Re: [PATCH v4 0/2] KVM: guest_memfd: use write for population

[David Hildenbrand]

On 28.08.25 17:30, Kalyazin, Nikita wrote:
> [ based on kvm/next ]
>
> Implement guest_memfd allocation and population via the write syscall.
> This is useful in non-CoCo use cases where the host can access guest
> memory.  Even though the same can also be achieved via userspace mapping
> and memcpying from userspace, write provides a more performant option
> because it does not need to set page tables and it does not cause a page
> fault for every page like memcpy would.  Note that memcpy cannot be
> accelerated via MADV_POPULATE_WRITE as it is not supported by
> guest_memfd and relies on GUP.

I also added this patch to the pile of guestmemfd preview patches located at

https://git.kernel.org/pub/scm/linux/kernel/git/david/linux.git/log/?h=guestmemfd-preview

There was only one minor conflict regarding setting file->f_mode.

--
Cheers

David / dhildenb