Re: [PATCH v8 29/46] KVM: selftests: Add selftests global for guest memory attributes capability

[Fuad Tabba]

On Fri, 19 Jun 2026 at 01:32, Ackerley Tng via B4 Relay
<devnull+ackerleytng.google.com@xxxxxxxxxx> wrote:
>
> From: Sean Christopherson <seanjc@xxxxxxxxxx>
>
> 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@xxxxxxxxxx>
> Signed-off-by: Ackerley Tng <ackerleytng@xxxxxxxxxx>

Reviewed-by: Fuad Tabba <tabba@xxxxxxxxxx>

Cheers,
/fuad

> ---
>  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 a56271c237ae9..51287fac8138a 100644
> --- a/tools/testing/selftests/kvm/include/test_util.h
> +++ b/tools/testing/selftests/kvm/include/test_util.h
> @@ -115,6 +115,8 @@ struct guest_random_state {
>  extern u32 guest_random_seed;
>  extern struct guest_random_state guest_rng;
>
> +extern bool kvm_has_gmem_attributes;
> +
>  struct guest_random_state new_guest_random_state(u32 seed);
>  u32 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 d5bbc80b2bf1c..b73817f7bc803 100644
> --- a/tools/testing/selftests/kvm/lib/kvm_util.c
> +++ b/tools/testing/selftests/kvm/lib/kvm_util.c
> @@ -24,6 +24,8 @@ u32 guest_random_seed;
>  struct guest_random_state guest_rng;
>  static u32 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, u32 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);
>
> @@ -2286,6 +2289,8 @@ 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();
>  }
>
>
> --
> 2.55.0.rc0.738.g0c8ab3ebcc-goog
>
>