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SubjectRe: [PATCH 2/2] perf: add arm64 smmuv3 pmu driver
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On 04/08/17 20:59, Neil Leeder wrote:
> Adds a new driver to support the SMMU v3 PMU and add it into the
> perf events framework.
>
> Each SMMU node may have multiple PMUs associated with it, each of
> which may support different events.
>
> PMUs are named smmu_0_<phys_addr_page> where <phys_addr_page>
> is the physical page address of the SMMU PMCG.
> For example, the SMMU PMCG at 0xff88840000 is named smmu_0_ff88840

This seems a bit rough - is it at feasible to at least chase the node
reference and namespace them by the associated component, e.g. something
like "arm-smmu-v3.x:pmcg.y"? The user can always dig the associated
physical address out of /proc/iomem if necessary.

> Filtering by stream id is done by specifying filtering parameters
> with the event. Options are:
> filter_enable - 0 = no filtering, 1 = filtering enabled
> filter_span - 0 = exact match, 1 = pattern match
> filter_sec - applies to non-secure (0) or secure (1) namespace

I'm a little dubious as to how useful it is to expose this, since we
can't see the true value of SCR.SO so have no way of knowing what we'll
actually end up counting.

> filter_stream_id - pattern to filter against
> Further filtering information is available in the SMMU documentation.
>
> Example: perf stat -e smmu_0_ff88840/transaction,filter_enable=1,
> filter_span=1,filter_stream_id=0x42/ -a pwd
> Applies filter pattern 0x42 to transaction events.
>
> SMMU events are not attributable to a CPU, so task mode and sampling
> are not supported.
>
> Signed-off-by: Neil Leeder <nleeder@codeaurora.org>
> ---
> drivers/perf/Kconfig | 9 +
> drivers/perf/Makefile | 1 +
> drivers/perf/arm_smmuv3_pmu.c | 813 ++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 823 insertions(+)
> create mode 100644 drivers/perf/arm_smmuv3_pmu.c
>
> diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig
> index e5197ff..e7721d1 100644
> --- a/drivers/perf/Kconfig
> +++ b/drivers/perf/Kconfig
> @@ -17,6 +17,15 @@ config ARM_PMU_ACPI
> depends on ARM_PMU && ACPI
> def_bool y
>
> +config ARM_SMMUV3_PMU
> + bool "ARM SMMUv3 PMU"
> + depends on PERF_EVENTS && ARM64 && ACPI

PERF_EVENTS is already a top-level dependency now.

> + help
> + Provides support for the SMMU version 3 performance monitor unit (PMU)
> + on ARM-based systems.
> + Adds the SMMU PMU into the perf events subsystem for
> + monitoring SMMU performance events.
> +
> config QCOM_L2_PMU
> bool "Qualcomm Technologies L2-cache PMU"
> depends on ARCH_QCOM && ARM64 && ACPI
> diff --git a/drivers/perf/Makefile b/drivers/perf/Makefile
> index 6420bd4..3012f5e 100644
> --- a/drivers/perf/Makefile
> +++ b/drivers/perf/Makefile
> @@ -1,5 +1,6 @@
> obj-$(CONFIG_ARM_PMU) += arm_pmu.o arm_pmu_platform.o
> obj-$(CONFIG_ARM_PMU_ACPI) += arm_pmu_acpi.o
> +obj-$(CONFIG_ARM_SMMUV3_PMU) += arm_smmuv3_pmu.o
> obj-$(CONFIG_QCOM_L2_PMU) += qcom_l2_pmu.o
> obj-$(CONFIG_QCOM_L3_PMU) += qcom_l3_pmu.o
> obj-$(CONFIG_XGENE_PMU) += xgene_pmu.o
> diff --git a/drivers/perf/arm_smmuv3_pmu.c b/drivers/perf/arm_smmuv3_pmu.c
> new file mode 100644
> index 0000000..1e70791
> --- /dev/null
> +++ b/drivers/perf/arm_smmuv3_pmu.c
> @@ -0,0 +1,813 @@
> +/* Copyright (c) 2017 The Linux Foundation. All rights reserved.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 and
> + * only version 2 as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + */
> +
> +/*
> + * This driver adds support for perf events to use the Performance
> + * Monitor Counter Groups (PMCG) associated with an SMMUv3 node
> + * to monitor that node.
> + *
> + * Devices are named smmu_0_<phys_addr_page> where <phys_addr_page>
> + * is the physical page address of the SMMU PMCG.
> + * For example, the SMMU PMCG at 0xff88840000 is named smmu_0_ff88840
> + *
> + * Filtering by stream id is done by specifying filtering parameters
> + * with the event. options are:
> + * filter_enable - 0 = no filtering, 1 = filtering enabled
> + * filter_span - 0 = exact match, 1 = pattern match
> + * filter_sec - filter applies to non-secure (0) or secure (1) namespace
> + * filter_stream_id - pattern to filter against
> + * Further filtering information is available in the SMMU documentation.
> + *
> + * Example: perf stat -e smmu_0_ff88840/transaction,filter_enable=1,
> + * filter_span=1,filter_stream_id=0x42/ -a pwd
> + * Applies filter pattern 0x42 to transaction events.
> + *
> + * SMMU events are not attributable to a CPU, so task mode and sampling
> + * are not supported.
> + */
> +
> +#include <linux/acpi.h>
> +#include <linux/acpi_iort.h>
> +#include <linux/bitops.h>
> +#include <linux/cpuhotplug.h>
> +#include <linux/cpumask.h>
> +#include <linux/device.h>
> +#include <linux/errno.h>
> +#include <linux/interrupt.h>
> +#include <linux/irq.h>
> +#include <linux/kernel.h>
> +#include <linux/list.h>
> +#include <linux/msi.h>

Is MSI support planned?

