Hi Will,
On Mon, Jul 17, 2023 at 12:03 PM Will Deacon <will@xxxxxxxxxx> wrote:
>
> On Mon, Jul 17, 2023 at 11:23:00AM +0100, Fuad Tabba wrote:
> > If host_ram_size() * RAM_SIZE_RATIO does not result in a value
> > aligned to the host page size, it triggers an error in
> > __kvm_set_memory_region(), called via the
> > KVM_SET_USER_MEMORY_REGION ioctl, which requires the size to be
> > page-aligned.
> >
> > Fixes: 18bd8c3bd2a7 ("kvm tools: Don't use all of host RAM for guests by default")
> > Signed-off-by: Fuad Tabba <tabba@xxxxxxxxxx>
> > ---
> > builtin-run.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/builtin-run.c b/builtin-run.c
> > index 2801735..ff8ba0b 100644
> > --- a/builtin-run.c
> > +++ b/builtin-run.c
> > @@ -406,7 +406,7 @@ static u64 get_ram_size(int nr_cpus)
> > if (ram_size > available)
> > ram_size = available;
> >
> > - return ram_size;
> > + return ALIGN(ram_size, host_page_size());
> > }
>
> I guess we could avoid querying the page size twice if we also factored
> out a helper to grab _SC_PHYS_PAGES and then did the multiply by
> RAM_SIZE_RATIO before converting back to bytes.
>
> e.g. something like:
>
> available = MIN_RAM_SIZE;
>
> nrpages = host_ram_nrpages() * RAM_SIZE_RATIO;
> if (nrpages)
> available = nrpages * host_page_size();
>
> and then host_ram_size() just calls the two new helpers.
>
> What do you think?
Sounds good to me. I'll respin.
Cheers,
/fuad
>
> Will
