Re: [PATCH] perf: arm_cspmu: Separate Arm and vendor module

From: Suzuki K Poulose
Date: Tue Apr 04 2023 - 06:08:50 EST

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In reply to: Besar Wicaksono: "[PATCH] perf: arm_cspmu: Separate Arm and vendor module"
Next in thread: Besar Wicaksono: "RE: [PATCH] perf: arm_cspmu: Separate Arm and vendor module"
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Hi Besar

On 03/04/2023 17:39, Besar Wicaksono wrote:

Arm Coresight PMU driver consists of main standard code and vendor
backend code. Both are currently built as a single module.
This patch adds vendor registration API to separate the two to
keep things modular. Vendor module shall register to the main
module on loading and trigger device reprobe.

Thanks for working on this.

Signed-off-by: Besar Wicaksono <bwicaksono@xxxxxxxxxx>
---
drivers/perf/arm_cspmu/Makefile | 3 +-
drivers/perf/arm_cspmu/arm_cspmu.c | 113 +++++++++++++++++++++-----
drivers/perf/arm_cspmu/arm_cspmu.h | 10 ++-
drivers/perf/arm_cspmu/nvidia_cspmu.c | 24 +++++-
drivers/perf/arm_cspmu/nvidia_cspmu.h | 17 ----
5 files changed, 124 insertions(+), 43 deletions(-)
delete mode 100644 drivers/perf/arm_cspmu/nvidia_cspmu.h

diff --git a/drivers/perf/arm_cspmu/Makefile b/drivers/perf/arm_cspmu/Makefile
index fedb17df982d..2514ad34aaf0 100644
--- a/drivers/perf/arm_cspmu/Makefile
+++ b/drivers/perf/arm_cspmu/Makefile
@@ -2,5 +2,4 @@
#
# SPDX-License-Identifier: GPL-2.0
-obj-$(CONFIG_ARM_CORESIGHT_PMU_ARCH_SYSTEM_PMU) += arm_cspmu_module.o
-arm_cspmu_module-y := arm_cspmu.o nvidia_cspmu.o
+obj-$(CONFIG_ARM_CORESIGHT_PMU_ARCH_SYSTEM_PMU) += arm_cspmu.o nvidia_cspmu.o

Now that we have a mechanism to add the NVIDIA CSPMU driver, please could we make it a separate Kconfig ?

diff --git a/drivers/perf/arm_cspmu/arm_cspmu.c b/drivers/perf/arm_cspmu/arm_cspmu.c
index e31302ab7e37..6dbcd46d9fdf 100644
--- a/drivers/perf/arm_cspmu/arm_cspmu.c
+++ b/drivers/perf/arm_cspmu/arm_cspmu.c
@@ -16,7 +16,7 @@
* The user should refer to the vendor technical documentation to get details
* about the supported events.
*
- * Copyright (c) 2022, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+ * Copyright (c) 2022-2023, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
*
*/
@@ -25,13 +25,13 @@
#include <linux/ctype.h>
#include <linux/interrupt.h>
#include <linux/io-64-nonatomic-lo-hi.h>
+#include <linux/list.h>
#include <linux/module.h>
#include <linux/perf_event.h>
#include <linux/platform_device.h>
#include <acpi/processor.h>
#include "arm_cspmu.h"
-#include "nvidia_cspmu.h"
#define PMUNAME "arm_cspmu"
#define DRVNAME "arm-cs-arch-pmu"
@@ -117,11 +117,14 @@
*/
#define HILOHI_MAX_POLL 1000
-/* JEDEC-assigned JEP106 identification code */
-#define ARM_CSPMU_IMPL_ID_NVIDIA 0x36B
-
static unsigned long arm_cspmu_cpuhp_state;
+/* List of Coresight PMU instances in the system. */
+static LIST_HEAD(cspmus);
+
+/* List of registered vendor backends. */
+static LIST_HEAD(cspmu_impls);
+
/*
* In CoreSight PMU architecture, all of the MMIO registers are 32-bit except
* counter register. The counter register can be implemented as 32-bit or 64-bit
@@ -380,26 +383,94 @@ static struct attribute_group arm_cspmu_cpumask_attr_group = {
};
struct impl_match {
- u32 pmiidr;
- u32 mask;
+ struct list_head next;
+ u32 pmiidr_impl;

Do we need something more flexible here ? i.e.,

u32 pmiidr_val;
u32 pmiidr_mask;

So that, a single backend could support multiple/reduced
set of devices.

int (*impl_init_ops)(struct arm_cspmu *cspmu); > };
-static const struct impl_match impl_match[] = {
- {
- .pmiidr = ARM_CSPMU_IMPL_ID_NVIDIA,
- .mask = ARM_CSPMU_PMIIDR_IMPLEMENTER,
- .impl_init_ops = nv_cspmu_init_ops
- },
- {}
-};
+static struct impl_match *arm_cspmu_get_impl_match(u32 pmiidr_impl)
+{
+ struct impl_match *impl_match;
+
+ list_for_each_entry(impl_match, &cspmu_impls, next) {
+ if (impl_match->pmiidr_impl == pmiidr_impl)

