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

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 <[email protected]>
Closes: https://lore.kernel.org/all/20260603064225.GC18149@sol
Signed-off-by: Vaibhav Jain <[email protected]>
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