Re: [PATCH v1 1/3] linux-headers: sync VIRTIO_MEM_F_UNPLUGGED_INACCESSIBLE

[Michal Prívozník]

On 11/30/21 10:28, David Hildenbrand wrote:
> TODO: replace by a proper header sync.
> 
> Signed-off-by: David Hildenbrand <david@redhat.com>
> ---
>  include/standard-headers/linux/virtio_mem.h | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/include/standard-headers/linux/virtio_mem.h 
> b/include/standard-headers/linux/virtio_mem.h
> index 05e5ade75d..18c74c527c 100644
> --- a/include/standard-headers/linux/virtio_mem.h
> +++ b/include/standard-headers/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 --- */
> 

This is verbatim copy of kernel commit of 61082ad6a6e1f.

Reviewed-by: Michal Privoznik <mprivozn@redhat.com>

Michal