linux-kernel - [PATCH v5 07/14] KVM: arm64: selftests: Add basic support to generate delays

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Message-Id: <20210913204930.130715-8-rananta@google.com>
Date:   Mon, 13 Sep 2021 20:49:23 +0000
From:   Raghavendra Rao Ananta <rananta@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>, Marc Zyngier <maz@...nel.org>,
        Andrew Jones <drjones@...hat.com>,
        James Morse <james.morse@....com>,
        Alexandru Elisei <alexandru.elisei@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>
Cc:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>, Peter Shier <pshier@...gle.com>,
        Ricardo Koller <ricarkol@...gle.com>,
        Oliver Upton <oupton@...gle.com>,
        Reiji Watanabe <reijiw@...gle.com>,
        Jing Zhang <jingzhangos@...gle.com>,
        Raghavendra Rao Anata <rananta@...gle.com>,
        linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Subject: [PATCH v5 07/14] KVM: arm64: selftests: Add basic support to generate delays

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@...gle.com>
Reviewed-by: Andrew Jones <drjones@...hat.com>
Reviewed-by: Oliver Upton <oupton@...gle.com>
---
 .../selftests/kvm/include/aarch64/delay.h     | 25 +++++++++++++++++++
 1 file changed, 25 insertions(+)
 create mode 100644 tools/testing/selftests/kvm/include/aarch64/delay.h

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 */
-- 
2.33.0.309.g3052b89438-goog