vfio/container: pass MemoryRegion to DMA operations

Pass through the MemoryRegion to DMA operation handlers of vfio
containers. The vfio-user container will need this later, to translate
the vaddr into an offset for the dma map vfio-user message; CPR will
also will need this.

Originally-by: John Johnson <john.g.johnson@oracle.com>
Signed-off-by: Jagannathan Raman <jag.raman@oracle.com>
Signed-off-by: Elena Ufimtseva <elena.ufimtseva@oracle.com>
Signed-off-by: John Levon <john.levon@nutanix.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Steve Sistare <steven.sistare@oracle.com>
Link: https://lore.kernel.org/qemu-devel/20250521215534.2688540-1-john.levon@nutanix.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

hw/vfio/container-base.c

@@ -75,12 +75,12 @@ void vfio_address_space_insert(VFIOAddressSpace *space,
 
 int vfio_container_dma_map(VFIOContainerBase *bcontainer,
                            hwaddr iova, ram_addr_t size,
-                           void *vaddr, bool readonly)
+                           void *vaddr, bool readonly, MemoryRegion *mr)
 {
     VFIOIOMMUClass *vioc = VFIO_IOMMU_GET_CLASS(bcontainer);
 
     g_assert(vioc->dma_map);
-    return vioc->dma_map(bcontainer, iova, size, vaddr, readonly);
+    return vioc->dma_map(bcontainer, iova, size, vaddr, readonly, mr);
 }
 
 int vfio_container_dma_unmap(VFIOContainerBase *bcontainer,

hw/vfio/container.c

@@ -207,7 +207,8 @@ static int vfio_legacy_dma_unmap(const VFIOContainerBase *bcontainer,
 }
 
 static int vfio_legacy_dma_map(const VFIOContainerBase *bcontainer, hwaddr iova,
-                               ram_addr_t size, void *vaddr, bool readonly)
+                               ram_addr_t size, void *vaddr, bool readonly,
+                               MemoryRegion *mr)
 {
     const VFIOContainer *container = container_of(bcontainer, VFIOContainer,
                                                   bcontainer);

hw/vfio/iommufd.c

@@ -34,7 +34,8 @@
             TYPE_HOST_IOMMU_DEVICE_IOMMUFD "-vfio"
 
 static int iommufd_cdev_map(const VFIOContainerBase *bcontainer, hwaddr iova,
-                            ram_addr_t size, void *vaddr, bool readonly)
+                            ram_addr_t size, void *vaddr, bool readonly,
+                            MemoryRegion *mr)
 {
     const VFIOIOMMUFDContainer *container =
         container_of(bcontainer, VFIOIOMMUFDContainer, bcontainer);

hw/vfio/listener.c

@@ -170,7 +170,7 @@ static void vfio_iommu_map_notify(IOMMUNotifier *n, IOMMUTLBEntry *iotlb)
          */
         ret = vfio_container_dma_map(bcontainer, iova,
                                      iotlb->addr_mask + 1, vaddr,
-                                     read_only);
+                                     read_only, mr);
         if (ret) {
             error_report("vfio_container_dma_map(%p, 0x%"HWADDR_PRIx", "
                          "0x%"HWADDR_PRIx", %p) = %d (%s)",
@@ -240,7 +240,7 @@ static int vfio_ram_discard_notify_populate(RamDiscardListener *rdl,
         vaddr = memory_region_get_ram_ptr(section->mr) + start;
 
         ret = vfio_container_dma_map(bcontainer, iova, next - start,
-                                     vaddr, section->readonly);
+                                     vaddr, section->readonly, section->mr);
         if (ret) {
             /* Rollback */
             vfio_ram_discard_notify_discard(rdl, section);
@@ -564,7 +564,7 @@ static void vfio_listener_region_add(MemoryListener *listener,
     }
 
     ret = vfio_container_dma_map(bcontainer, iova, int128_get64(llsize),
-                                 vaddr, section->readonly);
+                                 vaddr, section->readonly, section->mr);
     if (ret) {
         error_setg(&err, "vfio_container_dma_map(%p, 0x%"HWADDR_PRIx", "
                    "0x%"HWADDR_PRIx", %p) = %d (%s)",

include/hw/vfio/vfio-container-base.h

@@ -78,7 +78,7 @@ void vfio_address_space_insert(VFIOAddressSpace *space,
 
 int vfio_container_dma_map(VFIOContainerBase *bcontainer,
                            hwaddr iova, ram_addr_t size,
-                           void *vaddr, bool readonly);
+                           void *vaddr, bool readonly, MemoryRegion *mr);
 int vfio_container_dma_unmap(VFIOContainerBase *bcontainer,
                              hwaddr iova, ram_addr_t size,
                              IOMMUTLBEntry *iotlb, bool unmap_all);
@@ -151,20 +151,21 @@ struct VFIOIOMMUClass {
     /**
      * @dma_map
      *
-     * Map an address range into the container.
+     * Map an address range into the container. Note that the memory region is
+     * referenced within an RCU read lock region across this call.
      *
      * @bcontainer: #VFIOContainerBase to use
      * @iova: start address to map
      * @size: size of the range to map
      * @vaddr: process virtual address of mapping
      * @readonly: true if mapping should be readonly
+     * @mr: the memory region for this mapping
      *
      * Returns 0 to indicate success and -errno otherwise.
      */
     int (*dma_map)(const VFIOContainerBase *bcontainer,
                    hwaddr iova, ram_addr_t size,
-                   void *vaddr, bool readonly);
+                   void *vaddr, bool readonly, MemoryRegion *mr);
-
     /**
      * @dma_unmap
      *