> +#include <linux/perf_event.h>
> +#include <linux/platform_device.h>
> +#include <linux/smp.h>
> +#include <linux/sysfs.h>
> +#include <linux/types.h>
> +
> +#include <asm/local64.h>
> +
> +#define SMMU_PMCG_EVCNTR0 0x0
> +#define SMMU_PMCG_EVCNTR(n, stride) (SMMU_PMCG_EVCNTR0 + (n) * (stride))
> +#define SMMU_PMCG_EVTYPER0 0x400
> +#define SMMU_PMCG_EVTYPER(n) (SMMU_PMCG_EVTYPER0 + (n) * 4)
> +#define SMMU_PMCG_EVTYPER_SEC_SID_SHIFT 30
> +#define SMMU_PMCG_EVTYPER_SID_SPAN_SHIFT 29
> +#define SMMU_PMCG_EVTYPER_EVENT_MASK GENMASK(15, 0)
> +#define SMMU_PMCG_SVR0 0x600
> +#define SMMU_PMCG_SVR(n, stride) (SMMU_PMCG_SVR0 + (n) * (stride))
> +#define SMMU_PMCG_SMR0 0xA00
> +#define SMMU_PMCG_SMR(n) (SMMU_PMCG_SMR0 + (n) * 4)
> +#define SMMU_PMCG_CNTENSET0 0xC00
> +#define SMMU_PMCG_CNTENCLR0 0xC20
> +#define SMMU_PMCG_INTENSET0 0xC40
> +#define SMMU_PMCG_INTENCLR0 0xC60
> +#define SMMU_PMCG_OVSCLR0 0xC80
> +#define SMMU_PMCG_OVSSET0 0xCC0
> +#define SMMU_PMCG_CAPR 0xD88
> +#define SMMU_PMCG_SCR 0xDF8
> +#define SMMU_PMCG_CFGR 0xE00
> +#define SMMU_PMCG_CFGR_SID_FILTER_TYPE BIT(23)
> +#define SMMU_PMCG_CFGR_CAPTURE BIT(22)
> +#define SMMU_PMCG_CFGR_MSI BIT(21)
> +#define SMMU_PMCG_CFGR_RELOC_CTRS BIT(20)
> +#define SMMU_PMCG_CFGR_SIZE_MASK GENMASK(13, 8)
> +#define SMMU_PMCG_CFGR_SIZE_SHIFT 8
> +#define SMMU_PMCG_CFGR_COUNTER_SIZE_32 31
> +#define SMMU_PMCG_CFGR_NCTR_MASK GENMASK(5, 0)
> +#define SMMU_PMCG_CFGR_NCTR_SHIFT 0
> +#define SMMU_PMCG_CR 0xE04
> +#define SMMU_PMCG_CR_ENABLE BIT(0)
> +#define SMMU_PMCG_CEID0 0xE20
> +#define SMMU_PMCG_CEID1 0xE28
> +#define SMMU_PMCG_IRQ_CTRL 0xE50
> +#define SMMU_PMCG_IRQ_CTRL_IRQEN BIT(0)
> +#define SMMU_PMCG_IRQ_CTRLACK 0xE54
> +#define SMMU_PMCG_IRQ_CTRLACK_IRQEN BIT(0)
> +#define SMMU_PMCG_IRQ_CFG0 0xE58
> +#define SMMU_PMCG_IRQ_CFG0_ADDR_MASK GENMASK(51, 2)
> +#define SMMU_PMCG_IRQ_CFG1 0xE60
> +#define SMMU_PMCG_IRQ_CFG2 0xE64
> +#define SMMU_PMCG_IRQ_STATUS 0xE68
> +#define SMMU_PMCG_IRQ_STATUS_IRQ_ABT BIT(0)
> +#define SMMU_PMCG_AIDR 0xE70

Several of these are unused (although at least IRQ0_CFG1 probably should
be, to zero it to a known state if we aren't supporting MSIs).

