linux-kernel - [PATCH v7 04/10] KVM: selftests: Add SMT control state helper

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Message-ID: <20250221210200.244405-5-prsampat@amd.com>
Date: Fri, 21 Feb 2025 15:01:54 -0600
From: "Pratik R. Sampat" <prsampat@....com>
To: <linux-kernel@...r.kernel.org>, <x86@...nel.org>, <kvm@...r.kernel.org>,
	<linux-crypto@...r.kernel.org>, <linux-kselftest@...r.kernel.org>
CC: <seanjc@...gle.com>, <pbonzini@...hat.com>, <thomas.lendacky@....com>,
	<tglx@...utronix.de>, <mingo@...hat.com>, <bp@...en8.de>,
	<dave.hansen@...ux.intel.com>, <shuah@...nel.org>, <pgonda@...gle.com>,
	<ashish.kalra@....com>, <nikunj@....com>, <pankaj.gupta@....com>,
	<michael.roth@....com>, <sraithal@....com>, <prsampat@....com>
Subject: [PATCH v7 04/10] KVM: selftests: Add SMT control state helper

Move the SMT control check out of the hyperv_cpuid selftest so that
it is generally accessible all selftests. Split the functionality into
a helper that populates a buffer with SMT control value which other
helpers can use to ascertain if SMT state is available and active.

Signed-off-by: Pratik R. Sampat <prsampat@....com>
---
v6..v7:

* New - Implement SMT control interface within kvm_util so that it is
  accessible to KVM KSTs and subsequently the SEV library (Sean)
---
 .../testing/selftests/kvm/include/kvm_util.h  | 35 +++++++++++++++++++
 .../testing/selftests/kvm/x86/hyperv_cpuid.c  | 19 ----------
 2 files changed, 35 insertions(+), 19 deletions(-)

diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
index 4c4e5a847f67..446f04b2710f 100644
--- a/tools/testing/selftests/kvm/include/kvm_util.h
+++ b/tools/testing/selftests/kvm/include/kvm_util.h
@@ -542,6 +542,41 @@ static inline uint64_t vm_get_stat(struct kvm_vm *vm, const char *stat_name)
 	return data;
 }
 
+static inline bool read_smt_control(char *buf, size_t buf_size)
+{
+	FILE *f = fopen("/sys/devices/system/cpu/smt/control", "r");
+	bool ret;
+
+	if (!f)
+		return false;
+
+	ret = fread(buf, sizeof(*buf), buf_size, f) > 0;
+	fclose(f);
+
+	return ret;
+}
+
+static inline bool smt_possible(void)
+{
+	char buf[16];
+
+	if (read_smt_control(buf, sizeof(buf)) &&
+	    (!strncmp(buf, "forceoff", 8) || !strncmp(buf, "notsupported", 12)))
+		return false;
+
+	return true;
+}
+
+static inline bool smt_on(void)
+{
+	char buf[16];
+
+	if (read_smt_control(buf, sizeof(buf)) && !strncmp(buf, "on", 2))
+		return true;
+
+	return false;
+}
+
 void vm_create_irqchip(struct kvm_vm *vm);
 
 static inline int __vm_create_guest_memfd(struct kvm_vm *vm, uint64_t size,
diff --git a/tools/testing/selftests/kvm/x86/hyperv_cpuid.c b/tools/testing/selftests/kvm/x86/hyperv_cpuid.c
index 4e920705681a..1eb55d0b7297 100644
--- a/tools/testing/selftests/kvm/x86/hyperv_cpuid.c
+++ b/tools/testing/selftests/kvm/x86/hyperv_cpuid.c
@@ -22,25 +22,6 @@ static void guest_code(void)
 {
 }
 
-static bool smt_possible(void)
-{
-	char buf[16];
-	FILE *f;
-	bool res = true;
-
-	f = fopen("/sys/devices/system/cpu/smt/control", "r");
-	if (f) {
-		if (fread(buf, sizeof(*buf), sizeof(buf), f) > 0) {
-			if (!strncmp(buf, "forceoff", 8) ||
-			    !strncmp(buf, "notsupported", 12))
-				res = false;
-		}
-		fclose(f);
-	}
-
-	return res;
-}
-
 static void test_hv_cpuid(struct kvm_vcpu *vcpu, bool evmcs_expected)
 {
 	const bool has_irqchip = !vcpu || vcpu->vm->has_irqchip;
-- 
2.43.0