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Message-ID: <322b245180f09076c5cbbac0d68ea27c0a8c878b.1747264138.git.ackerleytng@google.com>
Date: Wed, 14 May 2025 16:42:21 -0700
From: Ackerley Tng <ackerleytng@...gle.com>
To: kvm@...r.kernel.org, linux-mm@...ck.org, linux-kernel@...r.kernel.org,
x86@...nel.org, linux-fsdevel@...r.kernel.org
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Subject: [RFC PATCH v2 42/51] KVM: selftests: Add basic selftests for
hugetlb-backed guest_memfd
Add tests for 2MB and 1GB page sizes, and update the invalid flags
test for GUEST_MEMFD_FLAG_HUGETLB.
In tests, touch every page but not every byte in page to save time
while testing.
Change-Id: I7d80a12b991a064cfd796e3c6e11f9a95fd16ec1
Signed-off-by: Ackerley Tng <ackerleytng@...gle.com>
---
.../testing/selftests/kvm/guest_memfd_test.c | 94 +++++++++++++------
1 file changed, 67 insertions(+), 27 deletions(-)
diff --git a/tools/testing/selftests/kvm/guest_memfd_test.c b/tools/testing/selftests/kvm/guest_memfd_test.c
index 1e79382fd830..c8acccaa9e1d 100644
--- a/tools/testing/selftests/kvm/guest_memfd_test.c
+++ b/tools/testing/selftests/kvm/guest_memfd_test.c
@@ -13,6 +13,8 @@
#include <linux/bitmap.h>
#include <linux/falloc.h>
+#include <linux/guestmem.h>
+#include <linux/sizes.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
@@ -38,6 +40,7 @@ static void test_file_read_write(int fd)
static void test_faulting_allowed(int fd, size_t page_size, size_t total_size)
{
const char val = 0xaa;
+ size_t increment;
char *mem;
size_t i;
int ret;
@@ -45,21 +48,25 @@ static void test_faulting_allowed(int fd, size_t page_size, size_t total_size)
mem = mmap(NULL, total_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
TEST_ASSERT(mem != MAP_FAILED, "mmaping() guest memory should pass.");
- memset(mem, val, total_size);
- for (i = 0; i < total_size; i++)
+ increment = page_size >> 1;
+
+ for (i = 0; i < total_size; i += increment)
+ mem[i] = val;
+ for (i = 0; i < total_size; i += increment)
TEST_ASSERT_EQ(mem[i], val);
ret = fallocate(fd, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE, 0,
page_size);
TEST_ASSERT(!ret, "fallocate the first page should succeed");
- for (i = 0; i < page_size; i++)
+ for (i = 0; i < page_size; i += increment)
TEST_ASSERT_EQ(mem[i], 0x00);
- for (; i < total_size; i++)
+ for (; i < total_size; i += increment)
TEST_ASSERT_EQ(mem[i], val);
- memset(mem, val, total_size);
- for (i = 0; i < total_size; i++)
+ for (i = 0; i < total_size; i += increment)
+ mem[i] = val;
+ for (i = 0; i < total_size; i += increment)
TEST_ASSERT_EQ(mem[i], val);
ret = munmap(mem, total_size);
@@ -209,7 +216,7 @@ static void test_create_guest_memfd_invalid_sizes(struct kvm_vm *vm,
size_t size;
int fd;
- for (size = 1; size < page_size; size++) {
+ for (size = 1; size < page_size; size += (page_size >> 1)) {
fd = __vm_create_guest_memfd(vm, size, guest_memfd_flags);
TEST_ASSERT(fd == -1 && errno == EINVAL,
"guest_memfd() with non-page-aligned page size '0x%lx' should fail with EINVAL",
@@ -217,28 +224,33 @@ static void test_create_guest_memfd_invalid_sizes(struct kvm_vm *vm,
}
}
-static void test_create_guest_memfd_multiple(struct kvm_vm *vm)
+static void test_create_guest_memfd_multiple(struct kvm_vm *vm,
+ uint64_t guest_memfd_flags,
+ size_t page_size)
{
int fd1, fd2, ret;
struct stat st1, st2;
- fd1 = __vm_create_guest_memfd(vm, 4096, 0);
+ fd1 = __vm_create_guest_memfd(vm, page_size, guest_memfd_flags);
TEST_ASSERT(fd1 != -1, "memfd creation should succeed");
ret = fstat(fd1, &st1);
TEST_ASSERT(ret != -1, "memfd fstat should succeed");
- TEST_ASSERT(st1.st_size == 4096, "memfd st_size should match requested size");
+ TEST_ASSERT(st1.st_size == page_size, "memfd st_size should match requested size");
