On Wed, 30 Jul 2025 16:56:18 -0400 Peter Xu <peterx@xxxxxxxxxx> wrote: > On Fri, Jul 25, 2025 at 11:54:27AM +0200, Igor Mammedov wrote: > > If number of CPUs is increased up to 2048, it will push > > available pages above 16Mb range and make smap/pku/pks > > tests fail with 'Could not reserve memory' error. > > > > Move pages used by tests to 32Mb to fix it. > > > > Signed-off-by: Igor Mammedov <imammedo@xxxxxxxxxx> > > Reviewed-by: Peter Xu <peterx@xxxxxxxxxx> > > > --- > > x86/pks.c | 2 +- > > x86/pku.c | 2 +- > > x86/smap.c | 2 +- > > 3 files changed, 3 insertions(+), 3 deletions(-) > > > > diff --git a/x86/pks.c b/x86/pks.c > > index f4d6ac83..9b9519ba 100644 > > --- a/x86/pks.c > > +++ b/x86/pks.c > > @@ -6,7 +6,7 @@ > > #include "x86/msr.h" > > > > #define PTE_PKEY_BIT 59 > > -#define SUPER_BASE (1 << 23) > > +#define SUPER_BASE (2 << 24) > > Nitpick: maybe 1<<25 would be easier to read. I can try with, if I have to respin. > Below are some random thoughts when reading these tests.. > > I'm not sure whether I understand them correctly here: all of them so far > depend on the "test" var present in the .bss section, and they all assumed > that the var's physical address (likely together with the whole .bss) will > be under SUPER_BASE after loaded in the VM. > > Based on that, there's yet another restriction versus the need to reserve > (SUPER_BASE, SUPER_BASE*2), because the tests want to map the same (0, > SUPER_BASE) memory twice in that virtual address range, so here the tests > do not really need the phys pages in the back but kind of a way to reserve > virtual addresses.. > > Instead of these tricks, I wonder whether we can do alloc_page() once, then > put the test var on the page allocated. Then we can build the required > PKU/PKS/SMAP special pgtables on top, mapping to the page allocated. It > should make sure system changes (like growing num_cpus) never affect it > anymore. > > That (even if feasible.. or maybe I missed something) can definitely > involve more changes, so not something to ask for on adding the hpet test / > x2apic support. Just some pure thoughts when reading it.. I had the same thoughts but I'm not confident enough to rewrite those tests. Hence a knee-jerk reaction of just fixing up base to unbreak affected test. > > Thanks, >
