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 75ac4c58bc0d ("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" <m...@redhat.com>
Cc: Pankaj Gupta <pankaj.gupta.li...@gmail.com>
Cc: teawater <teawat...@linux.alibaba.com>
Signed-off-by: David Hildenbrand <da...@redhat.com>
---
Based on latest Linus' tree (and not a tag) because
- virtio-mem has just been merged via the vhost tree
- add_memory_driver_managed() has been merged a week ago via the -mm tree
I'd like to have this patch in 5.8, with the initial merge of virtio-mem
if possible (so the user space representation of virtio-mem added memory
resources won't change anymore).
---
drivers/virtio/virtio_mem.c | 25 ++++++++++++++++++++++---
1 file changed, 22 insertions(+), 3 deletions(-)
diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c
index 50c689f250450..d2eab3558a9e1 100644
--- a/drivers/virtio/virtio_mem.c
+++ b/drivers/virtio/virtio_mem.c
@@ -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);
--
2.26.2
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