Re: [PATCH 5/6] KVM: selftests: memslot_perf_test: Consolidate memory sizes

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On 10/18/22 5:36 AM, Maciej S. Szmigiero wrote:
On 14.10.2022 09:19, Gavin Shan wrote:
The addresses and sizes passed to madvise() and vm_userspace_mem_region_add()
should be aligned to host page size, which can be 64KB on aarch64. So it's
wrong by passing additional fixed 4KB memory area to various tests.

Fix it by passing additional fixed 64KB memory area to various tests. After
it's applied, the following command works fine on 64KB-page-size-host and
4KB-page-size-guest.

   # ./memslot_perf_test -v -s 512

Signed-off-by: Gavin Shan <gshan@xxxxxxxxxx>
---
  .../testing/selftests/kvm/memslot_perf_test.c  | 18 ++++++++++--------
  1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/tools/testing/selftests/kvm/memslot_perf_test.c b/tools/testing/selftests/kvm/memslot_perf_test.c
index d587bd952ff9..e6d34744b45d 100644
--- a/tools/testing/selftests/kvm/memslot_perf_test.c
+++ b/tools/testing/selftests/kvm/memslot_perf_test.c
@@ -25,12 +25,14 @@
  #include <kvm_util.h>
  #include <processor.h>
-#define MEM_SIZE        ((512U << 20) + 4096)
-#define MEM_GPA        0x10000000UL
+#define MEM_EXTRA_SIZE        0x10000

So the biggest page size supported right now is 64 KiB - it would be
good to have an assert somewhere to explicitly check for this
(regardless of implicit checks present in other calculations).

Also, an expression like "(64 << 10)" is more readable than a "1"
with a tail of zeroes (it's easy to add one zero too many or be one
zero short).


Yes, it makes sense to me. Lets add check in check_memory_sizes(), which
was added in the previous patch, to fail early if host/guest page size
exceeds 64KB.

   if (host_page_size > SIZE_64KiB || guest_page_size > SIZE_64KiB) {
      pr_info("Unsupported page size on host (0x%x) or guest (0x%x)\n",
              host_page_size, guest_page_size);
   }


For the macros, I think all of us agree on KiB, MiB, GiB, TiB and
their variants :)

Thanks,
Gavin




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