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virtio-mem: add memory via add_memory_driver_managed() 

Virtio-mem managed memory is always detected and added by the virtio-mem
driver, never using something like the firmware-provided memory map.
This is the case after an ordinary system reboot, and has to be guaranteed
after kexec. Especially, virtio-mem added memory resources can contain
inaccessible parts ("unblocked memory blocks"), blindly forwarding them
to a kexec kernel is dangerous, as unplugged memory will get accessed
(esp. written).

Let's use the new way of adding special driver-managed memory introduced
in commit 7b7b27214b ("mm/memory_hotplug: introduce
add_memory_driver_managed()").

This will result in no entries in /sys/firmware/memmap ("raw firmware-
provided memory map"), the memory resource will be flagged
IORESOURCE_MEM_DRIVER_MANAGED (esp., kexec_file_load() will not place
kexec images on this memory), and it is exposed as "System RAM
(virtio_mem)" in /proc/iomem, so esp. kexec-tools can properly handle it.

Example /proc/iomem before this change:
  [...]
  140000000-333ffffff : virtio0
    140000000-147ffffff : System RAM
  334000000-533ffffff : virtio1
    338000000-33fffffff : System RAM
    340000000-347ffffff : System RAM
    348000000-34fffffff : System RAM
  [...]

Example /proc/iomem after this change:
  [...]
  140000000-333ffffff : virtio0
    140000000-147ffffff : System RAM (virtio_mem)
  334000000-533ffffff : virtio1
    338000000-33fffffff : System RAM (virtio_mem)
    340000000-347ffffff : System RAM (virtio_mem)
    348000000-34fffffff : System RAM (virtio_mem)
  [...]

Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: teawater <teawaterz@linux.alibaba.com>
Fixes: 5f1f79bbc9 ("virtio-mem: Paravirtualized memory hotplug")
Signed-off-by: David Hildenbrand <david@redhat.com>
Link: https://lore.kernel.org/r/20200611093518.5737-1-david@redhat.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
This commit is contained in:
David Hildenbrand 2020-06-11 11:35:18 +02:00 committed by Michael S. Tsirkin
parent 1c3d69ab53
commit b3562c6087
1 changed files with 22 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

25
drivers/virtio/virtio_mem.c
View File

@ -101,6 +101,11 @@ struct virtio_mem {
/* The parent resource for all memory added via this device. */
struct resource *parent_resource;
/*
* Copy of "System RAM (virtio_mem)" to be used for
* add_memory_driver_managed().
*/
const char *resource_name;
/* Summary of all memory block states. */
unsigned long nb_mb_state[VIRTIO_MEM_MB_STATE_COUNT];
@ -414,8 +419,20 @@ static int virtio_mem_mb_add(struct virtio_mem *vm, unsigned long mb_id)
if (nid == NUMA_NO_NODE)
nid = memory_add_physaddr_to_nid(addr);
/*
* When force-unloading the driver and we still have memory added to
* Linux, the resource name has to stay.
*/
if (!vm->resource_name) {
vm->resource_name = kstrdup_const("System RAM (virtio_mem)",
GFP_KERNEL);
if (!vm->resource_name)
return -ENOMEM;
}
dev_dbg(&vm->vdev->dev, "adding memory block: %lu\n", mb_id);
return add_memory(nid, addr, memory_block_size_bytes());
return add_memory_driver_managed(nid, addr, memory_block_size_bytes(),
vm->resource_name);
}
/*
@ -1890,10 +1907,12 @@ static void virtio_mem_remove(struct virtio_device *vdev)
vm->nb_mb_state[VIRTIO_MEM_MB_STATE_OFFLINE_PARTIAL] ||
vm->nb_mb_state[VIRTIO_MEM_MB_STATE_ONLINE] ||
vm->nb_mb_state[VIRTIO_MEM_MB_STATE_ONLINE_PARTIAL] ||
vm->nb_mb_state[VIRTIO_MEM_MB_STATE_ONLINE_MOVABLE])
vm->nb_mb_state[VIRTIO_MEM_MB_STATE_ONLINE_MOVABLE]) {
dev_warn(&vdev->dev, "device still has system memory added\n");
else
} else {
virtio_mem_delete_resource(vm);
kfree_const(vm->resource_name);
}
/* remove all tracking data - no locking needed */
vfree(vm->mb_state);