linux-kernel - [PATCH] KVM: selftests: Refactor stable TSC check to use TEST

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Date:   Wed,  5 Apr 2023 17:17:24 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Hao Ge <gehao@...inos.cn>, Vipin Sharma <vipinsh@...gle.com>,
        Sean Christopherson <seanjc@...gle.com>
Subject: [PATCH] KVM: selftests: Refactor stable TSC check to use TEST_REQUIRE()

Refactor the nested TSC scaling test's check on a stable system TSC to
use TEST_REQUIRE() to do the heavy lifting when the system doesn't have
a stable TSC.  Using a helper+TEST_REQUIRE() eliminates the need for
gotos and a custom message.

Cc: Hao Ge <gehao@...inos.cn>
Cc: Vipin Sharma <vipinsh@...gle.com>
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 .../kvm/x86_64/vmx_nested_tsc_scaling_test.c  | 22 ++++++-------------
 1 file changed, 7 insertions(+), 15 deletions(-)

diff --git a/tools/testing/selftests/kvm/x86_64/vmx_nested_tsc_scaling_test.c b/tools/testing/selftests/kvm/x86_64/vmx_nested_tsc_scaling_test.c
index fa03c8d1ce4e..e710b6e7fb38 100644
--- a/tools/testing/selftests/kvm/x86_64/vmx_nested_tsc_scaling_test.c
+++ b/tools/testing/selftests/kvm/x86_64/vmx_nested_tsc_scaling_test.c
@@ -116,29 +116,21 @@ static void l1_guest_code(struct vmx_pages *vmx_pages)
 	GUEST_DONE();
 }
 
-static void stable_tsc_check_supported(void)
+static bool system_has_stable_tsc(void)
 {
+	bool tsc_is_stable;
 	FILE *fp;
 	char buf[4];
 
 	fp = fopen("/sys/devices/system/clocksource/clocksource0/current_clocksource", "r");
 	if (fp == NULL)
-		goto skip_test;
+		return false;
 
-	if (fgets(buf, sizeof(buf), fp) == NULL)
-		goto close_fp;
+	tsc_is_stable = fgets(buf, sizeof(buf), fp) &&
+			!strncmp(buf, "tsc", sizeof(buf));
 
-	if (strncmp(buf, "tsc", sizeof(buf)))
-		goto close_fp;
-
-	fclose(fp);
-	return;
-
-close_fp:
 	fclose(fp);
-skip_test:
-	print_skip("Kernel does not use TSC clocksource - assuming that host TSC is not stable");
-	exit(KSFT_SKIP);
+	return tsc_is_stable;
 }
 
 int main(int argc, char *argv[])
@@ -156,7 +148,7 @@ int main(int argc, char *argv[])
 
 	TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_VMX));
 	TEST_REQUIRE(kvm_has_cap(KVM_CAP_TSC_CONTROL));
-	stable_tsc_check_supported();
+	TEST_REQUIRE(system_has_stable_tsc());
 
 	/*
 	 * We set L1's scale factor to be a random number from 2 to 10.

base-commit: 7712145073876092e9aa81f0b836fef8b5694b14
-- 
2.40.0.348.gf938b09366-goog