Re: [kvm-unit-tests PATCH v3 3/3] s390x: pv: Add test for large host pages backing

["Nico Boehr" <nrb@linux.ibm.com>]

On Fri Dec 20, 2024 at 4:52 PM CET, Claudio Imbrenda wrote:
[...]
> > > diff --git a/s390x/snippets/c/pv-memhog.c b/s390x/snippets/c/pv-memhog.c
> > > new file mode 100644
> > > index 00000000..43f0c2b1
> > > --- /dev/null
> > > +++ b/s390x/snippets/c/pv-memhog.c
> > > @@ -0,0 +1,59 @@  
> > [...]
> > > +int main(void)
> > > +{
> > > +	uint64_t param, addr, i, n;
> > > +
> > > +	READ_ONCE(*MIDPAGE_PTR(SZ_1M + 42 * PAGE_SIZE));
> > > +	param = get_value(42);  
> > 
> > (see below)
> > 
> > > +	n = (param >> 32) & 0x1fffffff;
> > > +	n = n ? n : N_PAGES;
> > > +	param &= 0x7fffffff;
> > > +
> > > +	while (true) {
> > > +		for (i = 0; i < n; i++) {
> > > +			addr = ((param ? i * param : i * i * i) * PAGE_SIZE) & MASK_2G;
> > > +			WRITE_ONCE(*MIDPAGE_PTR(addr), addr);
> > > +		}
> > > +
> > > +		i = get_value(23);
> > > +		if (i != 42)  
> > 
> > I would like some defines for 23 and 42 and possibly share them with the host.
>
> not sure what's the easiest way to share with the host, but I can just
> copy the defines

The sie-dat.c test does this, there's a header file

s390x/snippets/c/sie-dat.h

which is included in the host:

#include "snippets/c/sie-dat.h"

Not the most beautiful way, but works.