[PATCH v6 5/5] KVM: guest_memfd: selftests: add tests for mmap and NUMA policy support

[Shivank Garg <shivankg@amd.com>]

Add tests for memory mapping and NUMA memory policy binding in
guest_memfd. This extends the existing selftests by adding proper
validation for:
- Basic mmap() functionality
- KVM GMEM set_policy and get_policy() vm_ops functionality using
  mbind() and get_mempolicy()
- NUMA policy application before and after memory allocation

These tests help ensure NUMA support for guest_memfd works correctly.

Signed-off-by: Shivank Garg <shivankg@amd.com>
---
 .../testing/selftests/kvm/guest_memfd_test.c  | 86 ++++++++++++++++++-
 1 file changed, 82 insertions(+), 4 deletions(-)

diff --git a/tools/testing/selftests/kvm/guest_memfd_test.c b/tools/testing/selftests/kvm/guest_memfd_test.c
index ce687f8d248f..b9c845cc41e0 100644
--- a/tools/testing/selftests/kvm/guest_memfd_test.c
+++ b/tools/testing/selftests/kvm/guest_memfd_test.c
@@ -13,9 +13,11 @@
 
 #include <linux/bitmap.h>
 #include <linux/falloc.h>
+#include <linux/mempolicy.h>
 #include <sys/mman.h>
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <sys/syscall.h>
 
 #include "kvm_util.h"
 #include "test_util.h"
@@ -34,12 +36,86 @@ static void test_file_read_write(int fd)
 		    "pwrite on a guest_mem fd should fail");
 }
 
-static void test_mmap(int fd, size_t page_size)
+static void test_mmap(int fd, size_t page_size, size_t total_size)
 {
 	char *mem;
 
-	mem = mmap(NULL, page_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
-	TEST_ASSERT_EQ(mem, MAP_FAILED);
+	mem = mmap(NULL, total_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+	TEST_ASSERT(mem != MAP_FAILED, "mmap should succeed");
+	TEST_ASSERT(munmap(mem, total_size) == 0, "munmap should succeed");
+}
+
+static void test_mbind(int fd, size_t page_size, size_t total_size)
+{
+	unsigned long nodemask = 1; /* nid: 0 */
+	unsigned long maxnode = 8;
+	unsigned long get_nodemask;
+	int get_policy;
+	void *mem;
+	int ret;
+
+	mem = mmap(NULL, total_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+	TEST_ASSERT(mem != MAP_FAILED, "mmap for mbind test should succeed");
+
+	/* Test MPOL_INTERLEAVE policy */
+	ret = syscall(__NR_mbind, mem, page_size * 2, MPOL_INTERLEAVE,
+		      &nodemask, maxnode, 0);
+	TEST_ASSERT(!ret, "mbind with INTERLEAVE to node 0 should succeed");
+	ret = syscall(__NR_get_mempolicy, &get_policy, &get_nodemask,
+		      maxnode, mem, MPOL_F_ADDR);
+	TEST_ASSERT(!ret && get_policy == MPOL_INTERLEAVE && get_nodemask == nodemask,
+		    "Policy should be MPOL_INTERLEAVE and nodes match");
+
+	/* Test basic MPOL_BIND policy */
+	ret = syscall(__NR_mbind, mem + page_size * 2, page_size * 2, MPOL_BIND,
+		      &nodemask, maxnode, 0);
+	TEST_ASSERT(!ret, "mbind with MPOL_BIND to node 0 should succeed");
+	ret = syscall(__NR_get_mempolicy, &get_policy, &get_nodemask,
+		      maxnode, mem + page_size * 2, MPOL_F_ADDR);
+	TEST_ASSERT(!ret && get_policy == MPOL_BIND && get_nodemask == nodemask,
+		    "Policy should be MPOL_BIND and nodes match");
+
+	/* Test MPOL_DEFAULT policy */
+	ret = syscall(__NR_mbind, mem, total_size, MPOL_DEFAULT, NULL, 0, 0);
+	TEST_ASSERT(!ret, "mbind with MPOL_DEFAULT should succeed");
+	ret = syscall(__NR_get_mempolicy, &get_policy, &get_nodemask,
+		      maxnode, mem, MPOL_F_ADDR);
+	TEST_ASSERT(!ret && get_policy == MPOL_DEFAULT && get_nodemask == 0,
+		    "Policy should be MPOL_DEFAULT and nodes zero");
+
+	/* Test with invalid policy */
+	ret = syscall(__NR_mbind, mem, page_size, 999, &nodemask, maxnode, 0);
+	TEST_ASSERT(ret == -1 && errno == EINVAL,
+		    "mbind with invalid policy should fail with EINVAL");
+
+	TEST_ASSERT(munmap(mem, total_size) == 0, "munmap should succeed");
+}
+
+static void test_numa_allocation(int fd, size_t page_size, size_t total_size)
+{
+	unsigned long nodemask = 1;  /* Node 0 */
+	unsigned long maxnode = 8;
+	void *mem;
+	int ret;
+
+	mem = mmap(NULL, total_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+	TEST_ASSERT(mem != MAP_FAILED, "mmap should succeed");
+
+	/* Set NUMA policy after allocation */
+	ret = fallocate(fd, FALLOC_FL_KEEP_SIZE, 0, page_size * 2);
+	TEST_ASSERT(!ret, "fallocate with aligned offset and size should succeed");
+	ret = syscall(__NR_mbind, mem, page_size * 2, MPOL_BIND, &nodemask,
+		      maxnode, 0);
+	TEST_ASSERT(!ret, "mbind should succeed");
+
+	/* Set NUMA policy before allocation */
+	ret = syscall(__NR_mbind, mem + page_size * 2, page_size, MPOL_BIND,
+		      &nodemask, maxnode, 0);
+	TEST_ASSERT(!ret, "mbind should succeed");
+	ret = fallocate(fd, FALLOC_FL_KEEP_SIZE, page_size * 2, page_size * 2);
+	TEST_ASSERT(!ret, "fallocate with aligned offset and size should succeed");
+
+	TEST_ASSERT(munmap(mem, total_size) == 0, "munmap should succeed");
 }
 
 static void test_file_size(int fd, size_t page_size, size_t total_size)
@@ -190,7 +266,9 @@ int main(int argc, char *argv[])
 	fd = vm_create_guest_memfd(vm, total_size, 0);
 
 	test_file_read_write(fd);
-	test_mmap(fd, page_size);
+	test_mmap(fd, page_size, total_size);
+	test_mbind(fd, page_size, total_size);
+	test_numa_allocation(fd, page_size, total_size);
 	test_file_size(fd, page_size, total_size);
 	test_fallocate(fd, page_size, total_size);
 	test_invalid_punch_hole(fd, page_size, total_size);
-- 
2.34.1