From: Nicholas Piggin <npiggin@gmail.com>
To: Thomas Huth <thuth@redhat.com>
Cc: Nicholas Piggin <npiggin@gmail.com>,
Laurent Vivier <lvivier@redhat.com>,
Andrew Jones <andrew.jones@linux.dev>,
linuxppc-dev@lists.ozlabs.org, kvm@vger.kernel.org
Subject: [kvm-unit-tests PATCH v9 19/31] powerpc: Avoid using larx/stcx. in spinlocks when only one CPU is running
Date: Sat, 4 May 2024 22:28:25 +1000 [thread overview]
Message-ID: <20240504122841.1177683-20-npiggin@gmail.com> (raw)
In-Reply-To: <20240504122841.1177683-1-npiggin@gmail.com>
The test harness uses spinlocks if they are implemented with larx/stcx.
it can prevent some test scenarios such as testing migration of a
reservation.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
lib/powerpc/asm/smp.h | 1 +
lib/powerpc/smp.c | 5 +++++
lib/powerpc/spinlock.c | 29 +++++++++++++++++++++++++++++
lib/ppc64/asm/spinlock.h | 7 ++++++-
powerpc/Makefile.common | 1 +
5 files changed, 42 insertions(+), 1 deletion(-)
create mode 100644 lib/powerpc/spinlock.c
diff --git a/lib/powerpc/asm/smp.h b/lib/powerpc/asm/smp.h
index c45988bfa..66188b9dd 100644
--- a/lib/powerpc/asm/smp.h
+++ b/lib/powerpc/asm/smp.h
@@ -15,6 +15,7 @@ struct cpu {
extern int nr_cpus_present;
extern int nr_cpus_online;
+extern bool multithreaded;
extern struct cpu cpus[];
register struct cpu *__current_cpu asm("r13");
diff --git a/lib/powerpc/smp.c b/lib/powerpc/smp.c
index 27b169841..73c0ef214 100644
--- a/lib/powerpc/smp.c
+++ b/lib/powerpc/smp.c
@@ -276,6 +276,8 @@ static void start_each_secondary(int fdtnode, u64 regval __unused, void *info)
start_core(fdtnode, datap->entry);
}
+bool multithreaded = false;
+
/*
* Start all stopped cpus on the guest at entry with register 3 set to r3
* We expect that we come in with only one thread currently started
@@ -290,6 +292,7 @@ bool start_all_cpus(secondary_entry_fn entry)
assert(nr_cpus_online == 1);
assert(nr_started == 1);
+ multithreaded = true;
ret = dt_for_each_cpu_node(start_each_secondary, &data);
assert(ret == 0);
assert(nr_started == nr_cpus_present);
@@ -361,10 +364,12 @@ static void wait_each_secondary(int fdtnode, u64 regval __unused, void *info)
void stop_all_cpus(void)
{
+ assert(multithreaded);
while (nr_cpus_online > 1)
cpu_relax();
dt_for_each_cpu_node(wait_each_secondary, NULL);
mb();
nr_started = 1;
+ multithreaded = false;
}
diff --git a/lib/powerpc/spinlock.c b/lib/powerpc/spinlock.c
new file mode 100644
index 000000000..623a1f2c1
--- /dev/null
+++ b/lib/powerpc/spinlock.c
@@ -0,0 +1,29 @@
+/* SPDX-License-Identifier: LGPL-2.0 */
+#include <asm/spinlock.h>
+#include <asm/smp.h>
+
+/*
+ * Skip the atomic when single-threaded, which helps avoid larx/stcx. in
+ * the harness when testing tricky larx/stcx. sequences (e.g., migration
+ * vs reservation).
+ */
+void spin_lock(struct spinlock *lock)
+{
+ if (!multithreaded) {
+ assert(lock->v == 0);
+ lock->v = 1;
+ } else {
+ while (__sync_lock_test_and_set(&lock->v, 1))
+ ;
+ }
+}
+
+void spin_unlock(struct spinlock *lock)
+{
+ assert(lock->v == 1);
+ if (!multithreaded) {
+ lock->v = 0;
+ } else {
+ __sync_lock_release(&lock->v);
+ }
+}
diff --git a/lib/ppc64/asm/spinlock.h b/lib/ppc64/asm/spinlock.h
index f59eed191..b952386da 100644
--- a/lib/ppc64/asm/spinlock.h
+++ b/lib/ppc64/asm/spinlock.h
@@ -1,6 +1,11 @@
#ifndef _ASMPPC64_SPINLOCK_H_
#define _ASMPPC64_SPINLOCK_H_
-#include <asm-generic/spinlock.h>
+struct spinlock {
+ unsigned int v;
+};
+
+void spin_lock(struct spinlock *lock);
+void spin_unlock(struct spinlock *lock);
#endif /* _ASMPPC64_SPINLOCK_H_ */
diff --git a/powerpc/Makefile.common b/powerpc/Makefile.common
index b98f71c2f..1ee9c25d6 100644
--- a/powerpc/Makefile.common
+++ b/powerpc/Makefile.common
@@ -49,6 +49,7 @@ cflatobjs += lib/powerpc/rtas.o
cflatobjs += lib/powerpc/processor.o
cflatobjs += lib/powerpc/handlers.o
cflatobjs += lib/powerpc/smp.o
+cflatobjs += lib/powerpc/spinlock.o
OBJDIRS += lib/powerpc
--
2.43.0
