[kvm-unit-tests PATCH v3 15/20] x86/kvmclock: Skip kvmclock test when not running on KVM with CLOCKSOURCE2

[Sean Christopherson <seanjc@google.com>]

Skip the kvmclock test if the (virtual) CPU isn't running on KVM and/or
doesn't have CLOCKSOURCE2.  Presumably non-KVM environments simply don't
run the test, but checking for kvmclock support is easy enough.  E.g. with

  -cpu host,-kvmclock,kvm-pv-enforce-cpuid

the test will die on WRMSR #GPs without the checks, but generate

  SKIP: CPU not running on KVM with CLOCKSOURCE2
  SUMMARY: 1 tests, 1 skipped

with the appropriate checks.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 lib/x86/processor.h | 15 +++++++++++++++
 x86/kvmclock.h      |  2 ++
 x86/kvmclock_test.c |  9 ++++++++-
 3 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/lib/x86/processor.h b/lib/x86/processor.h
index 32ce08e2..ba7065f7 100644
--- a/lib/x86/processor.h
+++ b/lib/x86/processor.h
@@ -317,6 +317,7 @@ struct x86_cpu_feature {
 #define X86_FEATURE_XSAVE		X86_CPU_FEATURE(0x1, 0, ECX, 26)
 #define X86_FEATURE_OSXSAVE		X86_CPU_FEATURE(0x1, 0, ECX, 27)
 #define X86_FEATURE_RDRAND		X86_CPU_FEATURE(0x1, 0, ECX, 30)
+#define X86_FEATURE_HYPERVISOR		X86_CPU_FEATURE(0x1, 0, ECX, 31)
 #define X86_FEATURE_MCE			X86_CPU_FEATURE(0x1, 0, EDX, 7)
 #define X86_FEATURE_APIC		X86_CPU_FEATURE(0x1, 0, EDX, 9)
 #define X86_FEATURE_CLFLUSH		X86_CPU_FEATURE(0x1, 0, EDX, 19)
@@ -351,6 +352,7 @@ struct x86_cpu_feature {
 /*
  * KVM defined leafs
  */
+#define KVM_FEATURE_CLOCKSOURCE2	X86_CPU_FEATURE(0x40000001, 0, EAX, 3)
 #define KVM_FEATURE_ASYNC_PF		X86_CPU_FEATURE(0x40000001, 0, EAX, 4)
 #define KVM_FEATURE_ASYNC_PF_INT	X86_CPU_FEATURE(0x40000001, 0, EAX, 14)
 
@@ -449,6 +451,7 @@ struct x86_cpu_property {
 #define X86_PROPERTY_AMX_NR_TILE_REGS		X86_CPU_PROPERTY(0x1d, 1, EBX, 16, 31)
 #define X86_PROPERTY_AMX_MAX_ROWS		X86_CPU_PROPERTY(0x1d, 1, ECX, 0,  15)
 
+#define KVM_SIGNATURE "KVMKVMKVM\0\0\0"
 #define X86_PROPERTY_MAX_KVM_LEAF		X86_CPU_PROPERTY(0x40000000, 0, EAX, 0, 31)
 
 #define X86_PROPERTY_MAX_EXT_LEAF		X86_CPU_PROPERTY(0x80000000, 0, EAX, 0, 31)
@@ -506,6 +509,18 @@ static __always_inline bool this_cpu_has_p(struct x86_cpu_property property)
 	return max_leaf >= property.function;
 }
 
+static inline bool this_cpu_has_kvm(void)
+{
+	struct cpuid signature;
+
+	if (!this_cpu_has(X86_FEATURE_HYPERVISOR) ||
+	    !this_cpu_has_p(X86_PROPERTY_MAX_KVM_LEAF))
+		return false;
+
+	signature = cpuid(X86_PROPERTY_MAX_KVM_LEAF.function);
+	return !memcmp(KVM_SIGNATURE, &signature.b, 12);
+}
+
 static inline u8 cpuid_maxphyaddr(void)
 {
 	if (!this_cpu_has_p(X86_PROPERTY_MAX_PHY_ADDR))
diff --git a/x86/kvmclock.h b/x86/kvmclock.h
index 1a40a7c0..bde9a21f 100644
--- a/x86/kvmclock.h
+++ b/x86/kvmclock.h
@@ -1,6 +1,8 @@
 #ifndef X86_KVMCLOCK_H
 #define X86_KVMCLOCK_H
 
+#include "libcflat.h"
+
 #define MSR_KVM_WALL_CLOCK_NEW  0x4b564d00
 #define MSR_KVM_SYSTEM_TIME_NEW 0x4b564d01
 
diff --git a/x86/kvmclock_test.c b/x86/kvmclock_test.c
index d21c6c72..659be870 100644
--- a/x86/kvmclock_test.c
+++ b/x86/kvmclock_test.c
@@ -108,6 +108,11 @@ int main(int ac, char **av)
 	int ncpus;
 	int i;
 
+	if (!this_cpu_has_kvm() || !this_cpu_has(KVM_FEATURE_CLOCKSOURCE2)) {
+		report_skip("CPU not running on KVM with CLOCKSOURCE2");
+		goto out;
+	}
+
 	if (ac > 1)
 		loops = atol(av[1]);
 	if (ac > 2)
@@ -151,5 +156,7 @@ int main(int ac, char **av)
 
 	on_cpus(kvm_clock_clear, NULL);
 
-	return nerr > 0 ? 1 : 0;
+	report(!nerr, "%u time warps detected", nerr);
+out:
+	return report_summary();
 }
-- 
2.54.0.563.g4f69b47b94-goog