Re: [PATCH v2 1/2] drivers/perf: riscv-iommu: add risc-v iommu pmu driver

From: Zong Li

Date: Mon Jun 22 2026 - 21:47:33 EST

On Sat, Jun 20, 2026 at 12:06 AM Guo Ren <guoren@xxxxxxxxxx> wrote:
>
> On Sat, Feb 07, 2026 at 10:38:35PM -0800, Zong Li wrote:
> > Add a new driver to support the RISC-V IOMMU PMU. This is an auxiliary
> > device driver created by the parent RISC-V IOMMU driver.
> >
> > The RISC-V IOMMU PMU separates the cycle counter from the event counters.
> > The cycle counter is not associated with iohpmevt0, so a software-defined
> > cycle event is required for the perf subsystem.
> >
> > The number and width of the counters are hardware-implemented and must
> > be detected at runtime.
> >
> > The performance monitor provides counters with filtering support to
> > collect events for specific device ID/process ID, or GSCID/PSCID.
> >
> > PMU-related definitions are moved into the perf driver, where they are
> > used exclusively.
> >
> > Signed-off-by: Zong Li <zong.li@xxxxxxxxxx>
> > ---
> > drivers/iommu/riscv/iommu-bits.h | 61 ---
> > drivers/perf/Kconfig | 12 +
> > drivers/perf/Makefile | 1 +
> > drivers/perf/riscv_iommu_pmu.c | 661 +++++++++++++++++++++++++++++++
> > 4 files changed, 674 insertions(+), 61 deletions(-)
> > create mode 100644 drivers/perf/riscv_iommu_pmu.c
> >
> > diff --git a/drivers/iommu/riscv/iommu-bits.h b/drivers/iommu/riscv/iommu-bits.h
> > index 98daf0e1a306..746cd11f4938 100644
> > --- a/drivers/iommu/riscv/iommu-bits.h
> > +++ b/drivers/iommu/riscv/iommu-bits.h
> > @@ -189,67 +189,6 @@ enum riscv_iommu_ddtp_modes {
> > #define RISCV_IOMMU_IPSR_PMIP BIT(RISCV_IOMMU_INTR_PM)
> > #define RISCV_IOMMU_IPSR_PIP BIT(RISCV_IOMMU_INTR_PQ)
> >
> > -/* 5.19 Performance monitoring counter overflow status (32bits) */
> > -#define RISCV_IOMMU_REG_IOCOUNTOVF 0x0058
> > -#define RISCV_IOMMU_IOCOUNTOVF_CY BIT(0)
> > -#define RISCV_IOMMU_IOCOUNTOVF_HPM GENMASK_ULL(31, 1)
> > -
> > -/* 5.20 Performance monitoring counter inhibits (32bits) */
> > -#define RISCV_IOMMU_REG_IOCOUNTINH 0x005C
> > -#define RISCV_IOMMU_IOCOUNTINH_CY BIT(0)
> > -#define RISCV_IOMMU_IOCOUNTINH_HPM GENMASK(31, 1)
> > -
> > -/* 5.21 Performance monitoring cycles counter (64bits) */
> > -#define RISCV_IOMMU_REG_IOHPMCYCLES 0x0060
> > -#define RISCV_IOMMU_IOHPMCYCLES_COUNTER GENMASK_ULL(62, 0)
> > -#define RISCV_IOMMU_IOHPMCYCLES_OF BIT_ULL(63)
> > -
> > -/* 5.22 Performance monitoring event counters (31 * 64bits) */
> > -#define RISCV_IOMMU_REG_IOHPMCTR_BASE 0x0068
