linux-kernel - [PATCH 3/3] KVM: selftests: hyperv_cpuid: add check for NoNonArchitecturalCoreSharing bit

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Message-Id: <20190916162258.6528-4-vkuznets@redhat.com>
Date:   Mon, 16 Sep 2019 18:22:58 +0200
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     kvm@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, linux-hyperv@...r.kernel.org,
        x86@...nel.org, Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Jim Mattson <jmattson@...gle.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Michael Kelley <mikelley@...rosoft.com>,
        Roman Kagan <rkagan@...tuozzo.com>
Subject: [PATCH 3/3] KVM: selftests: hyperv_cpuid: add check for NoNonArchitecturalCoreSharing bit

The bit is supposed to be '1' when SMT is not supported or forcefully
disabled and '0' otherwise.

Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
---
 .../selftests/kvm/x86_64/hyperv_cpuid.c       | 27 +++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/tools/testing/selftests/kvm/x86_64/hyperv_cpuid.c b/tools/testing/selftests/kvm/x86_64/hyperv_cpuid.c
index ee59831fbc98..443a2b54645b 100644
--- a/tools/testing/selftests/kvm/x86_64/hyperv_cpuid.c
+++ b/tools/testing/selftests/kvm/x86_64/hyperv_cpuid.c
@@ -26,6 +26,25 @@ static void guest_code(void)
 {
 }
 
+static int smt_possible(void)
+{
+	char buf[16];
+	FILE *f;
+	bool res = 1;
+
+	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 = 0;
+		}
+		fclose(f);
+	}
+
+	return res;
+}
+
 static void test_hv_cpuid(struct kvm_cpuid2 *hv_cpuid_entries,
 			  int evmcs_enabled)
 {
@@ -59,6 +78,14 @@ static void test_hv_cpuid(struct kvm_cpuid2 *hv_cpuid_entries,
 		TEST_ASSERT(!entry->padding[0] && !entry->padding[1] &&
 			    !entry->padding[2], "padding should be zero");
 
+		if (entry->function == 0x40000004) {
+			int nononarchcs = !!(entry->eax & (1UL << 18));
+
+			TEST_ASSERT(nononarchcs == !smt_possible(),
+				    "NoNonArchitecturalCoreSharing bit"
+				    " doesn't reflect SMT setting");
+		}
+
 		/*
 		 * If needed for debug:
 		 * fprintf(stdout,
-- 
2.20.1