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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2021-11-14 00:14:05 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-11-14 00:14:05 +0300 |
| commit | ccfff0a2bd2a30de130b5623d242ddecd0272bc2 (patch) | |
| tree | f8350ca2054e1f6350cc4a308d08c60b5fa59a94 | |
| parent | 3ad7befd4842afa2449026715987122a1c6dcb85 (diff) | |
| parent | 61082ad6a6e1f999eef7e7e90046486c87933b1e (diff) | |
| download | linux-ccfff0a2bd2a30de130b5623d242ddecd0272bc2.tar.xz | |
Merge tag 'virtio-mem-for-5.16' of git://github.com/davidhildenbrand/linux
Pull virtio-mem update from David Hildenbrand:
"Support the VIRTIO_MEM_F_UNPLUGGED_INACCESSIBLE feature in virtio-mem,
now that "accidential" access to logically unplugged memory inside
added Linux memory blocks is no longer possible, because we:
- Removed /dev/kmem in commit bbcd53c96071 ("drivers/char: remove
/dev/kmem for good")
- Disallowed access to virtio-mem device memory via /dev/mem in
commit 2128f4e21aa ("virtio-mem: disallow mapping virtio-mem memory
via /dev/mem")
- Sanitized access to virtio-mem device memory via /proc/kcore in
commit 0daa322b8ff9 ("fs/proc/kcore: don't read offline sections,
logically offline pages and hwpoisoned pages")
- Sanitized access to virtio-mem device memory via /proc/vmcore in
commit ce2814622e84 ("virtio-mem: kdump mode to sanitize
/proc/vmcore access")
The new VIRTIO_MEM_F_UNPLUGGED_INACCESSIBLE feature that will be
required by some hypervisors implementing virtio-mem in the near
future, so let's support it now that we safely can"
* tag 'virtio-mem-for-5.16' of git://github.com/davidhildenbrand/linux:
virtio-mem: support VIRTIO_MEM_F_UNPLUGGED_INACCESSIBLE
| -rw-r--r-- | drivers/virtio/virtio_mem.c | 1 | ||||
| -rw-r--r-- | include/uapi/linux/virtio_mem.h | 9 |
2 files changed, 7 insertions, 3 deletions
diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c index 0da0af251c73..96e5a8782769 100644 --- a/drivers/virtio/virtio_mem.c +++ b/drivers/virtio/virtio_mem.c @@ -2889,6 +2889,7 @@ static unsigned int virtio_mem_features[] = { #if defined(CONFIG_NUMA) && defined(CONFIG_ACPI_NUMA) VIRTIO_MEM_F_ACPI_PXM, #endif + VIRTIO_MEM_F_UNPLUGGED_INACCESSIBLE, }; static const struct virtio_device_id virtio_mem_id_table[] = { diff --git a/include/uapi/linux/virtio_mem.h b/include/uapi/linux/virtio_mem.h index 70e01c687d5e..e9122f1d0e0c 100644 --- a/include/uapi/linux/virtio_mem.h +++ b/include/uapi/linux/virtio_mem.h @@ -68,9 +68,10 @@ * explicitly triggered (VIRTIO_MEM_REQ_UNPLUG). * * There are no guarantees what will happen if unplugged memory is - * read/written. Such memory should, in general, not be touched. E.g., - * even writing might succeed, but the values will simply be discarded at - * random points in time. + * read/written. In general, unplugged memory should not be touched, because + * the resulting action is undefined. There is one exception: without + * VIRTIO_MEM_F_UNPLUGGED_INACCESSIBLE, unplugged memory inside the usable + * region can be read, to simplify creation of memory dumps. * * It can happen that the device cannot process a request, because it is * busy. The device driver has to retry later. @@ -87,6 +88,8 @@ /* node_id is an ACPI PXM and is valid */ #define VIRTIO_MEM_F_ACPI_PXM 0 +/* unplugged memory must not be accessed */ +#define VIRTIO_MEM_F_UNPLUGGED_INACCESSIBLE 1 /* --- virtio-mem: guest -> host requests --- */ |