> +#define SMMU_COUNTER_RELOAD BIT(31)
> +#define SMMU_DEFAULT_FILTER_SEC 0
> +#define SMMU_DEFAULT_FILTER_SPAN 1
> +#define SMMU_DEFAULT_FILTER_STREAM_ID GENMASK(31, 0)
> +
> +#define SMMU_MAX_COUNTERS 64
> +#define SMMU_MAX_EVENT_ID 128
> +#define SMMU_NUM_EVENTS_U32 (SMMU_MAX_EVENT_ID / sizeof(u32))
> +
> +#define SMMU_PA_SHIFT 12
> +
> +/* Events */
> +#define SMMU_PMU_CYCLES 0
> +#define SMMU_PMU_TRANSACTION 1
> +#define SMMU_PMU_TLB_MISS 2
> +#define SMMU_PMU_CONFIG_CACHE_MISS 3
> +#define SMMU_PMU_TRANS_TABLE_WALK 4
> +#define SMMU_PMU_CONFIG_STRUCT_ACCESS 5
> +#define SMMU_PMU_PCIE_ATS_TRANS_RQ 6
> +#define SMMU_PMU_PCIE_ATS_TRANS_PASSED 7
> +
> +static int cpuhp_state_num;
> +
> +struct smmu_pmu {
> + struct hlist_node node;
> + struct perf_event *events[SMMU_MAX_COUNTERS];
> + DECLARE_BITMAP(used_counters, SMMU_MAX_COUNTERS);
> + DECLARE_BITMAP(supported_events, SMMU_MAX_EVENT_ID);
> + unsigned int irq;
> + unsigned int on_cpu;
> + struct pmu pmu;
> + unsigned int num_counters;
> + struct platform_device *pdev;
> + void __iomem *reg_base;
> + void __iomem *reloc_base;
> + u64 counter_present_mask;
> + u64 counter_mask;
> + bool reg_size_32;

This guy is redundant...

> +};
> +
> +#define to_smmu_pmu(p) (container_of(p, struct smmu_pmu, pmu))
> +
> +#define SMMU_PMU_EVENT_ATTR_EXTRACTOR(_name, _config, _size, _shift) \
> + static inline u32 get_##_name(struct perf_event *event) \
> + { \
> + return (event->attr._config >> (_shift)) & \
> + GENMASK_ULL((_size) - 1, 0); \
> + }
> +
> +SMMU_PMU_EVENT_ATTR_EXTRACTOR(event, config, 16, 0);
> +SMMU_PMU_EVENT_ATTR_EXTRACTOR(filter_stream_id, config1, 32, 0);
> +SMMU_PMU_EVENT_ATTR_EXTRACTOR(filter_span, config1, 1, 32);
> +SMMU_PMU_EVENT_ATTR_EXTRACTOR(filter_sec, config1, 1, 33);
> +SMMU_PMU_EVENT_ATTR_EXTRACTOR(filter_enable, config1, 1, 34);
> +
> +static inline void smmu_pmu_enable(struct pmu *pmu)
> +{
> + struct smmu_pmu *smmu_pmu = to_smmu_pmu(pmu);
> +
> + writel(SMMU_PMCG_CR_ENABLE, smmu_pmu->reg_base + SMMU_PMCG_CR);
> + writel(SMMU_PMCG_IRQ_CTRL_IRQEN,
> + smmu_pmu->reg_base + SMMU_PMCG_IRQ_CTRL);
> +}
> +
> +static inline void smmu_pmu_disable(struct pmu *pmu)
> +{
> + struct smmu_pmu *smmu_pmu = to_smmu_pmu(pmu);
> +
> + writel(0, smmu_pmu->reg_base + SMMU_PMCG_CR);
> + writel(0, smmu_pmu->reg_base + SMMU_PMCG_IRQ_CTRL);
> +}
> +
> +static inline void smmu_pmu_counter_set_value(struct smmu_pmu *smmu_pmu,
> + u32 idx, u64 value)
> +{
> + if (smmu_pmu->reg_size_32)

...since it would be just as efficient to directly test
smmu_pmu->counter_mask & BIT(32) here and below.

> + writel(value, smmu_pmu->reloc_base + SMMU_PMCG_EVCNTR(idx, 4));
> + else
> + writeq(value, smmu_pmu->reloc_base + SMMU_PMCG_EVCNTR(idx, 8));
> +}
> +
> +static inline u64 smmu_pmu_counter_get_value(struct smmu_pmu *smmu_pmu, u32 idx)
> +{
> + u64 value;
> +
> + if (smmu_pmu->reg_size_32)
> + value = readl(smmu_pmu->reloc_base + SMMU_PMCG_EVCNTR(idx, 4));
> + else
> + value = readq(smmu_pmu->reloc_base + SMMU_PMCG_EVCNTR(idx, 8));
> +
> + return value;
> +}
> +
> +static inline void smmu_pmu_counter_enable(struct smmu_pmu *smmu_pmu, u32 idx)
> +{
> + writeq(BIT(idx), smmu_pmu->reg_base + SMMU_PMCG_CNTENSET0);
> +}
> +
> +static inline void smmu_pmu_counter_disable(struct smmu_pmu *smmu_pmu, u32 idx)
> +{
> + writeq(BIT(idx), smmu_pmu->reg_base + SMMU_PMCG_CNTENCLR0);
> +}
> +
> +static inline void smmu_pmu_interrupt_enable(struct smmu_pmu *smmu_pmu, u32 idx)
> +{
> + writeq(BIT(idx), smmu_pmu->reg_base + SMMU_PMCG_INTENSET0);
> +}
> +
> +static inline void smmu_pmu_interrupt_disable(struct smmu_pmu *smmu_pmu,
> + u32 idx)
> +{
> + writeq(BIT(idx), smmu_pmu->reg_base + SMMU_PMCG_INTENCLR0);
> +}
> +
> +static void smmu_pmu_reset(struct smmu_pmu *smmu_pmu)
> +{
> + unsigned int i;
> +
> + for (i = 0; i < smmu_pmu->num_counters; i++) {
> + smmu_pmu_counter_disable(smmu_pmu, i);
> + smmu_pmu_interrupt_disable(smmu_pmu, i);
> + }