next prev parent reply other threads:[~2024-05-04 12:30 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-04 12:28 [kvm-unit-tests PATCH v9 00/31] powerpc improvements Nicholas Piggin
2024-05-04 12:28 ` [kvm-unit-tests PATCH v9 01/31] doc: update unittests doc Nicholas Piggin
2024-05-06 7:03 ` Thomas Huth
2024-05-07 3:57 ` Nicholas Piggin
2024-05-06 8:02 ` Andrew Jones
2024-05-04 12:28 ` [kvm-unit-tests PATCH v9 02/31] report: Add known failure reporting option Nicholas Piggin
2024-05-06 7:25 ` Thomas Huth
2024-05-06 8:01 ` Andrew Jones
2024-05-06 10:19 ` Thomas Huth
2024-05-04 12:28 ` [kvm-unit-tests PATCH v9 03/31] powerpc: Mark known failing tests as kfail Nicholas Piggin
2024-05-06 7:37 ` Thomas Huth
2024-05-07 4:07 ` Nicholas Piggin
2024-05-07 11:44 ` Thomas Huth
2024-05-04 12:28 ` [kvm-unit-tests PATCH v9 04/31] powerpc: Update unittests for latest QEMU version Nicholas Piggin
2024-05-04 12:28 ` [kvm-unit-tests PATCH v9 05/31] powerpc/sprs: Specify SPRs with data rather than code Nicholas Piggin
2024-05-04 12:28 ` [kvm-unit-tests PATCH v9 06/31] powerpc/sprs: Avoid taking PMU interrupts caused by register fuzzing Nicholas Piggin
2024-05-04 12:28 ` [kvm-unit-tests PATCH v9 07/31] scripts: allow machine option to be specified in unittests.cfg Nicholas Piggin
2024-05-07 15:08 ` Thomas Huth
2024-05-08 12:27 ` Nicholas Piggin
2024-05-08 12:55 ` Thomas Huth
2024-05-08 12:58 ` Thomas Huth
2024-05-08 13:36 ` Thomas Huth
2024-05-09 5:44 ` Nicholas Piggin
2024-05-04 12:28 ` [kvm-unit-tests PATCH v9 08/31] scripts: Accommodate powerpc powernv machine differences Nicholas Piggin
2024-05-04 12:28 ` [kvm-unit-tests PATCH v9 09/31] powerpc: Support powernv machine with QEMU TCG Nicholas Piggin
2024-05-04 12:28 ` [kvm-unit-tests PATCH v9 10/31] powerpc: Fix emulator illegal instruction test for powernv Nicholas Piggin
2024-05-04 12:28 ` [kvm-unit-tests PATCH v9 11/31] powerpc/sprs: Test hypervisor registers on powernv machine Nicholas Piggin
2024-05-04 12:28 ` [kvm-unit-tests PATCH v9 12/31] powerpc: general interrupt tests Nicholas Piggin
2024-05-07 12:12 ` Thomas Huth
2024-05-04 12:28 ` [kvm-unit-tests PATCH v9 13/31] powerpc: Add rtas stop-self support Nicholas Piggin
2024-05-04 12:28 ` [kvm-unit-tests PATCH v9 14/31] powerpc: Remove broken SMP exception stack setup Nicholas Piggin
2024-05-04 12:28 ` [kvm-unit-tests PATCH v9 15/31] powerpc: Enable page alloc operations Nicholas Piggin
2024-05-04 12:28 ` [kvm-unit-tests PATCH v9 16/31] powerpc: add SMP and IPI support Nicholas Piggin
2024-05-04 12:28 ` [kvm-unit-tests PATCH v9 17/31] powerpc: Add cpu_relax Nicholas Piggin
2024-05-07 13:44 ` Thomas Huth
2024-05-04 12:28 ` [kvm-unit-tests PATCH v9 18/31] powerpc: Permit ACCEL=tcg,thread=single Nicholas Piggin
2024-05-04 12:28 ` Nicholas Piggin [this message]
2024-05-04 12:28 ` [kvm-unit-tests PATCH v9 20/31] powerpc: Add atomics tests Nicholas Piggin
2024-05-04 12:28 ` [kvm-unit-tests PATCH v9 21/31] powerpc: Add timebase tests Nicholas Piggin
2024-05-04 12:28 ` [kvm-unit-tests PATCH v9 22/31] powerpc: Add MMU support Nicholas Piggin
2024-05-04 12:28 ` [kvm-unit-tests PATCH v9 23/31] common/sieve: Use vmalloc.h for setup_mmu definition Nicholas Piggin
2024-05-04 12:28 ` [kvm-unit-tests PATCH v9 24/31] common/sieve: Support machines without MMU Nicholas Piggin
2024-05-04 12:28 ` [kvm-unit-tests PATCH v9 25/31] powerpc: Add sieve.c common test Nicholas Piggin
2024-05-04 12:28 ` [kvm-unit-tests PATCH v9 26/31] powerpc: add usermode support Nicholas Piggin
2024-05-04 12:28 ` [kvm-unit-tests PATCH v9 27/31] powerpc: add pmu tests Nicholas Piggin
2024-05-04 12:28 ` [kvm-unit-tests PATCH v9 28/31] configure: Make arch_libdir a first-class entity Nicholas Piggin
2024-05-04 12:28 ` [kvm-unit-tests PATCH v9 29/31] powerpc: Remove remnants of ppc64 directory and build structure Nicholas Piggin
2024-05-04 12:28 ` [kvm-unit-tests PATCH v9 30/31] powerpc: Add facility to query TCG or KVM host Nicholas Piggin
2024-05-04 12:28 ` [kvm-unit-tests PATCH v9 31/31] powerpc: gitlab CI update Nicholas Piggin
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