And this could be:
((pmiidr_impl & impl_match->pmiidr_mask) == match->pmiidr_val)

+ return impl_match;
+ }
+
+ return NULL;
+}
+
+static int arm_cspmu_device_reprobe(u32 pmiidr_impl)
+{
+ int ret;
+ struct arm_cspmu *cspmu, *temp;
+
+ /* Reprobe all arm_cspmu devices associated with implementer id. */
+ list_for_each_entry_safe(cspmu, temp, &cspmus, next) {
+ const u32 impl_id = FIELD_GET(ARM_CSPMU_PMIIDR_IMPLEMENTER,
+ cspmu->impl.pmiidr);
+
+ if (pmiidr_impl == impl_id) {
+ ret = device_reprobe(cspmu->dev);
+ if (ret) {
+ dev_err(cspmu->dev, "Failed reprobe %s\n",
+ cspmu->name);
+ return ret;
+ }

break here ?

+ }
+ }
+
+ return 0;
+}
+
+int arm_cspmu_impl_register(u32 pmiidr_impl,
+ int (*impl_init_ops)(struct arm_cspmu *cspmu))
+{
+ struct impl_match *impl;
+
+ if (arm_cspmu_get_impl_match(pmiidr_impl)) {
+ pr_err("ARM CSPMU implementer: 0x%x is already registered\n",
+ pmiidr_impl);
+ return -EEXIST;
+ }
+
+ impl = kzalloc(sizeof(struct impl_match), GFP_KERNEL);
+
+ list_add(&impl->next, &cspmu_impls);

Don't we need a lock protect this one ?

+
+ impl->pmiidr_impl = pmiidr_impl;
+ impl->impl_init_ops = impl_init_ops;

Would be good to do these steps before we actually add it to the
list. Anyways, the lock is still needed to prevent races.

+
+ return arm_cspmu_device_reprobe(pmiidr_impl);
+}
+EXPORT_SYMBOL_GPL(arm_cspmu_impl_register);
+
+void arm_cspmu_impl_unregister(u32 pmiidr_impl)
+{
+ struct impl_match *impl;
+
+ impl = arm_cspmu_get_impl_match(pmiidr_impl);
+ if (!impl) {
+ pr_err("Unable to find ARM CSPMU implementer: 0x%x\n",
+ pmiidr_impl);
+ return;
+ }
+
+ list_del(&impl->next);
+ kfree(impl);
+
+ if (arm_cspmu_device_reprobe(pmiidr_impl))
+ pr_err("ARM CSPMU failed reprobe implementer: 0x%x\n",
+ pmiidr_impl);

Is this for falling back to the generic driver ?

+}
+EXPORT_SYMBOL_GPL(arm_cspmu_impl_unregister);
static int arm_cspmu_init_impl_ops(struct arm_cspmu *cspmu)
{
int ret;
struct acpi_apmt_node *apmt_node = cspmu->apmt_node;
struct arm_cspmu_impl_ops *impl_ops = &cspmu->impl.ops;
- const struct impl_match *match = impl_match;
+ const struct impl_match *match;
/*
* Get PMU implementer and product id from APMT node.
@@ -411,10 +482,11 @@ static int arm_cspmu_init_impl_ops(struct arm_cspmu *cspmu)
readl(cspmu->base0 + PMIIDR);
/* Find implementer specific attribute ops. */
- for (; match->pmiidr; match++) {
- const u32 mask = match->mask;
+ list_for_each_entry(match, &cspmu_impls, next) {
+ const u32 impl_id = FIELD_GET(ARM_CSPMU_PMIIDR_IMPLEMENTER,
+ cspmu->impl.pmiidr);
- if ((match->pmiidr & mask) == (cspmu->impl.pmiidr & mask)) {
+ if (match->pmiidr_impl == impl_id) {

match = arm_cspmu_get_impl_match(); ?

