Re: kvm/queue demand paging test and s390

[Andrew Jones <drjones@xxxxxxxxxx>]

On Tue, Mar 10, 2020 at 05:54:59PM +0100, Christian Borntraeger wrote:
> For s390 the guest memory size must be 1M aligned. I need something like the following to make this work:
> 
> diff --git a/tools/testing/selftests/kvm/demand_paging_test.c b/tools/testing/selftests/kvm/demand_paging_test.c
> index c1e326d3ed7f..f85ec3f01a35 100644
> --- a/tools/testing/selftests/kvm/demand_paging_test.c
> +++ b/tools/testing/selftests/kvm/demand_paging_test.c
> @@ -164,6 +164,10 @@ static struct kvm_vm *create_vm(enum vm_guest_mode mode, int vcpus,
>         pages += ((2 * vcpus * vcpu_memory_bytes) >> PAGE_SHIFT_4K) /
>                  PTES_PER_4K_PT;
>         pages = vm_adjust_num_guest_pages(mode, pages);
> +#ifdef __s390x__
> +       /* s390 requires 1M aligned guest sizes */
> +       pages = (pages + 255) & ~0xff;
> +#endif
>  
>         pr_info("Testing guest mode: %s\n", vm_guest_mode_string(mode));
>  
> 
> any better idea how to do that?
>

For this one we could patch[*] vm_adjust_num_guest_pages(). That would
also allow the one on line 382, and another one at dirty_log_test.c:300
to be hidden.

I'd also like to add a

 unsigned int vm_calc_num_guest_pages(enum vm_guest_mode mode, size_t size)
 {
      unsigned int n;
      n = DIV_ROUND_UP(size, vm_guest_mode_params[mode].page_size);
      return vm_adjust_num_guest_pages(mode, n);
 }

to the num-pages API we've recently put in kvm/queue. If we do, then we
could add a #ifdef-390x to that as well.

Thanks,
drew


[*]

diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
index fc84da4b72d4..9569b21eed26 100644
--- a/tools/testing/selftests/kvm/include/kvm_util.h
+++ b/tools/testing/selftests/kvm/include/kvm_util.h
@@ -261,7 +261,13 @@ unsigned int vm_num_guest_pages(enum vm_guest_mode mode, unsigned int num_host_p
 static inline unsigned int
 vm_adjust_num_guest_pages(enum vm_guest_mode mode, unsigned int num_guest_pages)
 {
-       return vm_num_guest_pages(mode, vm_num_host_pages(mode, num_guest_pages));
+       unsigned int n;
+       n = vm_num_guest_pages(mode, vm_num_host_pages(mode, num_guest_pages));
+#ifdef __s390x__
+       /* s390 requires 1M aligned guest sizes */
+       n = (n + 255) & ~0xff;
+#endif
+       return n;
 }
 
 struct kvm_userspace_memory_region *