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[v6,07/14] KVM: arm64: selftests: Add basic support to generate delays

Message ID 20210913230955.156323-8-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, 11:09 p.m. UTC 
Add udelay() support to generate a delay in the guest.

The routines are derived and simplified from kernel's
arch/arm64/lib/delay.c.

Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Reviewed-by: Oliver Upton <oupton@google.com>
---
 .../selftests/kvm/include/aarch64/delay.h     | 25 +++++++++++++++++++
 1 file changed, 25 insertions(+)
 create mode 100644 tools/testing/selftests/kvm/include/aarch64/delay.h
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Patch

diff --git a/tools/testing/selftests/kvm/include/aarch64/delay.h b/tools/testing/selftests/kvm/include/aarch64/delay.h
new file mode 100644
index 000000000000..329e4f5079ea
--- /dev/null
+++ b/tools/testing/selftests/kvm/include/aarch64/delay.h
@@ -0,0 +1,25 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * ARM simple delay routines
+ */
+
+#ifndef SELFTEST_KVM_ARM_DELAY_H
+#define SELFTEST_KVM_ARM_DELAY_H
+
+#include "arch_timer.h"
+
+static inline void __delay(uint64_t cycles)
+{
+	enum arch_timer timer = VIRTUAL;
+	uint64_t start = timer_get_cntct(timer);
+
+	while ((timer_get_cntct(timer) - start) < cycles)
+		cpu_relax();
+}
+
+static inline void udelay(unsigned long usec)
+{
+	__delay(usec_to_cycles(usec));
+}
+
+#endif /* SELFTEST_KVM_ARM_DELAY_H */