> > -#define RISCV_IOMMU_REG_IOHPMCTR(_n) (RISCV_IOMMU_REG_IOHPMCTR_BASE + ((_n) * 0x8))
> > -
> > -/* 5.23 Performance monitoring event selectors (31 * 64bits) */
> > -#define RISCV_IOMMU_REG_IOHPMEVT_BASE 0x0160
> > -#define RISCV_IOMMU_REG_IOHPMEVT(_n) (RISCV_IOMMU_REG_IOHPMEVT_BASE + ((_n) * 0x8))
> > -#define RISCV_IOMMU_IOHPMEVT_EVENTID GENMASK_ULL(14, 0)
> > -#define RISCV_IOMMU_IOHPMEVT_DMASK BIT_ULL(15)
> > -#define RISCV_IOMMU_IOHPMEVT_PID_PSCID GENMASK_ULL(35, 16)
> > -#define RISCV_IOMMU_IOHPMEVT_DID_GSCID GENMASK_ULL(59, 36)
> > -#define RISCV_IOMMU_IOHPMEVT_PV_PSCV BIT_ULL(60)
> > -#define RISCV_IOMMU_IOHPMEVT_DV_GSCV BIT_ULL(61)
> > -#define RISCV_IOMMU_IOHPMEVT_IDT BIT_ULL(62)
> > -#define RISCV_IOMMU_IOHPMEVT_OF BIT_ULL(63)
> > -
> > -/* Number of defined performance-monitoring event selectors */
> > -#define RISCV_IOMMU_IOHPMEVT_CNT 31
> > -
> > -/**
> > - * enum riscv_iommu_hpmevent_id - Performance-monitoring event identifier
> > - *
> > - * @RISCV_IOMMU_HPMEVENT_INVALID: Invalid event, do not count
> > - * @RISCV_IOMMU_HPMEVENT_URQ: Untranslated requests
> > - * @RISCV_IOMMU_HPMEVENT_TRQ: Translated requests
> > - * @RISCV_IOMMU_HPMEVENT_ATS_RQ: ATS translation requests
> > - * @RISCV_IOMMU_HPMEVENT_TLB_MISS: TLB misses
> > - * @RISCV_IOMMU_HPMEVENT_DD_WALK: Device directory walks
> > - * @RISCV_IOMMU_HPMEVENT_PD_WALK: Process directory walks
> > - * @RISCV_IOMMU_HPMEVENT_S_VS_WALKS: First-stage page table walks
> > - * @RISCV_IOMMU_HPMEVENT_G_WALKS: Second-stage page table walks
> > - * @RISCV_IOMMU_HPMEVENT_MAX: Value to denote maximum Event IDs
> > - */
> > -enum riscv_iommu_hpmevent_id {
> > - RISCV_IOMMU_HPMEVENT_INVALID = 0,
> > - RISCV_IOMMU_HPMEVENT_URQ = 1,
> > - RISCV_IOMMU_HPMEVENT_TRQ = 2,
> > - RISCV_IOMMU_HPMEVENT_ATS_RQ = 3,
> > - RISCV_IOMMU_HPMEVENT_TLB_MISS = 4,
> > - RISCV_IOMMU_HPMEVENT_DD_WALK = 5,
> > - RISCV_IOMMU_HPMEVENT_PD_WALK = 6,
> > - RISCV_IOMMU_HPMEVENT_S_VS_WALKS = 7,
> > - RISCV_IOMMU_HPMEVENT_G_WALKS = 8,
> > - RISCV_IOMMU_HPMEVENT_MAX = 9
> > -};
> > -
> > /* 5.24 Translation request IOVA (64bits) */
> > #define RISCV_IOMMU_REG_TR_REQ_IOVA 0x0258
> > #define RISCV_IOMMU_TR_REQ_IOVA_VPN GENMASK_ULL(63, 12)
> > diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig
> > index 638321fc9800..6d0ece827501 100644
> > --- a/drivers/perf/Kconfig
> > +++ b/drivers/perf/Kconfig
> > @@ -105,6 +105,18 @@ config RISCV_PMU_SBI
> > full perf feature support i.e. counter overflow, privilege mode
> > filtering, counter configuration.