Surely it would be far quicker and simpler to do this?

writeq(smmu_pmu->counter_present_mask,
smmu_pmu->reg_base + SMMU_PMCG_CNTENCLR0);
writeq(smmu_pmu->counter_present_mask,
smmu_pmu->reg_base + SMMU_PMCG_INTENCLR0);

> + smmu_pmu_disable(&smmu_pmu->pmu);
> +}
> +
> +static inline void smmu_pmu_set_evtyper(struct smmu_pmu *smmu_pmu, u32 idx,
> + u32 val)
> +{
> + writel(val, smmu_pmu->reg_base + SMMU_PMCG_EVTYPER(idx));
> +}
> +
> +static inline void smmu_pmu_set_smr(struct smmu_pmu *smmu_pmu, u32 idx, u32 val)
> +{
> + writel(val, smmu_pmu->reg_base + SMMU_PMCG_SMR(idx));
> +}
> +
> +static inline u64 smmu_pmu_getreset_ovsr(struct smmu_pmu *smmu_pmu)
> +{
> + u64 result = readq_relaxed(smmu_pmu->reloc_base + SMMU_PMCG_OVSSET0);
> +
> + writeq(result, smmu_pmu->reloc_base + SMMU_PMCG_OVSCLR0);
> + return result;
> +}
> +
> +static inline bool smmu_pmu_has_overflowed(struct smmu_pmu *smmu_pmu, u64 ovsr)
> +{
> + return !!(ovsr & smmu_pmu->counter_present_mask);
> +}

Personally, I find these helpers abstracting simple reads/writes
actually make the code harder to follow, especially when they're each
used a grand total of once. That may well just be me, though.

> +static void smmu_pmu_event_update(struct perf_event *event)
> +{
> + struct hw_perf_event *hwc = &event->hw;
> + struct smmu_pmu *smmu_pmu = to_smmu_pmu(event->pmu);
> + u64 delta, prev, now;
> + u32 idx = hwc->idx;
> +
> + do {
> + prev = local64_read(&hwc->prev_count);
> + now = smmu_pmu_counter_get_value(smmu_pmu, idx);
> + } while (local64_cmpxchg(&hwc->prev_count, prev, now) != prev);
> +
> + /* handle overflow. */
> + delta = now - prev;
> + delta &= smmu_pmu->counter_mask;
> +
> + local64_add(delta, &event->count);
> +}
> +
> +static void smmu_pmu_set_period(struct smmu_pmu *smmu_pmu,
> + struct hw_perf_event *hwc)
> +{
> + u32 idx = hwc->idx;
> + u64 new;
> +
> + /*
> + * We limit the max period to half the max counter value of the smallest
> + * counter size, so that even in the case of extreme interrupt latency
> + * the counter will (hopefully) not wrap past its initial value.
> + */

Having once fought to properly understand the underlying logic I despise
this unhelpfully-vague comment, but that's not your fault ;)

> + new = SMMU_COUNTER_RELOAD;

Given that we *are* following the "use the top counter bit as an
implicit overflow bit" pattern of arm_pmu, it feels a bit weird to not
use the actual half-maximum value here (especially since it's easily
computable from counter_mask). I'm about 85% sure it probably still
works, but as ever inconsistency breeds uncertainty.
> + local64_set(&hwc->prev_count, new);
> + smmu_pmu_counter_set_value(smmu_pmu, idx, new);
> +}
> +
> +static irqreturn_t smmu_pmu_handle_irq(int irq_num, void *data)
> +{
> + struct smmu_pmu *smmu_pmu = data;
> + u64 ovsr;
> + unsigned int idx;
> +
> + ovsr = smmu_pmu_getreset_ovsr(smmu_pmu);
> + if (!smmu_pmu_has_overflowed(smmu_pmu, ovsr))

You have an architectural guarantee that unimplemented bits of OVSSET0
are RES0, so checking !ovsr is sufficient.

