Re: [PATCH v3 13/17] KVM: arm64: Alloc pkvm_hyp_vm using pKVM heap allocator

[Vincent Donnefort <vdonnefort@google.com>]

On Thu, Jul 23, 2026 at 01:14:10PM +0100, Fuad Tabba wrote:
> Hi Vincent,
> 
> On Mon, 20 Jul 2026 at 18:15, Vincent Donnefort <vdonnefort@google.com> wrote:
> ...
> 
> > +static void errno_to_smccc(int ret, struct kvm_cpu_context *host_ctxt)
> > +{
> > +       struct pkvm_hyp_req req = { .type = PKVM_HYP_NO_REQ };
> > +
> > +       switch (ret) {
> > +       case -ENOMEM:
> > +               req.type = PKVM_HYP_REQ_HYP_ALLOC;
> > +               req.mem.nr_pages = hyp_alloc_topup_needed();
> > +               break;
> > +       }
> 
> Sashiko raised this in a different patch. This turns any -ENOMEM into
> a top-up request, but hyp_allocator_map() also returns -ENOMEM from
> the pkvm_map_private_va_range() failure path without setting
> topup_needed, so nr_pages can be 0. The host then handles a 0-page
> top-up and the while (!__ret) loop in pkvm_call_hyp_req() just
> re-issues the same failing hypercall.
> 
> This might not be reachable today, but could you make it so that
> errno_to_smccc() raises the request only when nr_pages is non-zero,
> and let -ENOMEM propagate otherwise?

I could also introduce a HYP_ALLOC specific ENOMEM? 

Otherwise, yes checking on hyp_alloc_topup_needed() sounds alright.

> 
> Cheers,
> /fuad