> >
> > +config RISCV_IOMMU_PMU
> > + depends on RISCV || COMPILE_TEST
> > + depends on RISCV_IOMMU
> > + bool "RISC-V IOMMU Hardware Performance Monitor"
> > + default y
> > + help
> > + Say Y if you want to use the RISC-V IOMMU performance monitor
> > + implementation. The performance monitor is an optional hardware
> > + feature, and whether it is actually enabled depends on IOMMU
> > + hardware support. If the underlying hardware does not implement
> > + the PMU, this option will have no effect.
> > +
> > config STARFIVE_STARLINK_PMU
> > depends on ARCH_STARFIVE || COMPILE_TEST
> > depends on 64BIT
> > diff --git a/drivers/perf/Makefile b/drivers/perf/Makefile
> > index ea52711a87e3..f64f7dc046f1 100644
> > --- a/drivers/perf/Makefile
> > +++ b/drivers/perf/Makefile
> > @@ -20,6 +20,7 @@ obj-$(CONFIG_QCOM_L3_PMU) += qcom_l3_pmu.o
> > obj-$(CONFIG_RISCV_PMU) += riscv_pmu.o
> > obj-$(CONFIG_RISCV_PMU_LEGACY) += riscv_pmu_legacy.o
> > obj-$(CONFIG_RISCV_PMU_SBI) += riscv_pmu_sbi.o
> > +obj-$(CONFIG_RISCV_IOMMU_PMU) += riscv_iommu_pmu.o
> > obj-$(CONFIG_STARFIVE_STARLINK_PMU) += starfive_starlink_pmu.o
> > obj-$(CONFIG_THUNDERX2_PMU) += thunderx2_pmu.o
> > obj-$(CONFIG_XGENE_PMU) += xgene_pmu.o
> > diff --git a/drivers/perf/riscv_iommu_pmu.c b/drivers/perf/riscv_iommu_pmu.c
> > new file mode 100644
> > index 000000000000..72fc4341b165
> > --- /dev/null
> > +++ b/drivers/perf/riscv_iommu_pmu.c
> > @@ -0,0 +1,661 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * Copyright (C) 2026 SiFive
> > + *
> > + * Authors
> > + * Zong Li <zong.li@xxxxxxxxxx>
> > + */
> > +
> > +#include <linux/auxiliary_bus.h>
> > +#include <linux/io-64-nonatomic-hi-lo.h>
> > +#include <linux/perf_event.h>
> > +
> > +#include "../iommu/riscv/iommu.h"
> > +
> > +/* 5.19 Performance monitoring counter overflow status (32bits) */
> > +#define RISCV_IOMMU_REG_IOCOUNTOVF 0x0058
> > +#define RISCV_IOMMU_IOCOUNTOVF_CY BIT(0)
> > +#define RISCV_IOMMU_IOCOUNTOVF_HPM GENMASK_ULL(31, 1)
> > +
> > +/* 5.20 Performance monitoring counter inhibits (32bits) */
> > +#define RISCV_IOMMU_REG_IOCOUNTINH 0x005C
> > +#define RISCV_IOMMU_IOCOUNTINH_CY BIT(0)
> > +#define RISCV_IOMMU_IOCOUNTINH_HPM GENMASK(31, 0)
> > +
> > +/* 5.21 Performance monitoring cycles counter (64bits) */
> > +#define RISCV_IOMMU_REG_IOHPMCYCLES 0x0060
> > +#define RISCV_IOMMU_IOHPMCYCLES_COUNTER GENMASK_ULL(62, 0)