> + return IRQ_NONE;
> +
> + for_each_set_bit(idx, (unsigned long *)&ovsr, smmu_pmu->num_counters) {
> + struct perf_event *event = smmu_pmu->events[idx];
> + struct hw_perf_event *hwc;
> +
> + if (WARN_ON_ONCE(!event))
> + continue;
> +
> + smmu_pmu_event_update(event);
> + hwc = &event->hw;
> +
> + smmu_pmu_set_period(smmu_pmu, hwc);
> + }
> +
> + return IRQ_HANDLED;
> +}
> +
> +static unsigned int smmu_pmu_get_event_idx(struct smmu_pmu *smmu_pmu)
> +{
> + unsigned int idx;
> + unsigned int num_ctrs = smmu_pmu->num_counters;
> +
> + idx = find_first_zero_bit(smmu_pmu->used_counters, num_ctrs);
> + if (idx == num_ctrs)
> + /* The counters are all in use. */
> + return -EAGAIN;
> +
> + set_bit(idx, smmu_pmu->used_counters);
> +
> + return idx;
> +}
> +
> +/*
> + * Implementation of abstract pmu functionality required by
> + * the core perf events code.
> + */
> +
> +static int smmu_pmu_event_init(struct perf_event *event)
> +{
> + struct hw_perf_event *hwc = &event->hw;
> + struct perf_event *sibling;
> + struct smmu_pmu *smmu_pmu;
> + u32 event_id;
> +
> + if (event->attr.type != event->pmu->type)
> + return -ENOENT;
> +
> + smmu_pmu = to_smmu_pmu(event->pmu);
> +
> + if (hwc->sample_period) {
> + dev_dbg_ratelimited(&smmu_pmu->pdev->dev,
> + "Sampling not supported\n");
> + return -EOPNOTSUPP;
> + }
> +
> + if (event->cpu < 0) {
> + dev_dbg_ratelimited(&smmu_pmu->pdev->dev,
> + "Per-task mode not supported\n");
> + return -EOPNOTSUPP;
> + }
> +
> + /* We cannot filter accurately so we just don't allow it. */
> + if (event->attr.exclude_user || event->attr.exclude_kernel ||
> + event->attr.exclude_hv || event->attr.exclude_idle) {
> + dev_dbg_ratelimited(&smmu_pmu->pdev->dev,
> + "Can't exclude execution levels\n");
> + return -EOPNOTSUPP;
> + }
> +
> + /* Verify specified event is supported on this PMU */
> + event_id = get_event(event);
> + if ((event_id >= SMMU_MAX_EVENT_ID) ||

What about raw imp-def events?

