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[v5,05/14] KVM: arm64: selftests: Add support for cpu_relax

Message ID 20210913204930.130715-6-rananta@google.com (mailing list archive)
State New, archived
Headers show
Series KVM: arm64: selftests: Introduce arch_timer selftest | expand

Commit Message

Raghavendra Rao Ananta Sept. 13, 2021, 8:49 p.m. UTC 
Implement the guest helper routine, cpu_relax(), to yield
the processor to other tasks.

The function was derived from
arch/arm64/include/asm/vdso/processor.h.

Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
Reviewed-by: Oliver Upton <oupton@google.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
---
 tools/testing/selftests/kvm/include/aarch64/processor.h | 5 +++++
 1 file changed, 5 insertions(+)
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Patch

diff --git a/tools/testing/selftests/kvm/include/aarch64/processor.h b/tools/testing/selftests/kvm/include/aarch64/processor.h
index 93797783abad..265054c24481 100644
--- a/tools/testing/selftests/kvm/include/aarch64/processor.h
+++ b/tools/testing/selftests/kvm/include/aarch64/processor.h
@@ -122,6 +122,11 @@  void vm_install_exception_handler(struct kvm_vm *vm,
 void vm_install_sync_handler(struct kvm_vm *vm,
 		int vector, int ec, handler_fn handler);
 
+static inline void cpu_relax(void)
+{
+	asm volatile("yield" ::: "memory");
+}
+
 #define isb()		asm volatile("isb" : : : "memory")
 #define dsb(opt)	asm volatile("dsb " #opt : : : "memory")
 #define dmb(opt)	asm volatile("dmb " #opt : : : "memory")