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[173.79.60.52]) by smtp.gmail.com with ESMTPSA id af79cd13be357-9395f18801asm299300585a.16.2026.09.02.12.47.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 02 Sep 2026 12:47:07 -0700 (PDT) From: Gregory Price To: linux-mm@kvack.org Cc: kvm@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@meta.com, pbonzini@redhat.com, seanjc@google.com, akpm@linux-foundation.org, david@kernel.org, ziy@nvidia.com, matthew.brost@intel.com, joshua.hahnjy@gmail.com, rakie.kim@sk.com, byungchul@sk.com, gourry@gourry.net, ying.huang@linux.alibaba.com, apopple@nvidia.com, shuah@kernel.org Subject: [PATCH 5/5] selftests: KVM: guest_memfd: test GUEST_MEMFD_FLAG_BIND_NODE Date: Wed, 2 Sep 2026 15:46:57 -0400 Message-ID: <20260902194657.79075-6-gourry@gourry.net> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260902194657.79075-1-gourry@gourry.net> References: <20260902194657.79075-1-gourry@gourry.net> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Add tests for an umapped guest_memfd mempolicy configured at creation via GUEST_MEMFD_FLAG_BIND_NODE. Handles: - !CONFIG_NUMA (skips) - single node system - multi-node system (faults onto remote node) - invalid arguments (non-zero pad, bad node, node w/o flag). BIND_NODE is skipped in test_guest_memfd_flags() and testing later because that loop asserts every advertised flag succeeds on its own, but BIND_NODE is the only flag that depends on a second field. Signed-off-by: Gregory Price Assisted-by: Claude:claude-opus-5 --- .../testing/selftests/kvm/guest_memfd_test.c | 84 +++++++++++++++++++ 1 file changed, 84 insertions(+) diff --git a/tools/testing/selftests/kvm/guest_memfd_test.c b/tools/testing/selftests/kvm/guest_memfd_test.c index 1818e0fea5690..b333cb42fab29 100644 --- a/tools/testing/selftests/kvm/guest_memfd_test.c +++ b/tools/testing/selftests/kvm/guest_memfd_test.c @@ -196,6 +196,83 @@ static void test_numa_allocation(int fd, size_t total_size) kvm_munmap(mem, total_size); } +static bool has_bind_node(struct kvm_vm *vm) +{ + return vm_check_cap(vm, KVM_CAP_GUEST_MEMFD_FLAGS) & + GUEST_MEMFD_FLAG_BIND_NODE; +} + +static void test_bind_node_invalid(struct kvm_vm *vm, u64 flags) +{ + int fd; + + if (!has_bind_node(vm)) + return; + + fd = __create_guest_memfd_node(vm, page_size, + flags | GUEST_MEMFD_FLAG_BIND_NODE, 0, 1); + TEST_ASSERT(fd < 0 && errno == EINVAL, + "guest_memfd() with non-zero pad should fail with EINVAL"); + + fd = __create_guest_memfd_node(vm, page_size, + flags | GUEST_MEMFD_FLAG_BIND_NODE, + 1 << 20, 0); + TEST_ASSERT(fd < 0 && errno == EINVAL, + "guest_memfd() with out-of-range node should fail with EINVAL"); + + fd = __create_guest_memfd_node(vm, page_size, flags, 1, 0); + TEST_ASSERT(fd < 0 && errno == EINVAL, + "guest_memfd() with a node but no BIND_NODE flag should fail with EINVAL"); +} + +static void test_bind_node(int fd, size_t total_size, int node) +{ + const unsigned long other_mask = 1UL << (node ? 0 : 1); + const unsigned long maxnode = BITS_PER_TYPE(other_mask); + bool steer_away = is_multi_numa_node_system(); + void *pages[4]; + int status[4]; + char *mem; + int i; + + mem = kvm_mmap(total_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd); + for (i = 0; i < 4; i++) + pages[i] = mem + page_size * i; + + /* + * Bind on a different node if possible order to check whether faulting + * happens as desired. Without a second node use the local node and + * just get coverage of create/mmap/fault paths. + */ + if (steer_away) + kvm_set_mempolicy(MPOL_BIND, &other_mask, maxnode); + + /* Deliberately no mbind() on this mapping. */ + memset(mem, 0xaa, total_size); + + kvm_move_pages(0, 4, pages, NULL, status, 0); + for (i = 0; i < 4; i++) + TEST_ASSERT(status[i] == node, + "Expected page %d on node %d, got it on node %d", + i, node, status[i]); + + /* Dropped memory should fault back onto the same node */ + kvm_fallocate(fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, 0, + total_size); + memset(mem, 0xaa, total_size); + + kvm_move_pages(0, 4, pages, NULL, status, 0); + for (i = 0; i < 4; i++) + TEST_ASSERT(status[i] == node, + "Expected page %d back on node %d, got it on node %d", + i, node, status[i]); + + if (steer_away) + kvm_set_mempolicy(MPOL_DEFAULT, NULL, 0); + + kvm_munmap(mem, total_size); +} + static void test_collapse(int fd, u64 flags) { const size_t pmd_size = get_trans_hugepagesz(); @@ -429,6 +506,10 @@ static void test_guest_memfd_flags(struct kvm_vm *vm) int fd; for (flag = BIT(0); flag; flag <<= 1) { + /* BIND_NODE depends on a valid node field, test separately */ + if (flag == GUEST_MEMFD_FLAG_BIND_NODE) + continue; + fd = __vm_create_guest_memfd(vm, page_size, flag); if (flag & valid_flags) { TEST_ASSERT(fd >= 0, @@ -476,6 +557,7 @@ static void __test_guest_memfd(struct kvm_vm *vm, u64 flags) { test_create_guest_memfd_multiple(vm); test_create_guest_memfd_invalid_sizes(vm, flags); + test_bind_node_invalid(vm, flags); gmem_test(file_read_write, vm, flags); @@ -486,6 +568,8 @@ static void __test_guest_memfd(struct kvm_vm *vm, u64 flags) gmem_test(mmap_supported, vm, flags); gmem_test(fault_overflow, vm, flags); gmem_test(numa_allocation, vm, flags); + if (has_bind_node(vm)) + gmem_test_node(bind_node, vm, flags, 0); __gmem_test(collapse, vm, flags, pmd_size); } else { gmem_test(fault_private, vm, flags); -- 2.53.0-Meta