On 23.05.19 19:40, Andrew Jones wrote:
> 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.
I can do
- alignment = huge_page_size;
+ alignment = max(huge_page_size, alignment);
when applying.
>
>> +
>> + /* 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
>>
>
