On Fri, Oct 17, 2025 at 10:06:55PM +0000, Wei Liu wrote:
> On Fri, Oct 17, 2025 at 11:58:17AM -0700, Nuno Das Neves wrote:
> > 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. The expectation is that the VMM will retry.
> >
> > However, some VMM code in the wild doesn't do this and simply fails.
> > Rather than force the VMM to retry, change the ioctl to deposit
> > memory on demand and immediately retry the hypercall as is done with
> > all the other hypercall helper functions.
> >
> > In addition to making the ioctl easier to use, removing the need for
> > multiple syscalls improves performance.
> >
> > There is a complication: unlike the other hypercall helper functions,
> > 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.
> >
> > Signed-off-by: Nuno Das Neves <[email protected]>
>
> In v1 you said you will add a "Fixes" tag. Where is it?
I added this:
Fixes: 621191d709b1 ("Drivers: hv: Introduce mshv_root module to expose
/dev/mshv to VMMs")
Let me know if that's not correct.
Wei
