On Thu, May 23, 2019 at 06:43:05PM +0200, Thomas Huth wrote:
> On s390x, there is a constraint that memory regions have to be aligned
> to 1M (or running the VM will fail). Introduce a new "alignment" variable
> in the vm_userspace_mem_region_add() function which now can be used for
> both, huge page and s390x alignment requirements.
>
> Signed-off-by: Thomas Huth <thuth@xxxxxxxxxx>
> ---
> tools/testing/selftests/kvm/lib/kvm_util.c | 21 ++++++++++++++++-----
> 1 file changed, 16 insertions(+), 5 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
> index 08edb8436c47..656df9d5cd4d 100644
> --- a/tools/testing/selftests/kvm/lib/kvm_util.c
> +++ b/tools/testing/selftests/kvm/lib/kvm_util.c
> @@ -559,6 +559,7 @@ void vm_userspace_mem_region_add(struct kvm_vm *vm,
> unsigned long pmem_size = 0;
> struct userspace_mem_region *region;
> size_t huge_page_size = KVM_UTIL_PGS_PER_HUGEPG * vm->page_size;
> + size_t alignment;
>
> TEST_ASSERT((guest_paddr % vm->page_size) == 0, "Guest physical "
> "address not on a page boundary.\n"
> @@ -608,9 +609,20 @@ void vm_userspace_mem_region_add(struct kvm_vm *vm,
> TEST_ASSERT(region != NULL, "Insufficient Memory");
> region->mmap_size = npages * vm->page_size;
>
> - /* Enough memory to align up to a huge page. */
> +#ifdef __s390x__
> + /* On s390x, the host address must be aligned to 1M (due to PGSTEs) */
> + alignment = 0x100000;
> +#else
> + alignment = 1;
> +#endif
> +
> if (src_type == VM_MEM_SRC_ANONYMOUS_THP)
> - region->mmap_size += huge_page_size;
> + alignment = huge_page_size;
I guess s390x won't ever support VM_MEM_SRC_ANONYMOUS_THP? If it does,
then we need 'alignment = max(huge_page_size, alignment)'. Actually
that might be a nice way to write this anyway for future-proofing.
> +
> + /* Add enough memory to align up if necessary */
> + if (alignment > 1)
> + region->mmap_size += alignment;
> +
> region->mmap_start = mmap(NULL, region->mmap_size,
> PROT_READ | PROT_WRITE,
> MAP_PRIVATE | MAP_ANONYMOUS
> @@ -620,9 +632,8 @@ void vm_userspace_mem_region_add(struct kvm_vm *vm,
> "test_malloc failed, mmap_start: %p errno: %i",
> region->mmap_start, errno);
>
> - /* Align THP allocation up to start of a huge page. */
> - region->host_mem = align(region->mmap_start,
> - src_type == VM_MEM_SRC_ANONYMOUS_THP ? huge_page_size : 1);
> + /* Align host address */
> + region->host_mem = align(region->mmap_start, alignment);
>
> /* As needed perform madvise */
> if (src_type == VM_MEM_SRC_ANONYMOUS || src_type == VM_MEM_SRC_ANONYMOUS_THP) {
> --
> 2.21.0
>
