From: Nicholas Piggin <npiggin@gmail.com>
To: Thomas Huth <thuth@redhat.com>
Cc: Laurent Vivier <lvivier@redhat.com>,
kvm@vger.kernel.org, Nicholas Piggin <npiggin@gmail.com>,
Andrew Jones <andrew.jones@linux.dev>,
Paolo Bonzini <pbonzini@redhat.com>,
linuxppc-dev@lists.ozlabs.org
Subject: [kvm-unit-tests PATCH v8 24/35] powerpc: Avoid using larx/stcx. in spinlocks when only one CPU is running
Date: Fri, 5 Apr 2024 18:35:25 +1000 [thread overview]
Message-ID: <20240405083539.374995-25-npiggin@gmail.com> (raw)
In-Reply-To: <20240405083539.374995-1-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 4519e5436..6ef3ae521 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 a3bf85d44..f3b2a3faf 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);
@@ -308,8 +311,10 @@ bool start_all_cpus(secondary_entry_fn entry)
void stop_all_cpus(void)
{
+ assert(multithreaded);
while (nr_cpus_online > 1)
cpu_relax();
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 744dfc1f7..02af54b83 100644
--- a/powerpc/Makefile.common
+++ b/powerpc/Makefile.common
@@ -48,6 +48,7 @@ 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:[~2024-04-05 8:54 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-05 8:35 [kvm-unit-tests PATCH v8 00/35] migration, powerpc improvements Nicholas Piggin
2024-04-05 8:35 ` [kvm-unit-tests PATCH v8 01/35] arch-run: Add functions to help handle migration directives from test Nicholas Piggin
2024-04-05 8:35 ` [kvm-unit-tests PATCH v8 02/35] arch-run: Keep infifo open Nicholas Piggin
2024-04-05 8:35 ` [kvm-unit-tests PATCH v8 03/35] migration: Add a migrate_skip command Nicholas Piggin
2024-04-08 15:59 ` Nico Boehr
2024-04-16 3:22 ` Nicholas Piggin
2024-04-16 4:50 ` Thomas Huth
2024-04-05 8:35 ` [kvm-unit-tests PATCH v8 04/35] (arm|s390): Use migrate_skip in test cases Nicholas Piggin
2024-04-05 13:36 ` Andrew Jones
2024-04-08 15:57 ` Nico Boehr
2024-04-05 8:35 ` [kvm-unit-tests PATCH v8 05/35] arch-run: Add a "continuous" migration option for tests Nicholas Piggin
2024-04-15 14:29 ` Thomas Huth
2024-04-16 4:54 ` Thomas Huth
2024-04-05 8:35 ` [kvm-unit-tests PATCH v8 06/35] gitlab-ci: Run migration selftest on s390x and powerpc Nicholas Piggin
2024-04-08 16:06 ` Nico Boehr
2024-04-11 19:22 ` Thomas Huth
2024-04-16 7:18 ` Thomas Huth
2024-04-16 7:55 ` Thomas Huth
2024-04-16 10:11 ` Thomas Huth
2024-04-05 8:35 ` [kvm-unit-tests PATCH v8 07/35] common: add memory dirtying vs migration test Nicholas Piggin
2024-04-05 8:35 ` [kvm-unit-tests PATCH v8 08/35] powerpc: Fix KVM caps on POWER9 hosts Nicholas Piggin
2024-04-05 8:35 ` [kvm-unit-tests PATCH v8 09/35] powerpc: Fix stack backtrace termination Nicholas Piggin
2024-04-16 7:14 ` Thomas Huth
2024-04-05 8:35 ` [kvm-unit-tests PATCH v8 10/35] powerpc: interrupt stack backtracing Nicholas Piggin
2024-04-16 7:47 ` Thomas Huth
2024-04-05 8:35 ` [kvm-unit-tests PATCH v8 11/35] powerpc/sprs: Specify SPRs with data rather than code Nicholas Piggin
2024-04-16 9:48 ` Thomas Huth
2024-04-05 8:35 ` [kvm-unit-tests PATCH v8 12/35] powerpc/sprs: Avoid taking PMU interrupts caused by register fuzzing Nicholas Piggin
2024-04-05 8:35 ` [kvm-unit-tests PATCH v8 13/35] doc: start documentation directory with unittests.cfg doc Nicholas Piggin
2024-04-05 13:45 ` Andrew Jones
2024-04-08 16:10 ` Nico Boehr
2024-04-05 8:35 ` [kvm-unit-tests PATCH v8 14/35] scripts: allow machine option to be specified in unittests.cfg Nicholas Piggin
2024-04-05 8:35 ` [kvm-unit-tests PATCH v8 15/35] scripts: Accommodate powerpc powernv machine differences Nicholas Piggin
2024-04-05 8:35 ` [kvm-unit-tests PATCH v8 16/35] powerpc: Support powernv machine with QEMU TCG Nicholas Piggin
2024-04-05 8:35 ` [kvm-unit-tests PATCH v8 17/35] powerpc: Fix emulator illegal instruction test for powernv Nicholas Piggin
2024-04-05 8:35 ` [kvm-unit-tests PATCH v8 18/35] powerpc/sprs: Test hypervisor registers on powernv machine Nicholas Piggin
2024-04-05 8:35 ` [kvm-unit-tests PATCH v8 19/35] powerpc: general interrupt tests Nicholas Piggin
2024-04-05 8:35 ` [kvm-unit-tests PATCH v8 20/35] powerpc: Add rtas stop-self support Nicholas Piggin
2024-04-05 8:35 ` [kvm-unit-tests PATCH v8 21/35] powerpc: Remove broken SMP exception stack setup Nicholas Piggin
2024-04-05 8:35 ` [kvm-unit-tests PATCH v8 22/35] powerpc: add SMP and IPI support Nicholas Piggin
2024-04-05 8:35 ` [kvm-unit-tests PATCH v8 23/35] powerpc: Permit ACCEL=tcg,thread=single Nicholas Piggin
2024-04-05 8:35 ` Nicholas Piggin [this message]
2024-04-05 8:35 ` [kvm-unit-tests PATCH v8 25/35] powerpc: Add atomics tests Nicholas Piggin
2024-04-05 8:35 ` [kvm-unit-tests PATCH v8 26/35] powerpc: Add timebase tests Nicholas Piggin
2024-04-05 8:35 ` [kvm-unit-tests PATCH v8 27/35] powerpc: Add MMU support Nicholas Piggin
2024-04-05 8:35 ` [kvm-unit-tests PATCH v8 28/35] common/sieve: Use vmalloc.h for setup_mmu definition Nicholas Piggin
2024-04-05 8:35 ` [kvm-unit-tests PATCH v8 29/35] common/sieve: Support machines without MMU Nicholas Piggin
2024-04-05 8:35 ` [kvm-unit-tests PATCH v8 30/35] powerpc: Add sieve.c common test Nicholas Piggin
2024-04-05 8:35 ` [kvm-unit-tests PATCH v8 31/35] powerpc: add usermode support Nicholas Piggin
2024-04-05 8:35 ` [kvm-unit-tests PATCH v8 32/35] powerpc: add pmu tests Nicholas Piggin
2024-04-05 8:35 ` [kvm-unit-tests PATCH v8 33/35] configure: Make arch_libdir a first-class entity Nicholas Piggin
2024-04-05 8:35 ` [kvm-unit-tests PATCH v8 34/35] powerpc: Remove remnants of ppc64 directory and build structure Nicholas Piggin
2024-04-05 8:35 ` [kvm-unit-tests PATCH v8 35/35] powerpc: gitlab CI update Nicholas Piggin
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