From: Nicholas Piggin <npiggin@gmail.com>
To: kvm@vger.kernel.org
Cc: Laurent Vivier <lvivier@redhat.com>,
Thomas Huth <thuth@redhat.com>, Nico Boehr <nrb@linux.ibm.com>,
Shaoqin Huang <shahuang@redhat.com>,
Nicholas Piggin <npiggin@gmail.com>,
Andrew Jones <andrew.jones@linux.dev>,
linuxppc-dev@lists.ozlabs.org
Subject: [kvm-unit-tests PATCH v5 27/29] powerpc: Avoid using larx/stcx. in spinlocks when only one CPU is running
Date: Sat, 16 Dec 2023 23:42:54 +1000 [thread overview]
Message-ID: <20231216134257.1743345-28-npiggin@gmail.com> (raw)
In-Reply-To: <20231216134257.1743345-1-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 | 6 ++++++
lib/powerpc/spinlock.c | 28 ++++++++++++++++++++++++++++
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 163bbeec..e2c03295 100644
--- a/lib/powerpc/asm/smp.h
+++ b/lib/powerpc/asm/smp.h
@@ -19,5 +19,6 @@ void local_ipi_disable(void);
void send_ipi(int cpu_id);
extern int nr_cpus_online;
+extern bool multithreaded;
#endif /* _ASMPOWERPC_SMP_H_ */
diff --git a/lib/powerpc/smp.c b/lib/powerpc/smp.c
index 96e3219a..b473ba41 100644
--- a/lib/powerpc/smp.c
+++ b/lib/powerpc/smp.c
@@ -280,6 +280,8 @@ static void start_each_secondary(int fdtnode, u64 regval __unused, void *info)
datap->nr_started += 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
@@ -293,8 +295,10 @@ bool start_all_cpus(secondary_entry_fn entry)
memset(start_secondary_cpus, 0xff, sizeof(start_secondary_cpus));
+ assert(!multithreaded);
assert(nr_cpus_online == 1);
+ multithreaded = true;
nr_started = 0;
nr_cpus_present = 0;
ret = dt_for_each_cpu_node(start_each_secondary, &data);
@@ -305,6 +309,8 @@ bool start_all_cpus(secondary_entry_fn entry)
void stop_all_cpus(void)
{
+ assert(multithreaded);
while (nr_cpus_online > 1)
cpu_relax();
+ multithreaded = false;
}
diff --git a/lib/powerpc/spinlock.c b/lib/powerpc/spinlock.c
new file mode 100644
index 00000000..238549f1
--- /dev/null
+++ b/lib/powerpc/spinlock.c
@@ -0,0 +1,28 @@
+#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 f59eed19..b952386d 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 f9dd937a..caa807f2 100644
--- a/powerpc/Makefile.common
+++ b/powerpc/Makefile.common
@@ -47,6 +47,7 @@ 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
--
2.42.0
next prev parent reply other threads:[~2023-12-16 14:06 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-16 13:42 [kvm-unit-tests PATCH v5 00/29] powerpc: updates, P10, PNV support Nicholas Piggin
2023-12-16 13:42 ` [kvm-unit-tests PATCH v5 01/29] arch-run: Clean up temporary files properly Nicholas Piggin
2023-12-16 13:42 ` [kvm-unit-tests PATCH v5 02/29] arch-run: Clean up initrd cleanup Nicholas Piggin
2023-12-16 13:42 ` [kvm-unit-tests PATCH v5 03/29] migration: use a more robust way to wait for background job Nicholas Piggin
2023-12-16 13:42 ` [kvm-unit-tests PATCH v5 04/29] migration: Support multiple migrations Nicholas Piggin
2023-12-16 13:42 ` [kvm-unit-tests PATCH v5 05/29] arch-run: rename migration variables Nicholas Piggin
2023-12-16 13:42 ` [kvm-unit-tests PATCH v5 06/29] powerpc: Quiet QEMU TCG pseries capability warnings Nicholas Piggin
2023-12-19 5:55 ` Thomas Huth
2023-12-16 13:42 ` [kvm-unit-tests PATCH v5 07/29] powerpc: Add a migration stress tester Nicholas Piggin
