[PATCH 08/10] KVM: arm64: selftests: Add light-weight spinlock support

From: Raghavendra Rao Ananta <rananta@google.com>
To: Paolo Bonzini <pbonzini@redhat.com>, Marc Zyngier <maz@kernel.org>
Cc: Alexandru Elisei <alexandru.elisei@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	James Morse <james.morse@arm.com>,
	Peter Shier <pshier@google.com>,
	Ricardo Koller <ricarkol@google.com>,
	Oliver Upton <oupton@google.com>,
	Reiji Watanabe <reijiw@google.com>,
	Jing Zhang <jingzhangos@google.com>,
	Raghavendra Rao Anata <rananta@google.com>,
	kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu
Subject: [PATCH 08/10] KVM: arm64: selftests: Add light-weight spinlock support
Date: Fri, 13 Aug 2021 21:12:09 +0000	[thread overview]
Message-ID: <20210813211211.2983293-9-rananta@google.com> (raw)
In-Reply-To: <20210813211211.2983293-1-rananta@google.com>

Add a simpler version of spinlock support for ARM64 for
the guests to use.

The implementation is loosely based on the spinlock
implementation in kvm-unit-tests.

Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
---
 tools/testing/selftests/kvm/Makefile          |  2 +-
 .../selftests/kvm/include/aarch64/spinlock.h  | 13 +++++++++
 .../selftests/kvm/lib/aarch64/spinlock.c      | 27 +++++++++++++++++++
 3 files changed, 41 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/kvm/include/aarch64/spinlock.h
 create mode 100644 tools/testing/selftests/kvm/lib/aarch64/spinlock.c

diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index 5832f510a16c..8f6d82b570bd 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -35,7 +35,7 @@ endif
 
 LIBKVM = lib/assert.c lib/elf.c lib/io.c lib/kvm_util.c lib/rbtree.c lib/sparsebit.c lib/test_util.c lib/guest_modes.c lib/perf_test_util.c
 LIBKVM_x86_64 = lib/x86_64/apic.c lib/x86_64/processor.c lib/x86_64/vmx.c lib/x86_64/svm.c lib/x86_64/ucall.c lib/x86_64/handlers.S
-LIBKVM_aarch64 = lib/aarch64/processor.c lib/aarch64/ucall.c lib/aarch64/handlers.S
+LIBKVM_aarch64 = lib/aarch64/processor.c lib/aarch64/ucall.c lib/aarch64/handlers.S lib/aarch64/spinlock.c
 LIBKVM_s390x = lib/s390x/processor.c lib/s390x/ucall.c lib/s390x/diag318_test_handler.c
 
 TEST_GEN_PROGS_x86_64 = x86_64/cr4_cpuid_sync_test
diff --git a/tools/testing/selftests/kvm/include/aarch64/spinlock.h b/tools/testing/selftests/kvm/include/aarch64/spinlock.h
new file mode 100644
index 000000000000..cf0984106d14
--- /dev/null
+++ b/tools/testing/selftests/kvm/include/aarch64/spinlock.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef SELFTEST_KVM_ARM64_SPINLOCK_H
+#define SELFTEST_KVM_ARM64_SPINLOCK_H
+
+struct spinlock {
+	int v;
+};
+
+extern void spin_lock(struct spinlock *lock);
+extern void spin_unlock(struct spinlock *lock);
+
+#endif /* SELFTEST_KVM_ARM64_SPINLOCK_H */
diff --git a/tools/testing/selftests/kvm/lib/aarch64/spinlock.c b/tools/testing/selftests/kvm/lib/aarch64/spinlock.c
new file mode 100644
index 000000000000..6d66a3dac237
--- /dev/null
+++ b/tools/testing/selftests/kvm/lib/aarch64/spinlock.c
@@ -0,0 +1,27 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ARM64 Spinlock support
+ */
+#include <stdint.h>
+
+#include "spinlock.h"
+
+void spin_lock(struct spinlock *lock)
+{
+	uint32_t val, res;
+
+	asm volatile(
+	"1:	ldaxr	%w0, [%2]\n"
+	"	cbnz	%w0, 1b\n"
+	"	mov	%w0, #1\n"
+	"	stxr	%w1, %w0, [%2]\n"
+	"	cbnz	%w1, 1b\n"
+	: "=&r" (val), "=&r" (res)
+	: "r" (&lock->v)
+	: "memory");
+}
+
+void spin_unlock(struct spinlock *lock)
+{
+	asm volatile("stlr wzr, [%0]\n"	: : "r" (&lock->v) : "memory");
+}
-- 
2.33.0.rc1.237.g0d66db33f3-goog

