[PATCH v3 27/28] KVM: selftests: Define cpu_relax() helpers for s390 and x86

Sean Christopherson
2022-02-26T00:18:19Z

Add cpu_relax() for s390 and x86 for use in arch-agnostic tests. arm64
already defines its own version.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
tools/testing/selftests/kvm/include/s390x/processor.h | 8 ++++++++
tools/testing/selftests/kvm/include/x86_64/processor.h | 5 +++++
2 files changed, 13 insertions(+)

diff --git a/tools/testing/selftests/kvm/include/s390x/processor.h b/tools/testing/selftests/kvm/include/s390x/processor.h
index e0e96a5f608c..255c9b990f4c 100644
--- a/tools/testing/selftests/kvm/include/s390x/processor.h
+++ b/tools/testing/selftests/kvm/include/s390x/processor.h
@@ -5,6 +5,8 @@
#ifndef SELFTEST_KVM_PROCESSOR_H
#define SELFTEST_KVM_PROCESSOR_H

+#include <linux/compiler.h>
+
/* Bits in the region/segment table entry */
#define REGION_ENTRY_ORIGIN ~0xfffUL /* region/segment table origin */
#define REGION_ENTRY_PROTECT 0x200 /* region protection bit */
@@ -19,4 +21,10 @@
#define PAGE_PROTECT 0x200 /* HW read-only bit */
#define PAGE_NOEXEC 0x100 /* HW no-execute bit */

+/* Is there a portable way to do this? */
+static inline void cpu_relax(void)
+{
+ barrier();
+}
+
#endif
diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h
index 8a470da7b71a..37db341d4cc5 100644
--- a/tools/testing/selftests/kvm/include/x86_64/processor.h
+++ b/tools/testing/selftests/kvm/include/x86_64/processor.h
@@ -363,6 +363,11 @@ static inline unsigned long get_xmm(int n)
return 0;
}

+static inline void cpu_relax(void)
+{
+ asm volatile("rep; nop" ::: "memory");
+}
+
bool is_intel_cpu(void);
bool is_amd_cpu(void);

--
2.35.1.574.g5d30c73bfb-goog