Refactor the guest_memfd selftest to improve test isolation by creating a
a new guest_memfd for each testcase. Currently, the test reuses a single
guest_memfd instance for all testcases, and thus creates dependencies
between tests, e.g. not truncating folios from the guest_memfd instance
at the end of a test could lead to unexpected results (see the PUNCH_HOLE
purging that needs to done by in-flight the NUMA testcases[1]).
Invoke each test via a macro wrapper to create and close a guest_memfd
to cut down on the boilerplate copy+paste needed to create a test.
Link: https://lore.kernel.org/all/20250827175247.83322-10-shivankg@amd.com
Reported-by: Ackerley Tng <ackerleytng@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
.../testing/selftests/kvm/guest_memfd_test.c | 31 ++++++++++---------
1 file changed, 16 insertions(+), 15 deletions(-)
diff --git a/tools/testing/selftests/kvm/guest_memfd_test.c b/tools/testing/selftests/kvm/guest_memfd_test.c
index 8251d019206a..60c6dec63490 100644
--- a/tools/testing/selftests/kvm/guest_memfd_test.c
+++ b/tools/testing/selftests/kvm/guest_memfd_test.c
@@ -26,7 +26,7 @@
static size_t page_size;
-static void test_file_read_write(int fd)
+static void test_file_read_write(int fd, size_t total_size)
{
char buf[64];
@@ -259,14 +259,18 @@ static void test_guest_memfd_flags(struct kvm_vm *vm, uint64_t valid_flags)
}
}
+#define gmem_test(__test, __vm, __flags) \
+do { \
+ int fd = vm_create_guest_memfd(__vm, page_size * 4, __flags); \
+ \
+ test_##__test(fd, page_size * 4); \
+ close(fd); \
+} while (0)
+
static void test_guest_memfd(unsigned long vm_type)
{
uint64_t flags = 0;
struct kvm_vm *vm;
- size_t total_size;
- int fd;
-
- total_size = page_size * 4;
vm = vm_create_barebones_type(vm_type);
@@ -276,24 +280,21 @@ static void test_guest_memfd(unsigned long vm_type)
test_create_guest_memfd_multiple(vm);
test_create_guest_memfd_invalid_sizes(vm, flags);
- fd = vm_create_guest_memfd(vm, total_size, flags);
-
- test_file_read_write(fd);
+ gmem_test(file_read_write, vm, flags);
if (flags & GUEST_MEMFD_FLAG_MMAP) {
- test_mmap_supported(fd, total_size);
- test_fault_overflow(fd, total_size);
+ gmem_test(mmap_supported, vm, flags);
+ gmem_test(fault_overflow, vm, flags);
} else {
- test_mmap_not_supported(fd, total_size);
+ gmem_test(mmap_not_supported, vm, flags);
}
- test_file_size(fd, total_size);
- test_fallocate(fd, total_size);
- test_invalid_punch_hole(fd, total_size);
+ gmem_test(file_size, vm, flags);
+ gmem_test(fallocate, vm, flags);
+ gmem_test(invalid_punch_hole, vm, flags);
test_guest_memfd_flags(vm, flags);
- close(fd);
kvm_vm_free(vm);
}
--
2.51.0.536.g15c5d4f767-googSean Christopherson <seanjc@google.com> writes:
> Refactor the guest_memfd selftest to improve test isolation by creating a
> a new guest_memfd for each testcase. Currently, the test reuses a single
> guest_memfd instance for all testcases, and thus creates dependencies
> between tests, e.g. not truncating folios from the guest_memfd instance
> at the end of a test could lead to unexpected results (see the PUNCH_HOLE
> purging that needs to done by in-flight the NUMA testcases[1]).
>
Lisa and I ran into this recently while working on testing
memory_failure() handling for guest_memfd too.
> Invoke each test via a macro wrapper to create and close a guest_memfd
> to cut down on the boilerplate copy+paste needed to create a test.
>
I introduced a wrapper function but a macro is a better idea since it
also parametrizes the test name.
Reviewed-by: Ackerley Tng <ackerleytng@google.com>
> Link: https://lore.kernel.org/all/20250827175247.83322-10-shivankg@amd.com
> Reported-by: Ackerley Tng <ackerleytng@google.com>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
> .../testing/selftests/kvm/guest_memfd_test.c | 31 ++++++++++---------
> 1 file changed, 16 insertions(+), 15 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/guest_memfd_test.c b/tools/testing/selftests/kvm/guest_memfd_test.c
> index 8251d019206a..60c6dec63490 100644
> --- a/tools/testing/selftests/kvm/guest_memfd_test.c
> +++ b/tools/testing/selftests/kvm/guest_memfd_test.c
> @@ -26,7 +26,7 @@
>
> static size_t page_size;
>
> -static void test_file_read_write(int fd)
> +static void test_file_read_write(int fd, size_t total_size)
> {
> char buf[64];
>
> @@ -259,14 +259,18 @@ static void test_guest_memfd_flags(struct kvm_vm *vm, uint64_t valid_flags)
> }
> }
>
> +#define gmem_test(__test, __vm, __flags) \
> +do { \
> + int fd = vm_create_guest_memfd(__vm, page_size * 4, __flags); \
> + \
> + test_##__test(fd, page_size * 4); \
> + close(fd); \
> +} while (0)
> +
>
> [...snip...]
