Re: [PATCH v2 07/10] KVM: selftests: add shmem backing source type

On Wed, May 19, 2021 at 1:04 PM Axel Rasmussen axelrasmussen@google.com wrote:

This lets us run the demand paging test on top of a shmem-backed area. In follow-up commits, we'll 1) leverage this new capability to create an alias mapping, and then 2) use the alias mapping to exercise UFFD minor faults.

Signed-off-by: Axel Rasmussen axelrasmussen@google.com

tools/testing/selftests/kvm/include/test_util.h | 1 + tools/testing/selftests/kvm/lib/kvm_util.c | 15 +++++++++++++++ tools/testing/selftests/kvm/lib/test_util.c | 5 +++++ 3 files changed, 21 insertions(+)

diff --git a/tools/testing/selftests/kvm/include/test_util.h b/tools/testing/selftests/kvm/include/test_util.h index fade3130eb01..7377f00469ef 100644 --- a/tools/testing/selftests/kvm/include/test_util.h +++ b/tools/testing/selftests/kvm/include/test_util.h @@ -84,6 +84,7 @@ enum vm_mem_backing_src_type { VM_MEM_SRC_ANONYMOUS_HUGETLB_1GB, VM_MEM_SRC_ANONYMOUS_HUGETLB_2GB, VM_MEM_SRC_ANONYMOUS_HUGETLB_16GB,

•   VM_MEM_SRC_SHMEM,
    NUM_SRC_TYPES,
  

};

diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c index bc405785ac8b..e4a8d0c43c5e 100644 --- a/tools/testing/selftests/kvm/lib/kvm_util.c +++ b/tools/testing/selftests/kvm/lib/kvm_util.c @@ -757,6 +757,21 @@ void vm_userspace_mem_region_add(struct kvm_vm *vm, if (alignment > 1) region->mmap_size += alignment;

•   region->fd = -1;
  

Ah I guess this is the corresponding change from the previous patch.

•   if (src_type == VM_MEM_SRC_SHMEM) {
  

•           region->fd = memfd_create("kvm_selftest", MFD_CLOEXEC);
  

•           TEST_ASSERT(region->fd != -1,
  

•                       "memfd_create failed, errno: %i", errno);
  

•           ret = ftruncate(region->fd, region->mmap_size);
  

•           TEST_ASSERT(ret == 0, "ftruncate failed, errno: %i", errno);
  

•           ret = fallocate(region->fd,
  

•                           FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, 0,
  

•                           region->mmap_size);
  

•           TEST_ASSERT(ret == 0, "fallocate failed, errno: %i", errno);
  

•   }
  

•   region->mmap_start = mmap(NULL, region->mmap_size,
                              PROT_READ | PROT_WRITE,
                              vm_mem_backing_src_alias(src_type)->flag,
  

diff --git a/tools/testing/selftests/kvm/lib/test_util.c b/tools/testing/selftests/kvm/lib/test_util.c index 06ddde068736..c7a265da5090 100644 --- a/tools/testing/selftests/kvm/lib/test_util.c +++ b/tools/testing/selftests/kvm/lib/test_util.c @@ -236,6 +236,10 @@ const struct vm_mem_backing_src_alias *vm_mem_backing_src_alias(uint32_t i) .name = "anonymous_hugetlb_16gb", .flag = anon_huge_flags | MAP_HUGE_16GB, },

•           [VM_MEM_SRC_SHMEM] = {
  

•                   .name = "shmem",
  

•                   .flag = MAP_SHARED,
  

•           },
    };
    _Static_assert(ARRAY_SIZE(aliases) == NUM_SRC_TYPES,
                   "Missing new backing src types?");
  

@@ -253,6 +257,7 @@ size_t get_backing_src_pagesz(uint32_t i)

    switch (i) {
    case VM_MEM_SRC_ANONYMOUS:

•   case VM_MEM_SRC_SHMEM:
            return getpagesize();
    case VM_MEM_SRC_ANONYMOUS_THP:
            return get_trans_hugepagesz();
  

-- 2.31.1.751.gd2f1c929bd-goog