[PATCH v2 4/5] selftests: kvm: use a helper function for reading cpuid

[Oliver Upton <oupton@xxxxxxxxxx>]

Derived from kvm-unit-tests.

Reviewed-by: Jim Mattson <jmattson@xxxxxxxxxx>
Reviewed-by: Peter Shier <pshier@xxxxxxxxxx>
Signed-off-by: Oliver Upton <oupton@xxxxxxxxxx>
---
 .../selftests/kvm/include/x86_64/processor.h      | 15 +++++++++++++++
 .../selftests/kvm/include/x86_64/svm_util.h       |  7 ++-----
 2 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h
index 82b7fe16a824..316fbd4700ef 100644
--- a/tools/testing/selftests/kvm/include/x86_64/processor.h
+++ b/tools/testing/selftests/kvm/include/x86_64/processor.h
@@ -338,6 +338,21 @@ uint32_t kvm_get_cpuid_max_basic(void);
 uint32_t kvm_get_cpuid_max_extended(void);
 void kvm_get_cpu_address_width(unsigned int *pa_bits, unsigned int *va_bits);
 
+struct cpuid {
+	u32 a, b, c, d;
+};
+
+static inline struct cpuid raw_cpuid(u32 function, u32 index)
+{
+	struct cpuid r;
+
+	asm volatile("cpuid"
+		     : "=a"(r.a), "=b"(r.b), "=c"(r.c), "=d"(r.d)
+		     : "0"(function), "2"(index));
+
+	return r;
+}
+
 /*
  * Basic CPU control in CR0
  */
diff --git a/tools/testing/selftests/kvm/include/x86_64/svm_util.h b/tools/testing/selftests/kvm/include/x86_64/svm_util.h
index b7531c83b8ae..47a13aaee460 100644
--- a/tools/testing/selftests/kvm/include/x86_64/svm_util.h
+++ b/tools/testing/selftests/kvm/include/x86_64/svm_util.h
@@ -38,12 +38,9 @@ void nested_svm_check_supported(void);
 
 static inline bool cpu_has_svm(void)
 {
-	u32 eax = 0x80000001, ecx;
+	struct cpuid r = raw_cpuid(0x80000001, 0);
 
-	asm("cpuid" :
-	    "=a" (eax), "=c" (ecx) : "0" (eax) : "ebx", "edx");
-
-	return ecx & CPUID_SVM;
+	return r.c & CPUID_SVM;
 }
 
 #endif /* SELFTEST_KVM_SVM_UTILS_H */
-- 
2.28.0.rc0.142.g3c755180ce-goog