[PATCH v1 3/3] virtio-mem: Add memory with MHP_DRIVER_MANAGED

David Hildenbrand
2020-04-29T16:08:53Z

We don't want /sys/firmware/memmap entries and we want to indicate
our memory as "System RAM (driver managed)" in /proc/iomem. This is
especially relevant for kexec-tools, which have to be updated to
support dumping virtio-mem memory after this patch. Expected behavior in
kexec-tools:
- Don't use this memory when creating a fixed-up firmware memmap. Works
now out of the box on x86-64.
- Don't use this memory for placing kexec segments. Works now out of the
box on x86-64.
- Consider "System RAM (driver managed)" when creating the elfcorehdr
for kdump. This memory has to be dumped. Needs update of kexec-tools.

With this patch on x86-64:

/proc/iomem:
00000000-00000fff : Reserved
00001000-0009fbff : System RAM
[...]
fffc0000-ffffffff : Reserved
100000000-13fffffff : System RAM
140000000-147ffffff : System RAM (driver managed)
340000000-347ffffff : System RAM (driver managed)
348000000-34fffffff : System RAM (driver managed)
[..]
3280000000-32ffffffff : PCI Bus 0000:00

/sys/firmware/memmap:
0000000000000000-000000000009fc00 (System RAM)
000000000009fc00-00000000000a0000 (Reserved)
00000000000f0000-0000000000100000 (Reserved)
0000000000100000-00000000bffe0000 (System RAM)
00000000bffe0000-00000000c0000000 (Reserved)
00000000feffc000-00000000ff000000 (Reserved)
00000000fffc0000-0000000100000000 (Reserved)
0000000100000000-0000000140000000 (System RAM)

Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
drivers/virtio/virtio_mem.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c
index 3101cbf9e59d..6f658d1aeac4 100644
--- a/drivers/virtio/virtio_mem.c
+++ b/drivers/virtio/virtio_mem.c
@@ -421,7 +421,8 @@ static int virtio_mem_mb_add(struct virtio_mem *vm, unsigned long mb_id)
nid = memory_add_physaddr_to_nid(addr);

dev_dbg(&vm->vdev->dev, "adding memory block: %lu\n", mb_id);
- return add_memory(nid, addr, memory_block_size_bytes(), 0);
+ return add_memory(nid, addr, memory_block_size_bytes(),
+ MHP_DRIVER_MANAGED);
}

/*
--
2.25.3