On Fri, Oct 24, 2025 at 05:17:20PM +0800, Xiaoyao Li wrote: > On 10/24/2025 2:59 AM, Peter Xu wrote: > > This name is too generic, and can conflict with in-place guest-memfd > > support. Add a _PRIVATE suffix to show what it really means: it is always > > silently using an internal guest-memfd to back a shared host backend, > > rather than used in-place. > > > > This paves way for in-place guest-memfd, which means we can have a ramblock > > that allocates pages completely from guest-memfd (private or shared). > > It's for patch 4-7. Regarding the rename. How about: > > - RAM_GUEST_MEMFD => RAM_PRIVATE_MEMORY > - backend->guest_memfd => backend->private_memory > - machine_require_guest_memfd() => machine_require_private_memory() > - cgs->require_guest_memfd => cgs->require_private_memory > > For CoCo VMs, what they require is the support of private memory, while the > guest_memfd is how linux provides private memory support. But with mmap > support added to guest memfd, it can serve as shared/non-private memory as > well. Futher, in the future when in-place conversion support is implemented, > a single guest memfd can serve as both shared and private in different > parts. So guest_memfd_private will be confusing at that time.
That's more or less a valid point. Said so, I think PRIVATE_MEMORY is confusing too v.s. RAM_PRIVATE. See: commit 6169f1193657d0ba630a2ce33cef639ae918bce4 Author: Steve Sistare <[email protected]> Date: Wed Jan 15 11:00:31 2025 -0800 memory: add RAM_PRIVATE Not to mention its possible confusion against mmap(MAP_PRIVATE) which is even more well known (where here RAM_PRIVATE is exactly about it). It'll not be a concern until private gmemfd will start to back shared memories, even if it happens (I believe it will, a matter of time..) IMHO it's still fine to use guest_memfd_private, because here private describes that the fd is a private FD (not the memory is private). It's private because it's hidden inside each ramblock that matters. Then a fd that is private can still back shared memories. Would you mind I keep everything as-is for now? Thanks, -- Peter Xu