> + (!test_bit(event_id, smmu_pmu->supported_events))) {
> + dev_dbg_ratelimited(&smmu_pmu->pdev->dev,
> + "Invalid event %d for this PMU\n",
> + event_id);
> + return -EINVAL;
> + }
> +
> + /* Don't allow groups with mixed PMUs, except for s/w events */
> + if (event->group_leader->pmu != event->pmu &&
> + !is_software_event(event->group_leader)) {
> + dev_dbg_ratelimited(&smmu_pmu->pdev->dev,
> + "Can't create mixed PMU group\n");
> + return -EINVAL;
> + }
> +
> + list_for_each_entry(sibling, &event->group_leader->sibling_list,
> + group_entry)
> + if (sibling->pmu != event->pmu &&
> + !is_software_event(sibling)) {
> + dev_dbg_ratelimited(&smmu_pmu->pdev->dev,
> + "Can't create mixed PMU group\n");
> + return -EINVAL;
> + }
> +
> + /* Ensure all events in a group are on the same cpu */
> + if ((event->group_leader != event) &&
> + (event->cpu != event->group_leader->cpu)) {
> + dev_dbg_ratelimited(&smmu_pmu->pdev->dev,
> + "Can't create group on CPUs %d and %d",
> + event->cpu, event->group_leader->cpu);
> + return -EINVAL;
> + }
> +
> + hwc->idx = -1;
> +
> + /*
> + * Ensure all events are on the same cpu so all events are in the
> + * same cpu context, to avoid races on pmu_enable etc.
> + */
> + event->cpu = smmu_pmu->on_cpu;
> +
> + return 0;
> +}
> +
> +static void smmu_pmu_event_start(struct perf_event *event, int flags)
> +{
> + struct smmu_pmu *smmu_pmu = to_smmu_pmu(event->pmu);
> + struct hw_perf_event *hwc = &event->hw;
> + int idx = hwc->idx;
> + u32 evtyper;
> + u32 filter_sec;
> + u32 filter_span;
> + u32 filter_stream_id;
> +
> + hwc->state = 0;
> +
> + smmu_pmu_set_period(smmu_pmu, hwc);
> +
> + if (get_filter_enable(event)) {
> + filter_sec = get_filter_sec(event);
> + filter_span = get_filter_span(event);
> + filter_stream_id = get_filter_stream_id(event);
> + } else {
> + filter_sec = SMMU_DEFAULT_FILTER_SEC;
> + filter_span = SMMU_DEFAULT_FILTER_SPAN;
> + filter_stream_id = SMMU_DEFAULT_FILTER_STREAM_ID;
> + }
> +
> + evtyper = get_event(event) |
> + filter_span << SMMU_PMCG_EVTYPER_SID_SPAN_SHIFT |
> + filter_sec << SMMU_PMCG_EVTYPER_SEC_SID_SHIFT;
> +
> + smmu_pmu_set_evtyper(smmu_pmu, idx, evtyper);
> + smmu_pmu_set_smr(smmu_pmu, idx, filter_stream_id);
> + smmu_pmu_interrupt_enable(smmu_pmu, idx);
> + smmu_pmu_counter_enable(smmu_pmu, idx);
> +}
> +
> +static void smmu_pmu_event_stop(struct perf_event *event, int flags)
> +{
> + struct smmu_pmu *smmu_pmu = to_smmu_pmu(event->pmu);
> + struct hw_perf_event *hwc = &event->hw;
> + int idx = hwc->idx;
> +
> + if (hwc->state & PERF_HES_STOPPED)
> + return;
> +
> + smmu_pmu_interrupt_disable(smmu_pmu, idx);
> + smmu_pmu_counter_disable(smmu_pmu, idx);
> +
> + if (flags & PERF_EF_UPDATE)
> + smmu_pmu_event_update(event);
> + hwc->state |= PERF_HES_STOPPED | PERF_HES_UPTODATE;
> +}
> +
> +static int smmu_pmu_event_add(struct perf_event *event, int flags)
> +{
> + struct hw_perf_event *hwc = &event->hw;
> + int idx;
> + struct smmu_pmu *smmu_pmu = to_smmu_pmu(event->pmu);
> +
> + idx = smmu_pmu_get_event_idx(smmu_pmu);
> + if (idx < 0)
> + return idx;
> +
> + hwc->idx = idx;
> + hwc->state = PERF_HES_STOPPED | PERF_HES_UPTODATE;
> + smmu_pmu->events[idx] = event;
> + local64_set(&hwc->prev_count, 0);
> +
> + if (flags & PERF_EF_START)
> + smmu_pmu_event_start(event, flags);
> +
> + /* Propagate changes to the userspace mapping. */
> + perf_event_update_userpage(event);
> +
> + return 0;
> +}
> +
> +static void smmu_pmu_event_del(struct perf_event *event, int flags)
> +{
> + struct hw_perf_event *hwc = &event->hw;
> + struct smmu_pmu *smmu_pmu = to_smmu_pmu(event->pmu);
> + int idx = hwc->idx;
> +
> + smmu_pmu_event_stop(event, flags | PERF_EF_UPDATE);
> + smmu_pmu->events[idx] = NULL;
> + clear_bit(idx, smmu_pmu->used_counters);
> +
> + perf_event_update_userpage(event);
> +}
> +
> +static void smmu_pmu_event_read(struct perf_event *event)
> +{
> + smmu_pmu_event_update(event);
> +}
> +
> +/* cpumask */
> +
> +static ssize_t smmu_pmu_cpumask_show(struct device *dev,
> + struct device_attribute *attr,
> + char *buf)
> +{
> + struct smmu_pmu *smmu_pmu = to_smmu_pmu(dev_get_drvdata(dev));
> +
> + return cpumap_print_to_pagebuf(true, buf, cpumask_of(smmu_pmu->on_cpu));
> +}
> +
> +static struct device_attribute smmu_pmu_cpumask_attr =
> + __ATTR(cpumask, 0444, smmu_pmu_cpumask_show, NULL);
> +
> +static struct attribute *smmu_pmu_cpumask_attrs[] = {
> + &smmu_pmu_cpumask_attr.attr,
> + NULL,
> +};
> +
> +static struct attribute_group smmu_pmu_cpumask_group = {
> + .attrs = smmu_pmu_cpumask_attrs,
> +};
> +
> +/* Events */
> +
> +ssize_t smmu_pmu_event_show(struct device *dev,
> + struct device_attribute *attr, char *page)
> +{
> + struct perf_pmu_events_attr *pmu_attr;
> +
> + pmu_attr = container_of(attr, struct perf_pmu_events_attr, attr);
> +
> + return sprintf(page, "event=0x%02llx\n", pmu_attr->id);
> +}
> +
> +#define SMMU_EVENT_ATTR(_name, _id) \
> + (&((struct perf_pmu_events_attr[]) { \
> + { .attr = __ATTR(_name, 0444, smmu_pmu_event_show, NULL), \
> + .id = _id, } \
> + })[0].attr.attr)
> +
> +static struct attribute *smmu_pmu_events[] = {
> + SMMU_EVENT_ATTR(cycles, SMMU_PMU_CYCLES),
> + SMMU_EVENT_ATTR(transaction, SMMU_PMU_TRANSACTION),
> + SMMU_EVENT_ATTR(tlb_miss, SMMU_PMU_TLB_MISS),
> + SMMU_EVENT_ATTR(config_cache_miss, SMMU_PMU_CONFIG_CACHE_MISS),
> + SMMU_EVENT_ATTR(trans_table_walk, SMMU_PMU_TRANS_TABLE_WALK),
> + SMMU_EVENT_ATTR(config_struct_access, SMMU_PMU_CONFIG_STRUCT_ACCESS),
> + SMMU_EVENT_ATTR(pcie_ats_trans_rq, SMMU_PMU_PCIE_ATS_TRANS_RQ),
> + SMMU_EVENT_ATTR(pcie_ats_trans_passed, SMMU_PMU_PCIE_ATS_TRANS_PASSED),
> + NULL
> +};
> +
> +static umode_t smmu_pmu_event_is_visible(struct kobject *kobj,
> + struct attribute *attr, int unused)
> +{
> + struct device *dev = kobj_to_dev(kobj);
> + struct smmu_pmu *smmu_pmu = to_smmu_pmu(dev_get_drvdata(dev));
> + struct perf_pmu_events_attr *pmu_attr;
> +
> + pmu_attr = container_of(attr, struct perf_pmu_events_attr, attr.attr);
> +
> + if (test_bit(pmu_attr->id, smmu_pmu->supported_events))
> + return attr->mode;
> +
> + return 0;
> +}
> +static struct attribute_group smmu_pmu_events_group = {
> + .name = "events",
> + .attrs = smmu_pmu_events,
> + .is_visible = smmu_pmu_event_is_visible,
> +};
> +
> +/* Formats */
> +PMU_FORMAT_ATTR(event, "config:0-15");
> +PMU_FORMAT_ATTR(filter_stream_id, "config1:0-31");
> +PMU_FORMAT_ATTR(filter_span, "config1:32");
> +PMU_FORMAT_ATTR(filter_sec, "config1:33");
> +PMU_FORMAT_ATTR(filter_enable, "config1:34");
> +
> +static struct attribute *smmu_pmu_formats[] = {
> + &format_attr_event.attr,
> + &format_attr_filter_stream_id.attr,
> + &format_attr_filter_span.attr,
> + &format_attr_filter_sec.attr,
> + &format_attr_filter_enable.attr,
> + NULL
> +};
> +
> +static struct attribute_group smmu_pmu_format_group = {
> + .name = "format",
> + .attrs = smmu_pmu_formats,
> +};
> +
> +static const struct attribute_group *smmu_pmu_attr_grps[] = {
> + &smmu_pmu_cpumask_group,
> + &smmu_pmu_events_group,
> + &smmu_pmu_format_group,
> + NULL,
> +};
> +
> +/*
> + * Generic device handlers
> + */
> +
> +static unsigned int get_num_counters(struct smmu_pmu *smmu_pmu)
> +{
> + u32 cfgr = readl(smmu_pmu->reg_base + SMMU_PMCG_CFGR);
> +
> + return ((cfgr & SMMU_PMCG_CFGR_NCTR_MASK) >> SMMU_PMCG_CFGR_NCTR_SHIFT)
> + + 1;
> +}
> +
> +static int smmu_pmu_offline_cpu(unsigned int cpu, struct hlist_node *node)
> +{
> + struct smmu_pmu *smmu_pmu;
> + unsigned int target;
> +
> + smmu_pmu = hlist_entry_safe(node, struct smmu_pmu, node);