> > +#define RISCV_IOMMU_IOHPMCYCLES_OF BIT_ULL(63)
> > +#define RISCV_IOMMU_REG_IOHPMCTR(_n) (RISCV_IOMMU_REG_IOHPMCYCLES + ((_n) * 0x8))
> > +
> > +/* 5.22 Performance monitoring event counters (31 * 64bits) */
> > +#define RISCV_IOMMU_REG_IOHPMCTR_BASE 0x0068
> > +#define RISCV_IOMMU_IOHPMCTR_COUNTER GENMASK_ULL(63, 0)
> > +
> > +/* 5.23 Performance monitoring event selectors (31 * 64bits) */
> > +#define RISCV_IOMMU_REG_IOHPMEVT_BASE 0x0160
> > +#define RISCV_IOMMU_REG_IOHPMEVT(_n) (RISCV_IOMMU_REG_IOHPMEVT_BASE + ((_n) * 0x8))
> > +#define RISCV_IOMMU_IOHPMEVT_EVENTID GENMASK_ULL(14, 0)
> > +#define RISCV_IOMMU_IOHPMEVT_DMASK BIT_ULL(15)
> > +#define RISCV_IOMMU_IOHPMEVT_PID_PSCID GENMASK_ULL(35, 16)
> > +#define RISCV_IOMMU_IOHPMEVT_DID_GSCID GENMASK_ULL(59, 36)
> > +#define RISCV_IOMMU_IOHPMEVT_PV_PSCV BIT_ULL(60)
> > +#define RISCV_IOMMU_IOHPMEVT_DV_GSCV BIT_ULL(61)
> > +#define RISCV_IOMMU_IOHPMEVT_IDT BIT_ULL(62)
> > +#define RISCV_IOMMU_IOHPMEVT_OF BIT_ULL(63)
> > +#define RISCV_IOMMU_IOHPMEVT_EVENT GENMASK_ULL(62, 0)
> > +
> > +/* The total number of counters is 31 event counters plus 1 cycle counter */
> > +#define RISCV_IOMMU_HPM_COUNTER_NUM 32
> > +
> > +static int cpuhp_state;
> > +
> > +/**
> > + * enum riscv_iommu_hpmevent_id - Performance-monitoring event identifier
> > + *
> > + * @RISCV_IOMMU_HPMEVENT_CYCLE: Clock cycle counter
> > + * @RISCV_IOMMU_HPMEVENT_URQ: Untranslated requests
> > + * @RISCV_IOMMU_HPMEVENT_TRQ: Translated requests
> > + * @RISCV_IOMMU_HPMEVENT_ATS_RQ: ATS translation requests
> > + * @RISCV_IOMMU_HPMEVENT_TLB_MISS: TLB misses
> > + * @RISCV_IOMMU_HPMEVENT_DD_WALK: Device directory walks
> > + * @RISCV_IOMMU_HPMEVENT_PD_WALK: Process directory walks
> > + * @RISCV_IOMMU_HPMEVENT_S_VS_WALKS: First-stage page table walks
> > + * @RISCV_IOMMU_HPMEVENT_G_WALKS: Second-stage page table walks
> > + * @RISCV_IOMMU_HPMEVENT_MAX: Value to denote maximum Event IDs
> > + *
> > + * The specification does not define an event ID for counting the
> > + * number of clock cycles, meaning there is no associated 'iohpmevt0'.
> > + * Event ID 0 is an invalid event and does not overlap with any valid
> > + * event ID. Let's repurpose ID 0 as the cycle for perf, the cycle
> > + * event is not actually written into any register, it serves solely
> > + * as an identifier.
