Re: [RFC PATCH 8/8] kvm: gmem: Allow restricted userspace mappings

David Hildenbrand
2024-07-09T21:13:32Z

On 09.07.24 16:48, Fuad Tabba wrote:
> Hi Patrick,
>
> On Tue, Jul 9, 2024 at 2:21 PM Patrick Roy <roypat@amazon.co.uk> wrote:
>>
>> Allow mapping guest_memfd into userspace. Since AS_INACCESSIBLE is set
>> on the underlying address_space struct, no GUP of guest_memfd will be
>> possible.
>
> This patch allows mapping guest_memfd() unconditionally. Even if it's
> not guppable, there are other reasons why you wouldn't want to allow
> this. Maybe a config flag to gate it? e.g.,

As discussed with Jason, maybe not the direction we want to take with
guest_memfd.
If it's private memory, it shall not be mapped. Also not via magic
config options.

We'll likely discuss some of that in the meeting MM tomorrow I guess
(having both shared and private memory in guest_memfd).

Note that just from staring at this commit, I don't understand the
motivation *why* we would want to do that.

--
Cheers,

David / dhildenb