[PATCH RFC v4 21/44] KVM: selftests: Add selftests global for guest memory attributes capability

Ackerley Tng
2026-03-26T22:25:18Z

From: Sean Christopherson <seanjc@google.com>

Add a global variable, kvm_has_gmem_attributes, to make the result of
checking for KVM_CAP_GUEST_MEMFD_MEMORY_ATTRIBUTES available to all tests.

kvm_has_gmem_attributes is true if guest_memfd tracks memory attributes, as
opposed to VM-level tracking.

This global variable is synced to the guest for testing convenience, to
avoid introducing subtle bugs when host/guest state is desynced.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Ackerley Tng <ackerleytng@google.com>
---
tools/testing/selftests/kvm/include/test_util.h | 2 ++
tools/testing/selftests/kvm/lib/kvm_util.c | 5 +++++
2 files changed, 7 insertions(+)

diff --git a/tools/testing/selftests/kvm/include/test_util.h b/tools/testing/selftests/kvm/include/test_util.h
index b4872ba8ed124..2871a42928471 100644
--- a/tools/testing/selftests/kvm/include/test_util.h
+++ b/tools/testing/selftests/kvm/include/test_util.h
@@ -113,6 +113,8 @@ struct guest_random_state {
extern uint32_t guest_random_seed;
extern struct guest_random_state guest_rng;

+extern bool kvm_has_gmem_attributes;
+
struct guest_random_state new_guest_random_state(uint32_t seed);
uint32_t guest_random_u32(struct guest_random_state *state);

diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index 82d6945efa29a..404efb5318f09 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -24,6 +24,8 @@ uint32_t guest_random_seed;
struct guest_random_state guest_rng;
static uint32_t last_guest_seed;

+bool kvm_has_gmem_attributes;
+
static size_t vcpu_mmap_sz(void);

int __open_path_or_exit(const char *path, int flags, const char *enoent_help)
@@ -521,6 +523,7 @@ struct kvm_vm *__vm_create(struct vm_shape shape, uint32_t nr_runnable_vcpus,
}
guest_rng = new_guest_random_state(guest_random_seed);
sync_global_to_guest(vm, guest_rng);
+ sync_global_to_guest(vm, kvm_has_gmem_attributes);

kvm_arch_vm_post_create(vm, nr_runnable_vcpus);

@@ -2365,6 +2368,8 @@ void __attribute((constructor)) kvm_selftest_init(void)
guest_random_seed = last_guest_seed = random();
pr_info("Random seed: 0x%x\n", guest_random_seed);

+ kvm_has_gmem_attributes = kvm_has_cap(KVM_CAP_GUEST_MEMFD_MEMORY_ATTRIBUTES);
+
kvm_selftest_arch_init();
}

--
2.53.0.1018.g2bb0e51243-goog