Is it ever valid for node to be NULL? If we can't trust it to be one of
the PMUs we registered I think all bets are off anyway.

> + if (cpu != smmu_pmu->on_cpu)
> + return 0;
> +
> + target = cpumask_any_but(cpu_online_mask, cpu);
> + if (target >= nr_cpu_ids)
> + return 0;
> +
> + perf_pmu_migrate_context(&smmu_pmu->pmu, cpu, target);
> + smmu_pmu->on_cpu = target;
> + WARN_ON(irq_set_affinity(smmu_pmu->irq, cpumask_of(target)));
> +
> + return 0;
> +}
> +
> +static int smmu_pmu_probe(struct platform_device *pdev)
> +{
> + struct smmu_pmu *smmu_pmu;
> + struct resource *mem_resource_0, *mem_resource_1;
> + void __iomem *mem_map_0, *mem_map_1;
> + unsigned int reg_size;
> + int err;
> + int irq;
> + u32 ceid[SMMU_NUM_EVENTS_U32];
> + u64 ceid_64;
> +
> + smmu_pmu = devm_kzalloc(&pdev->dev, sizeof(*smmu_pmu), GFP_KERNEL);
> + if (!smmu_pmu)
> + return -ENOMEM;
> +
> + platform_set_drvdata(pdev, smmu_pmu);
> + smmu_pmu->pmu = (struct pmu) {
> + .task_ctx_nr = perf_invalid_context,
> + .pmu_enable = smmu_pmu_enable,
> + .pmu_disable = smmu_pmu_disable,
> + .event_init = smmu_pmu_event_init,
> + .add = smmu_pmu_event_add,
> + .del = smmu_pmu_event_del,
> + .start = smmu_pmu_event_start,
> + .stop = smmu_pmu_event_stop,
> + .read = smmu_pmu_event_read,
> + .attr_groups = smmu_pmu_attr_grps,
> + };
> +
> + mem_resource_0 = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + mem_map_0 = devm_ioremap_resource(&pdev->dev, mem_resource_0);
> +
> + if (IS_ERR(mem_map_0)) {
> + dev_err(&pdev->dev, "Can't map SMMU PMU @%pa\n",
> + &mem_resource_0->start);
> + return PTR_ERR(mem_map_0);
> + }
> +
> + smmu_pmu->reg_base = mem_map_0;
> + smmu_pmu->pmu.name =
> + devm_kasprintf(&pdev->dev, GFP_KERNEL, "smmu_0_%llx",
> + (mem_resource_0->start) >> SMMU_PA_SHIFT);
> +
> + if (!smmu_pmu->pmu.name) {
> + dev_err(&pdev->dev, "Failed to create PMU name");
> + return -EINVAL;
> + }
> +
> + ceid_64 = readq(smmu_pmu->reg_base + SMMU_PMCG_CEID0);
> + ceid[0] = ceid_64 & GENMASK(31, 0);

It took a second look to determine that that masking does nothing...

> + ceid[1] = ceid_64 >> 32;
> + ceid_64 = readq(smmu_pmu->reg_base + SMMU_PMCG_CEID1);
> + ceid[2] = ceid_64 & GENMASK(31, 0);
> + ceid[3] = ceid_64 >> 32;
> + bitmap_from_u32array(smmu_pmu->supported_events, SMMU_MAX_EVENT_ID,
> + ceid, SMMU_NUM_EVENTS_U32);

...but then the whole lot might be cleaner and simpler with a u64[2]
cast to u32* (or unioned to u32[4]) as necessary.