>
Hi Sean,
On Fri, 26 Sept 2025 at 17:31, Sean Christopherson <seanjc@google.com> wrote:
>
> Refactor the guest_memfd selftest to improve test isolation by creating a
> a new guest_memfd for each testcase. Currently, the test reuses a single
> guest_memfd instance for all testcases, and thus creates dependencies
> between tests, e.g. not truncating folios from the guest_memfd instance
> at the end of a test could lead to unexpected results (see the PUNCH_HOLE
> purging that needs to done by in-flight the NUMA testcases[1]).
>
> Invoke each test via a macro wrapper to create and close a guest_memfd
> to cut down on the boilerplate copy+paste needed to create a test.
>
> Link: https://lore.kernel.org/all/20250827175247.83322-10-shivankg@amd.com
> Reported-by: Ackerley Tng <ackerleytng@google.com>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
> .../testing/selftests/kvm/guest_memfd_test.c | 31 ++++++++++---------
> 1 file changed, 16 insertions(+), 15 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/guest_memfd_test.c b/tools/testing/selftests/kvm/guest_memfd_test.c
> index 8251d019206a..60c6dec63490 100644
> --- a/tools/testing/selftests/kvm/guest_memfd_test.c
> +++ b/tools/testing/selftests/kvm/guest_memfd_test.c
> @@ -26,7 +26,7 @@
>
> static size_t page_size;
>
> -static void test_file_read_write(int fd)
> +static void test_file_read_write(int fd, size_t total_size)
> {
> char buf[64];
>
> @@ -259,14 +259,18 @@ static void test_guest_memfd_flags(struct kvm_vm *vm, uint64_t valid_flags)
> }
> }
>
> +#define gmem_test(__test, __vm, __flags) \
> +do { \
> + int fd = vm_create_guest_memfd(__vm, page_size * 4, __flags); \
> + \
> + test_##__test(fd, page_size * 4); \
> + close(fd); \
> +} while (0)
> +
Can we have a const for total_size that sets it to `page_size * 4`
instead of hardcoding that value twice?
With that:
Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com>
Cheers,
/fuad
> static void test_guest_memfd(unsigned long vm_type)
> {
> uint64_t flags = 0;
> struct kvm_vm *vm;
> - size_t total_size;
> - int fd;
> -
> - total_size = page_size * 4;
>
> vm = vm_create_barebones_type(vm_type);
>
> @@ -276,24 +280,21 @@ static void test_guest_memfd(unsigned long vm_type)
> test_create_guest_memfd_multiple(vm);
> test_create_guest_memfd_invalid_sizes(vm, flags);
>
> - fd = vm_create_guest_memfd(vm, total_size, flags);
> -
> - test_file_read_write(fd);
> + gmem_test(file_read_write, vm, flags);
>
> if (flags & GUEST_MEMFD_FLAG_MMAP) {
> - test_mmap_supported(fd, total_size);
> - test_fault_overflow(fd, total_size);
> + gmem_test(mmap_supported, vm, flags);
> + gmem_test(fault_overflow, vm, flags);
> } else {
> - test_mmap_not_supported(fd, total_size);
> + gmem_test(mmap_not_supported, vm, flags);
> }
>
> - test_file_size(fd, total_size);
> - test_fallocate(fd, total_size);
> - test_invalid_punch_hole(fd, total_size);
> + gmem_test(file_size, vm, flags);
> + gmem_test(fallocate, vm, flags);
> + gmem_test(invalid_punch_hole, vm, flags);
>
> test_guest_memfd_flags(vm, flags);
>
> - close(fd);
> kvm_vm_free(vm);
> }
>
> --
> 2.51.0.536.g15c5d4f767-goog
>
On 26.09.25 18:31, Sean Christopherson wrote: > Refactor the guest_memfd selftest to improve test isolation by creating a > a new guest_memfd for each testcase. Currently, the test reuses a single > guest_memfd instance for all testcases, and thus creates dependencies > between tests, e.g. not truncating folios from the guest_memfd instance > at the end of a test could lead to unexpected results (see the PUNCH_HOLE > purging that needs to done by in-flight the NUMA testcases[1]). > > Invoke each test via a macro wrapper to create and close a guest_memfd > to cut down on the boilerplate copy+paste needed to create a test. > > Link: https://lore.kernel.org/all/20250827175247.83322-10-shivankg@amd.com > Reported-by: Ackerley Tng <ackerleytng@google.com> > Signed-off-by: Sean Christopherson <seanjc@google.com> Reviewed-by: David Hildenbrand <david@redhat.com> -- Cheers David / dhildenb
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