On 16/05/2019 13.30, David Hildenbrand wrote: > On 16.05.19 13:12, 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 8d63ccb93e10..64a0da6efe3d 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; > > This corresponds to huge_page_size, maybe you can exploit this fact here. > > Something like > > alignment = 1; > > /* On s390x, the host address must always be aligned to the THP size */ > #ifndef __s390x__ > if (src_type == VM_MEM_SRC_ANONYMOUS_THP) > #endif > alignment = huge_page_size; > > Maybe in a nicer fashion. Not sure. Hmm, but if I've got your explanation on IRC right, it's rather a coincidence that the huge page size matches the alignment requirements for KVM memslots, isn't it? So I think the code would look rather confusing if I'd try to shorten it this way...? Thomas
