KVM: arm64: selftests: Add light-weight spinlock support

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>
Reviewed-by: Oliver Upton <oupton@google.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211007233439.1826892-12-rananta@google.com

diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index d1774f4613939702723d6f898915c05484bd5d1b..d8fb91a5ea7be1b6155f174f46ab621857714689 100644 (file)
--- 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 (file)
index 0000000..cf09841
--- /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 (file)
index 0000000..a076e78
--- /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)
+{
+       int 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");
+}