> +
> + /* Determine if page 1 is present */
> + if (readl(smmu_pmu->reg_base + SMMU_PMCG_CFGR) &
> + SMMU_PMCG_CFGR_RELOC_CTRS) {
> + mem_resource_1 = platform_get_resource(pdev, IORESOURCE_MEM, 1);
> + mem_map_1 = devm_ioremap_resource(&pdev->dev, mem_resource_1);
> +
> + if (IS_ERR(mem_map_1)) {
> + dev_err(&pdev->dev, "Can't map SMMU PMU @%pa\n",
> + &mem_resource_1->start);
> + return PTR_ERR(mem_map_1);
> + }
> + smmu_pmu->reloc_base = mem_map_1;
> + } else {
> + smmu_pmu->reloc_base = smmu_pmu->reg_base;
> + }
> +
> + irq = platform_get_irq(pdev, 0);
> + if (irq < 0) {
> + dev_err(&pdev->dev,
> + "Failed to get valid irq for smmu @%pa\n",
> + &mem_resource_0->start);
> + return irq;
> + }
> +
> + err = devm_request_irq(&pdev->dev, irq, smmu_pmu_handle_irq,
> + IRQF_NOBALANCING | IRQF_SHARED | IRQF_NO_THREAD,
> + "smmu-pmu", smmu_pmu);
> + if (err) {
> + dev_err(&pdev->dev,
> + "Unable to request IRQ%d for SMMU PMU counters\n", irq);
> + return err;
> + }
> +
> + smmu_pmu->irq = irq;
> +
> + /* Pick one CPU to be the preferred one to use */
> + smmu_pmu->on_cpu = smp_processor_id();
> + WARN_ON(irq_set_affinity(smmu_pmu->irq, cpumask_of(smmu_pmu->on_cpu)));
> +
> + smmu_pmu->num_counters = get_num_counters(smmu_pmu);
> + smmu_pmu->pdev = pdev;
> + smmu_pmu->counter_present_mask = GENMASK(smmu_pmu->num_counters - 1, 0);
> + reg_size = (readl(smmu_pmu->reg_base + SMMU_PMCG_CFGR) &
> + SMMU_PMCG_CFGR_SIZE_MASK) >> SMMU_PMCG_CFGR_SIZE_SHIFT;
> + smmu_pmu->reg_size_32 = (reg_size == SMMU_PMCG_CFGR_COUNTER_SIZE_32);
> + smmu_pmu->counter_mask = GENMASK_ULL(reg_size, 0);
> +
> + smmu_pmu_reset(smmu_pmu);
> +
> + err = cpuhp_state_add_instance_nocalls(cpuhp_state_num,
> + &smmu_pmu->node);
> + if (err) {
> + dev_err(&pdev->dev, "Error %d registering hotplug", err);
> + return err;
> + }
> +
> + err = perf_pmu_register(&smmu_pmu->pmu, smmu_pmu->pmu.name, -1);
> + if (err) {
> + dev_err(&pdev->dev, "Error %d registering SMMU PMU\n", err);
> + goto out_unregister;
> + }
> +
> + dev_info(&pdev->dev, "Registered SMMU PMU @ %pa using %d counters\n",
> + &mem_resource_0->start, smmu_pmu->num_counters);
> +
> + return err;
> +
> +out_unregister:
> + cpuhp_state_remove_instance_nocalls(cpuhp_state_num, &smmu_pmu->node);
> + return err;
> +}
> +
> +static int smmu_pmu_remove(struct platform_device *pdev)
> +{
> + struct smmu_pmu *smmu_pmu = platform_get_drvdata(pdev);
> +
> + perf_pmu_unregister(&smmu_pmu->pmu);
> + cpuhp_state_remove_instance_nocalls(cpuhp_state_num, &smmu_pmu->node);
> +
> + return 0;
> +}
> +
> +static void smmu_pmu_shutdown(struct platform_device *pdev)
> +{
> + struct smmu_pmu *smmu_pmu = platform_get_drvdata(pdev);
> +
> + smmu_pmu_disable(&smmu_pmu->pmu);
> +}
> +
> +static struct platform_driver smmu_pmu_driver = {
> + .driver = {
> + .name = "arm-smmu-pmu",

Nit: "arm-smmu-v3-pmu" please, for consistency with the IOMMU driver
naming. There is a SMMUv2 PMU driver in the works, too ;)

Robin.

> + },
> + .probe = smmu_pmu_probe,
> + .remove = smmu_pmu_remove,
> + .shutdown = smmu_pmu_shutdown,
> +};
> +
> +static int __init arm_smmu_pmu_init(void)
> +{
> + cpuhp_state_num = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN,
> + "perf/arm/smmupmu:online",
> + NULL,
> + smmu_pmu_offline_cpu);
> + if (cpuhp_state_num < 0)
> + return cpuhp_state_num;
> +
> + return platform_driver_register(&smmu_pmu_driver);
> +}
> +module_init(arm_smmu_pmu_init);
> +
> +static void __exit arm_smmu_pmu_exit(void)
> +{
> + platform_driver_unregister(&smmu_pmu_driver);
> +}
> +
> +module_exit(arm_smmu_pmu_exit);
> +MODULE_LICENSE("GPL v2");
>

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