virtio-mem: remember usable region size

Let's remember the usable region size, which will be helpful in kdump
mode next.

Signed-off-by: David Hildenbrand <[email protected]>
Message-Id: <[email protected]>
Signed-off-by: Michael S. Tsirkin <[email protected]>

Author: davidhildenbrand

drivers/virtio/virtio_mem.c

@@ -133,6 +133,8 @@ struct virtio_mem {
 	uint64_t addr;
 	/* Maximum region size in bytes. */
 	uint64_t region_size;
+	/* Usable region size in bytes. */
+	uint64_t usable_region_size;
 
 	/* The parent resource for all memory added via this device. */
 	struct resource *parent_resource;
@@ -2368,7 +2370,7 @@ static int virtio_mem_cleanup_pending_mb(struct virtio_mem *vm)
 static void virtio_mem_refresh_config(struct virtio_mem *vm)
 {
 	const struct range pluggable_range = mhp_get_pluggable_range(true);
-	uint64_t new_plugged_size, usable_region_size, end_addr;
+	uint64_t new_plugged_size, end_addr;
 
 	/* the plugged_size is just a reflection of what _we_ did previously */
 	virtio_cread_le(vm->vdev, struct virtio_mem_config, plugged_size,
@@ -2378,8 +2380,8 @@ static void virtio_mem_refresh_config(struct virtio_mem *vm)
 
 	/* calculate the last usable memory block id */
 	virtio_cread_le(vm->vdev, struct virtio_mem_config,
-			usable_region_size, &usable_region_size);
-	end_addr = min(vm->addr + usable_region_size - 1,
+			usable_region_size, &vm->usable_region_size);
+	end_addr = min(vm->addr + vm->usable_region_size - 1,
 		       pluggable_range.end);
 
 	if (vm->in_sbm) {
@@ -2763,6 +2765,8 @@ static int virtio_mem_init(struct virtio_mem *vm)
 	virtio_cread_le(vm->vdev, struct virtio_mem_config, addr, &vm->addr);
 	virtio_cread_le(vm->vdev, struct virtio_mem_config, region_size,
 			&vm->region_size);
+	virtio_cread_le(vm->vdev, struct virtio_mem_config, usable_region_size,
+			&vm->usable_region_size);
 
 	/* Determine the nid for the device based on the lowest address. */
 	if (vm->nid == NUMA_NO_NODE)