2023-12-19 5:58 ` Thomas Huth
2023-12-22 10:32 ` Nicholas Piggin
2023-12-16 13:42 ` [kvm-unit-tests PATCH v5 08/29] powerpc: Require KVM for the TM test Nicholas Piggin
2023-12-19 5:59 ` Thomas Huth
2023-12-16 13:42 ` [kvm-unit-tests PATCH v5 09/29] powerpc: Fix interrupt stack alignment Nicholas Piggin
2023-12-19 6:09 ` Thomas Huth
2023-12-16 13:42 ` [kvm-unit-tests PATCH v5 10/29] powerpc/sprs: Specify SPRs with data rather than code Nicholas Piggin
2023-12-19 6:14 ` Thomas Huth
2023-12-22 10:32 ` Nicholas Piggin
2023-12-16 13:42 ` [kvm-unit-tests PATCH v5 11/29] powerpc/sprs: Don't fail changed SPRs that are used by the test harness Nicholas Piggin
2023-12-19 11:34 ` Thomas Huth
2023-12-16 13:42 ` [kvm-unit-tests PATCH v5 12/29] powerpc/sprs: Avoid taking async interrupts caused by register fuzzing Nicholas Piggin
2023-12-19 11:47 ` Thomas Huth
2023-12-22 9:51 ` Nicholas Piggin
2023-12-16 13:42 ` [kvm-unit-tests PATCH v5 13/29] powerpc: Make interrupt handler error more readable Nicholas Piggin
2023-12-19 11:53 ` Thomas Huth
2023-12-22 9:52 ` Nicholas Piggin
2023-12-16 13:42 ` [kvm-unit-tests PATCH v5 14/29] powerpc: Expand exception handler vector granularity Nicholas Piggin
2023-12-19 11:55 ` Thomas Huth
2023-12-16 13:42 ` [kvm-unit-tests PATCH v5 15/29] powerpc: Add support for more interrupts including HV interrupts Nicholas Piggin
2023-12-16 13:42 ` [kvm-unit-tests PATCH v5 16/29] powerpc: Set .got section alignment to 256 bytes Nicholas Piggin
2023-12-19 12:01 ` Thomas Huth
2023-12-16 13:42 ` [kvm-unit-tests PATCH v5 17/29] powerpc: Discover runtime load address dynamically Nicholas Piggin
2023-12-16 13:42 ` [kvm-unit-tests PATCH v5 18/29] powerpc: Fix stack backtrace termination Nicholas Piggin
2023-12-19 12:22 ` Thomas Huth
2023-12-22 9:55 ` Nicholas Piggin
2023-12-16 13:42 ` [kvm-unit-tests PATCH v5 19/29] scripts: allow machine option to be specified in unittests.cfg Nicholas Piggin
2023-12-19 12:27 ` Thomas Huth
2023-12-16 13:42 ` [kvm-unit-tests PATCH v5 20/29] scripts: Accommodate powerpc powernv machine differences Nicholas Piggin
2023-12-19 12:36 ` Thomas Huth
2023-12-16 13:42 ` [kvm-unit-tests PATCH v5 21/29] powerpc: Support powernv machine with QEMU TCG Nicholas Piggin
2023-12-16 13:42 ` [kvm-unit-tests PATCH v5 22/29] powerpc: Fix emulator illegal instruction test for powernv Nicholas Piggin
2023-12-19 12:39 ` Thomas Huth
2023-12-16 13:42 ` [kvm-unit-tests PATCH v5 23/29] powerpc/sprs: Test hypervisor registers on powernv machine Nicholas Piggin
2023-12-16 13:42 ` [kvm-unit-tests PATCH v5 24/29] powerpc: interrupt tests Nicholas Piggin
2023-12-19 13:57 ` Thomas Huth
2023-12-22 9:58 ` Nicholas Piggin
2023-12-16 13:42 ` [kvm-unit-tests PATCH v5 25/29] powerpc: Add rtas stop-self support Nicholas Piggin
2023-12-19 14:15 ` Thomas Huth
2023-12-16 13:42 ` [kvm-unit-tests PATCH v5 26/29] powerpc: add SMP and IPI support Nicholas Piggin
2023-12-16 13:42 ` Nicholas Piggin [this message]
2023-12-16 13:42 ` [kvm-unit-tests PATCH v5 28/29] powerpc: Add atomics tests Nicholas Piggin
2023-12-16 13:42 ` [kvm-unit-tests PATCH v5 29/29] powerpc: Add timebase tests Nicholas Piggin
2023-12-19 14:23 ` Thomas Huth
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