ret = match->impl_init_ops(cspmu);
if (ret)
return ret;
@@ -924,6 +996,8 @@ static struct arm_cspmu *arm_cspmu_alloc(struct platform_device *pdev)
if (!cspmu)
return NULL;
+ list_add(&cspmu->next, &cspmus);
+
cspmu->dev = dev;
cspmu->apmt_node = apmt_node;
@@ -1214,6 +1288,7 @@ static int arm_cspmu_device_remove(struct platform_device *pdev)
perf_pmu_unregister(&cspmu->pmu);
cpuhp_state_remove_instance(arm_cspmu_cpuhp_state, &cspmu->cpuhp_node);
+ list_del(&cspmu->next);
return 0;
}
diff --git a/drivers/perf/arm_cspmu/arm_cspmu.h b/drivers/perf/arm_cspmu/arm_cspmu.h
index 51323b175a4a..64c3b565f1b1 100644
--- a/drivers/perf/arm_cspmu/arm_cspmu.h
+++ b/drivers/perf/arm_cspmu/arm_cspmu.h
@@ -1,7 +1,7 @@
/* SPDX-License-Identifier: GPL-2.0
*
* ARM CoreSight Architecture PMU driver.
- * Copyright (c) 2022, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+ * Copyright (c) 2022-2023, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
*
*/
@@ -116,6 +116,7 @@ struct arm_cspmu_impl {
/* Coresight PMU descriptor. */
struct arm_cspmu {
+ struct list_head next;
struct pmu pmu;
struct device *dev;
struct acpi_apmt_node *apmt_node;
@@ -148,4 +149,11 @@ ssize_t arm_cspmu_sysfs_format_show(struct device *dev,
struct device_attribute *attr,
char *buf);
+/* Register vendor backend. */
+int arm_cspmu_impl_register(u32 pmiidr_impl,
+ int (*impl_init_ops)(struct arm_cspmu *cspmu));

May be pack it in the structure ?

Suzuki

+
+/* Unregister vendor backend. */
+void arm_cspmu_impl_unregister(u32 pmiidr_impl);
+
#endif /* __ARM_CSPMU_H__ */
diff --git a/drivers/perf/arm_cspmu/nvidia_cspmu.c b/drivers/perf/arm_cspmu/nvidia_cspmu.c
index 72ef80caa3c8..d7083fed135d 100644
--- a/drivers/perf/arm_cspmu/nvidia_cspmu.c
+++ b/drivers/perf/arm_cspmu/nvidia_cspmu.c
@@ -1,6 +1,6 @@
// SPDX-License-Identifier: GPL-2.0
/*
- * Copyright (c) 2022, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+ * Copyright (c) 2022-2023, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
*
*/
@@ -8,7 +8,10 @@
#include <linux/topology.h>
-#include "nvidia_cspmu.h"
+#include "arm_cspmu.h"
+
+/* JEDEC-assigned JEP106 identification code */
+#define ARM_CSPMU_IMPL_ID_NVIDIA 0x36B
#define NV_PCIE_PORT_COUNT 10ULL
#define NV_PCIE_FILTER_ID_MASK GENMASK_ULL(NV_PCIE_PORT_COUNT - 1, 0)
@@ -351,7 +354,7 @@ static char *nv_cspmu_format_name(const struct arm_cspmu *cspmu,
return name;
}
-int nv_cspmu_init_ops(struct arm_cspmu *cspmu)
+static int nv_cspmu_init_ops(struct arm_cspmu *cspmu)
{
u32 prodid;
struct nv_cspmu_ctx *ctx;
@@ -395,6 +398,19 @@ int nv_cspmu_init_ops(struct arm_cspmu *cspmu)
return 0;
}
-EXPORT_SYMBOL_GPL(nv_cspmu_init_ops);
+
+static int __init nvidia_cspmu_init(void)
+{
+ return arm_cspmu_impl_register(ARM_CSPMU_IMPL_ID_NVIDIA,
+ nv_cspmu_init_ops);
+}
+
+static void __exit nvidia_cspmu_exit(void)
+{
+ arm_cspmu_impl_unregister(ARM_CSPMU_IMPL_ID_NVIDIA);
+}
+
+module_init(nvidia_cspmu_init);
+module_exit(nvidia_cspmu_exit);
MODULE_LICENSE("GPL v2");
diff --git a/drivers/perf/arm_cspmu/nvidia_cspmu.h b/drivers/perf/arm_cspmu/nvidia_cspmu.h
deleted file mode 100644
index 71e18f0dc50b..000000000000
--- a/drivers/perf/arm_cspmu/nvidia_cspmu.h
+++ /dev/null
@@ -1,17 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0
- *
- * Copyright (c) 2022, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
- *
- */
-
-/* Support for NVIDIA specific attributes. */
-
-#ifndef __NVIDIA_CSPMU_H__
-#define __NVIDIA_CSPMU_H__
-
-#include "arm_cspmu.h"
-
-/* Allocate NVIDIA descriptor. */
-int nv_cspmu_init_ops(struct arm_cspmu *cspmu);
-
-#endif /* __NVIDIA_CSPMU_H__ */

base-commit: 73f2c2a7e1d2b31fdd5faa6dfa151c437a6c0a5a
prerequisite-patch-id: fb691dc01d87597bcbaa4d352073304287c20f73

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In reply to: Besar Wicaksono: "[PATCH] perf: arm_cspmu: Separate Arm and vendor module"
Next in thread: Besar Wicaksono: "RE: [PATCH] perf: arm_cspmu: Separate Arm and vendor module"
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