linux/drivers/virtio
David Hildenbrand b3562c6087 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>
2020-06-22 12:34:21 -04:00
..
Kconfig treewide: replace '---help---' in Kconfig files with 'help' 2020-06-14 01:57:21 +09:00
Makefile virtio-mem: Paravirtualized memory hotplug 2020-06-04 15:36:52 -04:00
virtio.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
virtio_balloon.c virtio-balloon: Disable free page reporting if page poison reporting is not enabled 2020-06-04 15:36:51 -04:00
virtio_input.c virtio_input: pull in slab.h 2020-04-17 06:05:29 -04:00
virtio_mem.c virtio-mem: add memory via add_memory_driver_managed() 2020-06-22 12:34:21 -04:00
virtio_mmio.c virtio-mmio: Delete an error message in vm_find_vqs() 2020-06-02 02:45:13 -04:00
virtio_pci_common.c virtio-pci: check name when counting MSI-X vectors 2020-02-06 03:40:26 -05:00
virtio_pci_common.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 78 2019-05-24 17:37:51 +02:00
virtio_pci_legacy.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 78 2019-05-24 17:37:51 +02:00
virtio_pci_modern.c virtio: add VIRTIO_RING_NO_LEGACY 2020-06-02 02:45:13 -04:00
virtio_ring.c virtio_ring: Fix mem leak with vring_new_virtqueue() 2020-03-08 05:35:23 -04:00
virtio_vdpa.c virtio: introduce a vDPA based transport 2020-04-01 12:06:26 -04:00