- fd2 = __vm_create_guest_memfd(vm, 8192, 0);
+ fd2 = __vm_create_guest_memfd(vm, page_size * 2, guest_memfd_flags);
TEST_ASSERT(fd2 != -1, "memfd creation should succeed");
ret = fstat(fd2, &st2);
TEST_ASSERT(ret != -1, "memfd fstat should succeed");
- TEST_ASSERT(st2.st_size == 8192, "second memfd st_size should match requested size");
+ TEST_ASSERT(st2.st_size == page_size * 2,
+ "second memfd st_size should match requested size");
+
ret = fstat(fd1, &st1);
TEST_ASSERT(ret != -1, "memfd fstat should succeed");
- TEST_ASSERT(st1.st_size == 4096, "first memfd st_size should still match requested size");
+ TEST_ASSERT(st1.st_size == page_size,
+ "first memfd st_size should still match requested size");
TEST_ASSERT(st1.st_ino != st2.st_ino, "different memfd should have different inode numbers");
close(fd2);
@@ -449,21 +461,13 @@ static void test_guest_memfd_features(struct kvm_vm *vm, size_t page_size,
close(fd);
}
-static void test_with_type(unsigned long vm_type, uint64_t guest_memfd_flags,
- bool expect_mmap_allowed)
+static void test_guest_memfd_features_for_page_size(struct kvm_vm *vm,
+ uint64_t guest_memfd_flags,
+ size_t page_size,
+ bool expect_mmap_allowed)
{
- struct kvm_vm *vm;
- size_t page_size;
+ test_create_guest_memfd_multiple(vm, guest_memfd_flags, page_size);
- if (!(kvm_check_cap(KVM_CAP_VM_TYPES) & BIT(vm_type)))
- return;
-
- vm = vm_create_barebones_type(vm_type);
-
- test_create_guest_memfd_multiple(vm);
- test_bind_guest_memfd_wrt_userspace_addr(vm);
-
- page_size = getpagesize();
if (guest_memfd_flags & GUEST_MEMFD_FLAG_SUPPORT_SHARED) {
test_guest_memfd_features(vm, page_size, guest_memfd_flags,
expect_mmap_allowed, true);
@@ -479,6 +483,34 @@ static void test_with_type(unsigned long vm_type, uint64_t guest_memfd_flags,
test_guest_memfd_features(vm, page_size, guest_memfd_flags,
expect_mmap_allowed, false);
}
+}
+
+static void test_with_type(unsigned long vm_type, uint64_t base_flags,
+ bool expect_mmap_allowed)
+{
+ struct kvm_vm *vm;
+ uint64_t flags;
+
+ if (!(kvm_check_cap(KVM_CAP_VM_TYPES) & BIT(vm_type)))
+ return;
+
+ vm = vm_create_barebones_type(vm_type);
+
+ test_bind_guest_memfd_wrt_userspace_addr(vm);
+
+ printf("Test guest_memfd with 4K pages for vm_type %ld\n", vm_type);
+ test_guest_memfd_features_for_page_size(vm, base_flags, getpagesize(), expect_mmap_allowed);
+ printf("\tPASSED\n");
+
+ printf("Test guest_memfd with 2M pages for vm_type %ld\n", vm_type);
+ flags = base_flags | GUEST_MEMFD_FLAG_HUGETLB | GUESTMEM_HUGETLB_FLAG_2MB;
+ test_guest_memfd_features_for_page_size(vm, flags, SZ_2M, expect_mmap_allowed);
+ printf("\tPASSED\n");
+
+ printf("Test guest_memfd with 1G pages for vm_type %ld\n", vm_type);
+ flags = base_flags | GUEST_MEMFD_FLAG_HUGETLB | GUESTMEM_HUGETLB_FLAG_1GB;
+ test_guest_memfd_features_for_page_size(vm, flags, SZ_1G, expect_mmap_allowed);
+ printf("\tPASSED\n");
kvm_vm_release(vm);
}
@@ -486,9 +518,14 @@ static void test_with_type(unsigned long vm_type, uint64_t guest_memfd_flags,
static void test_vm_with_gmem_flag(struct kvm_vm *vm, uint64_t flag,
bool expect_valid)
{
- size_t page_size = getpagesize();
+ size_t page_size;
int fd;
+ if (flag == GUEST_MEMFD_FLAG_HUGETLB)
+ page_size = get_def_hugetlb_pagesz();
+ else
+ page_size = getpagesize();
+
fd = __vm_create_guest_memfd(vm, page_size, flag);
if (expect_valid) {
@@ -550,6 +587,9 @@ static void test_gmem_flag_validity(void)
/* After conversions are supported, all VM types support shared mem. */
uint64_t valid_flags = GUEST_MEMFD_FLAG_SUPPORT_SHARED;
+ if (kvm_has_cap(KVM_CAP_GMEM_HUGETLB))
+ valid_flags |= GUEST_MEMFD_FLAG_HUGETLB;
+
test_vm_type_gmem_flag_validity(VM_TYPE_DEFAULT, valid_flags);
#ifdef __x86_64__
--
2.49.0.1045.g170613ef41-goog
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