device_io_device_feature,
     .get_region_info = vfio_device_io_get_region_info,
+    .setup_sparse_mmaps = vfio_default_setup_sparse_mmaps,
     .get_irq_info = vfio_device_io_get_irq_info,
     .set_irqs = vfio_device_io_set_irqs,
     .region_read = vfio_device_io_region_read,
diff --git a/hw/vfio/region.c b/hw/vfio/region.c
index 16efed2fce..94cfb708bf 100644
--- a/hw/vfio/region.c
+++ b/hw/vfio/region.c
@@ -162,9 +162,9 @@ static int vfio_mmap_compare_offset(const void *a, const void *b)
     return 0;
 }
 
-static int vfio_setup_region_sparse_mmaps(VFIORegion *region,
-                                          struct vfio_region_info *info,
-                                          Error **errp)
+int vfio_default_setup_sparse_mmaps(VFIORegion *region,
+                                    struct vfio_region_info *info,
+                                    Error **errp)
 {
     struct vfio_info_cap_header *hdr;
     struct vfio_region_info_cap_sparse_mmap *sparse;
@@ -198,6 +198,19 @@ static int vfio_setup_region_sparse_mmaps(VFIORegion *region,
 
     region->nr_mmaps = j;
     region->mmaps = g_realloc(region->mmaps, j * sizeof(VFIOMmap));
+    return 0;
+}
+
+static int vfio_setup_region_sparse_mmaps(VFIORegion *region,
+                                          struct vfio_region_info *info,
+                                          Error **errp)
+{
+    int ret, i;
+
+    ret = region->vbasedev->io_ops->setup_sparse_mmaps(region, info, errp);
+    if (ret) {
+        return ret;
+    }
 
     /*
      * Sort sparse mmaps by offset to ensure proper handling of gaps
-- 
2.56.0.385.gd3acb90ef8-goog