[PATCH] kvm powerpc/book3s-apiv2: Add suite initialization to skip GSB tests without APIv2 support

[Vaibhav Jain <vaibhav@linux.ibm.com>]

The guest state buffer (GSB) test suite currently fails on systems that
do not support the PAPR APIv2 nested virtualization. This happens because
the tests attempt to use APIv2-specific functionality without first
checking if the host supports it. This was recently reported [1] when
test-guest-state-buffer kunit tests were being run on Qemu without enabling
Qemu capability 'cap-nested-papr' which enabled APIv2 nested virtualization
for PPC64 Pseries Qemu machine.

Add a suite_init callback that checks for APIv2 support by calling
plpar_guest_get_capabilities(). If the host does not support APIv2
(indicated by H_SUCCESS not being returned), mark all test cases in the
suite as KUNIT_SKIPPED. This prevents test failures on systems without
APIv2 support while still allowing the tests to run on capable systems.

[1] https://lore.kernel.org/all/20260603064225.GC18149@sol/

Reported-by: Eric Biggers <ebiggers@kernel.org>
Closes: https://lore.kernel.org/all/20260603064225.GC18149@sol
Signed-off-by: Vaibhav Jain <vaibhav@linux.ibm.com>
Assisted-by: Bob:Claude-3.7-Sonnet Bob-Shell
---
 arch/powerpc/kvm/test-guest-state-buffer.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/arch/powerpc/kvm/test-guest-state-buffer.c b/arch/powerpc/kvm/test-guest-state-buffer.c
index 5ccca306997a..f84b40fa55db 100644
--- a/arch/powerpc/kvm/test-guest-state-buffer.c
+++ b/arch/powerpc/kvm/test-guest-state-buffer.c
@@ -521,6 +521,24 @@ static void test_gs_hostwide_counters(struct kunit *test)
 	kvmppc_gsb_free(gsb);
 }
 
+static int init_gs_test_suite(struct kunit_suite *suite)
+{
+	long rc;
+	unsigned long host_capabilities;
+	struct kunit_case *test_case;
+
+	/* Enable test suite only if APIv2 is supported */
+	rc = plpar_guest_get_capabilities(0, &host_capabilities);
+
+	if (rc != H_SUCCESS) {
+		/* Skip all testcases if no APIv2 support */
+		kunit_suite_for_each_test_case(suite, test_case)
+			WRITE_ONCE(test_case->status, KUNIT_SKIPPED);
+	}
+
+	return 0;
+}
+
 static struct kunit_case guest_state_buffer_testcases[] = {
 	KUNIT_CASE(test_creating_buffer),
 	KUNIT_CASE(test_adding_element),
@@ -535,6 +553,7 @@ static struct kunit_case guest_state_buffer_testcases[] = {
 static struct kunit_suite guest_state_buffer_test_suite = {
 	.name = "guest_state_buffer_test",
 	.test_cases = guest_state_buffer_testcases,
+	.suite_init = init_gs_test_suite,
 };
 
 kunit_test_suites(&guest_state_buffer_test_suite);
-- 
2.54.0