On Wed, May 19, 2021 at 1:03 PM Axel Rasmussen axelrasmussen@google.com wrote:
This is a preparatory commit needed before we can use different kinds of backing pages for guest memory.
Previously, we used perf_test_args.host_page_size, which is the host's native page size (commonly 4K). For VM_MEM_SRC_ANONYMOUS this turns out to be okay, but in a follow-up commit we want to allow using different kinds of backing memory.
Take VM_MEM_SRC_ANONYMOUS_HUGETLB for example. Without this change, if we used that backing page type, when we issued a UFFDIO_COPY ioctl we'd only do so with 4K, rather than the full 2M of a backing hugepage. In this case, UFFDIO_COPY returns -EINVAL (__mcopy_atomic_hugetlb checks the size).
Signed-off-by: Axel Rasmussen axelrasmussen@google.com
Reviewed-by: Ben Gardon bgardon@google.com
tools/testing/selftests/kvm/demand_paging_test.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/tools/testing/selftests/kvm/demand_paging_test.c b/tools/testing/selftests/kvm/demand_paging_test.c index 601a1df24dd2..94cf047358d5 100644 --- a/tools/testing/selftests/kvm/demand_paging_test.c +++ b/tools/testing/selftests/kvm/demand_paging_test.c @@ -40,6 +40,7 @@
static int nr_vcpus = 1; static uint64_t guest_percpu_mem_size = DEFAULT_PER_VCPU_MEM_SIZE; +static size_t demand_paging_size; static char *guest_data_prototype;
static void *vcpu_worker(void *data) @@ -85,7 +86,7 @@ static int handle_uffd_page_request(int uffd, uint64_t addr)
copy.src = (uint64_t)guest_data_prototype; copy.dst = addr;
copy.len = perf_test_args.host_page_size;
copy.len = demand_paging_size; copy.mode = 0; clock_gettime(CLOCK_MONOTONIC, &start);@@ -102,7 +103,7 @@ static int handle_uffd_page_request(int uffd, uint64_t addr) PER_PAGE_DEBUG("UFFDIO_COPY %d \t%ld ns\n", tid, timespec_to_ns(ts_diff)); PER_PAGE_DEBUG("Paged in %ld bytes at 0x%lx from thread %d\n",
perf_test_args.host_page_size, addr, tid);
demand_paging_size, addr, tid); return 0;} @@ -261,10 +262,12 @@ static void run_test(enum vm_guest_mode mode, void *arg)
perf_test_args.wr_fract = 1;
guest_data_prototype = malloc(perf_test_args.host_page_size);
demand_paging_size = get_backing_src_pagesz(VM_MEM_SRC_ANONYMOUS);guest_data_prototype = malloc(demand_paging_size); TEST_ASSERT(guest_data_prototype, "Failed to allocate buffer for guest data pattern");
memset(guest_data_prototype, 0xAB, perf_test_args.host_page_size);
memset(guest_data_prototype, 0xAB, demand_paging_size); vcpu_threads = malloc(nr_vcpus * sizeof(*vcpu_threads)); TEST_ASSERT(vcpu_threads, "Memory allocation failed");-- 2.31.1.751.gd2f1c929bd-goog