[Qemu-devel] [PATCH] memory: size can be different from ptr_size

[Marc-André Lureau]

memory_region_init_ram*_ptr() take only the size of the MemoryRegion,
and allocate a RAMBlock with the same size. However, it may be
convenient to expose a smaller MemoryRegion (for ex: a few bytes) than
the RAMBlock (which must be a multiple of TARGET_PAGE_SIZE).

Signed-off-by: Marc-André Lureau <address@hidden>
---
 include/exec/memory.h  |  8 ++++++--
 exec.c                 |  3 +++
 hw/display/g364fb.c    |  2 +-
 hw/vfio/common.c       |  3 ++-
 hw/virtio/vhost-user.c |  2 +-
 memory.c               | 10 ++++++----
 6 files changed, 19 insertions(+), 9 deletions(-)

diff --git a/include/exec/memory.h b/include/exec/memory.h
index eb4f2fb249..03f257829b 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -700,6 +700,7 @@ void memory_region_init_ram_from_fd(MemoryRegion *mr,
  *        must be unique within any device
  * @size: size of the region.
  * @ptr: memory to be mapped; must contain at least @size bytes.
+ * @ptr_size: size of @ptr buffer
  *
  * Note that this function does not do anything to cause the data in the
  * RAM memory region to be migrated; that is the responsibility of the caller.
@@ -708,7 +709,8 @@ void memory_region_init_ram_ptr(MemoryRegion *mr,
                                 struct Object *owner,
                                 const char *name,
                                 uint64_t size,
-                                void *ptr);
+                                void *ptr,
+                                uint64_t ptr_size);
 
 /**
  * memory_region_init_ram_device_ptr:  Initialize RAM device memory region from
@@ -727,6 +729,7 @@ void memory_region_init_ram_ptr(MemoryRegion *mr,
  * @name: the name of the region.
  * @size: size of the region.
  * @ptr: memory to be mapped; must contain at least @size bytes.
+ * @ptr_size: size of @ptr buffer
  *
  * Note that this function does not do anything to cause the data in the
  * RAM memory region to be migrated; that is the responsibility of the caller.
@@ -736,7 +739,8 @@ void memory_region_init_ram_device_ptr(MemoryRegion *mr,
                                        struct Object *owner,
                                        const char *name,
                                        uint64_t size,
-                                       void *ptr);
+                                       void *ptr,
+                                       uint64_t ptr_size);
 
 /**
  * memory_region_init_alias: Initialize a memory region that aliases all or a
diff --git a/exec.c b/exec.c
index 6826c8337d..fcea614e79 100644
--- a/exec.c
+++ b/exec.c
@@ -2361,6 +2361,9 @@ RAMBlock *qemu_ram_alloc_internal(ram_addr_t size, 
ram_addr_t max_size,
 RAMBlock *qemu_ram_alloc_from_ptr(ram_addr_t size, void *host,
                                    MemoryRegion *mr, Error **errp)
 {
+    assert(size >= TARGET_PAGE_SIZE);
+    assert(size % TARGET_PAGE_SIZE == 0);
+
     return qemu_ram_alloc_internal(size, size, NULL, host, false,
                                    false, mr, errp);
 }
diff --git a/hw/display/g364fb.c b/hw/display/g364fb.c
index fbc2b2422d..f4f5643761 100644
--- a/hw/display/g364fb.c
+++ b/hw/display/g364fb.c
@@ -475,7 +475,7 @@ static void g364fb_init(DeviceState *dev, G364State *s)
 
     memory_region_init_io(&s->mem_ctrl, NULL, &g364fb_ctrl_ops, s, "ctrl", 
0x180000);
     memory_region_init_ram_ptr(&s->mem_vram, NULL, "vram",
-                               s->vram_size, s->vram);
+                               s->vram_size, s->vram, s->vram_size);
     vmstate_register_ram(&s->mem_vram, dev);
     memory_region_set_log(&s->mem_vram, true, DIRTY_MEMORY_VGA);
 }
diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index 7c185e5a2e..e5dfbbafe3 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -854,7 +854,8 @@ int vfio_region_mmap(VFIORegion *region)
         memory_region_init_ram_device_ptr(&region->mmaps[i].mem,
                                           memory_region_owner(region->mem),
                                           name, region->mmaps[i].size,
-                                          region->mmaps[i].mmap);
+                                          region->mmaps[i].mmap,
+                                          region->mmaps[i].size);
         g_free(name);
         memory_region_add_subregion(region->mem, region->mmaps[i].offset,
                                     &region->mmaps[i].mem);
diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index b041343632..3abe960f29 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -935,7 +935,7 @@ static int 
vhost_user_slave_handle_vring_host_notifier(struct vhost_dev *dev,
     name = g_strdup_printf("vhost-user/address@hidden mmaps[%d]",
                            user, queue_idx);
     memory_region_init_ram_device_ptr(&n->mr, OBJECT(vdev), name,
-                                      page_size, addr);
+                                      page_size, addr, page_size);
     g_free(name);
 
     if (virtio_queue_set_host_notifier_mr(vdev, queue_idx, &n->mr, true)) {
diff --git a/memory.c b/memory.c
index 9b73892768..07f8458d38 100644
--- a/memory.c
+++ b/memory.c
@@ -1587,7 +1587,8 @@ void memory_region_init_ram_ptr(MemoryRegion *mr,
                                 Object *owner,
                                 const char *name,
                                 uint64_t size,
-                                void *ptr)
+                                void *ptr,
+                                uint64_t ptr_size)
 {
     memory_region_init(mr, owner, name, size);
     mr->ram = true;
@@ -1597,16 +1598,17 @@ void memory_region_init_ram_ptr(MemoryRegion *mr,
 
     /* qemu_ram_alloc_from_ptr cannot fail with ptr != NULL.  */
     assert(ptr != NULL);
-    mr->ram_block = qemu_ram_alloc_from_ptr(size, ptr, mr, &error_fatal);
+    mr->ram_block = qemu_ram_alloc_from_ptr(ptr_size, ptr, mr, &error_fatal);
 }
 
 void memory_region_init_ram_device_ptr(MemoryRegion *mr,
                                        Object *owner,
                                        const char *name,
                                        uint64_t size,
-                                       void *ptr)
+                                       void *ptr,
+                                       uint64_t ptr_size)
 {
-    memory_region_init_ram_ptr(mr, owner, name, size, ptr);
+    memory_region_init_ram_ptr(mr, owner, name, size, ptr, ptr_size);
     mr->ram_device = true;
     mr->ops = &ram_device_mem_ops;
     mr->opaque = mr;
-- 
2.19.0.rc1