Ackerley Tng via B4 Relay <[email protected]>
writes:
>
> [...snip...]
>
> diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c
> index 69c9d6d546b28..5011d38820d0d 100644
> --- a/virt/kvm/guest_memfd.c
> +++ b/virt/kvm/guest_memfd.c
> @@ -4,6 +4,7 @@
> #include <linux/falloc.h>
> #include <linux/fs.h>
> #include <linux/kvm_host.h>
> +#include <linux/maple_tree.h>
> #include <linux/mempolicy.h>
> #include <linux/pseudo_fs.h>
> #include <linux/pagemap.h>
> @@ -33,6 +34,13 @@ struct gmem_inode {
> struct list_head gmem_file_list;
>
> u64 flags;
> + /*
> + * Every index in this inode, whether memory is populated or
> + * not, is tracked in attributes. The entire range of indices,
> + * corresponding to the size of this inode, is represented in
> + * this maple tree.
Concretely, if the entire guest_memfd is 2M in size, indices [0, 511] is
represented with some value, either 0 (SHARED) or
KVM_MEMORY_ATTRIBUTE_PRIVATE. [512, ULONG_MAX] is also defined in the
tree, as NULL.
Since guest_memfd uses xa_mk_value(0) to store the value 0 ("SHARED"),
that makes 0 distinct from NULL, which works for guest_memfd.
(Liam and I discussed this off-list due to a email configuration issue)
> + */
> + struct maple_tree attributes;
> };
>
>
> [...snip...]
>
