From: Nuno Das Neves <[email protected]> Sent: Friday, October 17, 2025 10:26 AM > > On 10/16/2025 6:12 PM, Michael Kelley wrote: > > From: Nuno Das Neves <[email protected]> Sent: Thursday, > > October 16, 2025 12:54 PM > >> > >> When the MSHV_ROOT_HVCALL ioctl is executing a hypercall, and gets > >> HV_STATUS_INSUFFICIENT_MEMORY, it deposits memory and then returns > >> -EAGAIN to userspace. > >> > >> However, it's much easier and efficient if the driver simply deposits > >> memory on demand and immediately retries the hypercall as is done with > >> all the other hypercall helper functions. > >> > >> But unlike those, in MSHV_ROOT_HVCALL the input is opaque to the > >> kernel. This is problematic for rep hypercalls, because the next part > >> of the input list can't be copied on each loop after depositing pages > >> (this was the original reason for returning -EAGAIN in this case). > >> > >> Introduce hv_do_rep_hypercall_ex(), which adds a 'rep_start' > >> parameter. This solves the issue, allowing the deposit loop in > >> MSHV_ROOT_HVCALL to restart a rep hypercall after depositing pages > >> partway through. > > > >>From reading the above, I'm pretty sure this code change is an > > optimization that lets user space avoid having to deal with the > > -EAGAIN result by resubmitting the ioctl with a different > > starting point for a rep hypercall. As such, I'd suggest the patch > > title should be "Improve deposit memory ...." (or something similar). > > The word "Fix" makes it sound like a bug fix. > > > > Or is user space code currently faulty in its handling of -EAGAIN, and > > this really is an indirect bug fix to make things work? If so, do you > > want a Fixes: tag so the change is backported? > > > > It's the latter case, userspace doesn't handle it correctly, so I > consider it a fix more than just an improvement.
OK, thanks. You might want to tweak the commit message a bit to clarify that this really is a bug fix and why. I was leaning toward the wrong conclusion based on the current commit message. Michael > > I'll add a Fixes: tag pointing back to the original /dev/mshv patch. >
