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 <david@redhat.com>
Message-Id: <20241204125444.1734652-11-david@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c
index 126f1d669bb0ef0da9486cec6ac79c45bcb9c430..73477d5b79cff65b825687109818b5733447adc7 100644 (file)
--- a/drivers/virtio/virtio_mem.c
+++ b/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)