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

[Vitaly Kuznetsov]

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

Signed-off-by: Vitaly Kuznetsov <vkuzn...@redhat.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