> > + */
> > +enum riscv_iommu_hpmevent_id {
> > + RISCV_IOMMU_HPMEVENT_CYCLE = 0,
> > + RISCV_IOMMU_HPMEVENT_URQ = 1,
> > + RISCV_IOMMU_HPMEVENT_TRQ = 2,
> > + RISCV_IOMMU_HPMEVENT_ATS_RQ = 3,
> > + RISCV_IOMMU_HPMEVENT_TLB_MISS = 4,
> > + RISCV_IOMMU_HPMEVENT_DD_WALK = 5,
> > + RISCV_IOMMU_HPMEVENT_PD_WALK = 6,
> > + RISCV_IOMMU_HPMEVENT_S_VS_WALKS = 7,
> > + RISCV_IOMMU_HPMEVENT_G_WALKS = 8,
> > + RISCV_IOMMU_HPMEVENT_MAX = 9
> > +};
> > +
> > +struct riscv_iommu_pmu {
> > + struct pmu pmu;
> > + struct hlist_node node;
> > + void __iomem *reg;
> > + unsigned int on_cpu;
> > + int num_counters;
> > + u64 cycle_cntr_mask;
> > + u64 event_cntr_mask;
> > + struct perf_event *events[RISCV_IOMMU_HPM_COUNTER_NUM];
> > + DECLARE_BITMAP(used_counters, RISCV_IOMMU_HPM_COUNTER_NUM);
> > +};
> > +
> > +#define to_riscv_iommu_pmu(p) (container_of(p, struct riscv_iommu_pmu, pmu))
> > +
> > +#define RISCV_IOMMU_PMU_ATTR_EXTRACTOR(_name, _mask) \
> > + static inline u32 get_##_name(struct perf_event *event) \
> > + { \
> > + return FIELD_GET(_mask, event->attr.config); \
> > + } \
> > +
> > +RISCV_IOMMU_PMU_ATTR_EXTRACTOR(event, RISCV_IOMMU_IOHPMEVT_EVENTID);
> > +RISCV_IOMMU_PMU_ATTR_EXTRACTOR(partial_matching, RISCV_IOMMU_IOHPMEVT_DMASK);
> > +RISCV_IOMMU_PMU_ATTR_EXTRACTOR(pid_pscid, RISCV_IOMMU_IOHPMEVT_PID_PSCID);
> > +RISCV_IOMMU_PMU_ATTR_EXTRACTOR(did_gscid, RISCV_IOMMU_IOHPMEVT_DID_GSCID);
> > +RISCV_IOMMU_PMU_ATTR_EXTRACTOR(filter_pid_pscid, RISCV_IOMMU_IOHPMEVT_PV_PSCV);
> > +RISCV_IOMMU_PMU_ATTR_EXTRACTOR(filter_did_gscid, RISCV_IOMMU_IOHPMEVT_DV_GSCV);
> > +RISCV_IOMMU_PMU_ATTR_EXTRACTOR(filter_id_type, RISCV_IOMMU_IOHPMEVT_IDT);
> > +
> > +/* Formats */
> > +PMU_FORMAT_ATTR(event, "config:0-14");
> > +PMU_FORMAT_ATTR(partial_matching, "config:15");
> > +PMU_FORMAT_ATTR(pid_pscid, "config:16-35");
> > +PMU_FORMAT_ATTR(did_gscid, "config:36-59");
> > +PMU_FORMAT_ATTR(filter_pid_pscid, "config:60");
> > +PMU_FORMAT_ATTR(filter_did_gscid, "config:61");
> > +PMU_FORMAT_ATTR(filter_id_type, "config:62");
> > +
> > +static struct attribute *riscv_iommu_pmu_formats[] = {
> > + &format_attr_event.attr,
> > + &format_attr_partial_matching.attr,
> > + &format_attr_pid_pscid.attr,
> > + &format_attr_did_gscid.attr,
> > + &format_attr_filter_pid_pscid.attr,
> > + &format_attr_filter_did_gscid.attr,
> > + &format_attr_filter_id_type.attr,
> > + NULL,
> > +};
> > +
> > +static const struct attribute_group riscv_iommu_pmu_format_group = {
> > + .name = "format",
> > + .attrs = riscv_iommu_pmu_formats,
> > +};
> > +
> > +/* Events */
> > +static ssize_t riscv_iommu_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 sysfs_emit(page, "event=0x%02llx\n", pmu_attr->id);
> > +}
> > +
> > +#define RISCV_IOMMU_PMU_EVENT_ATTR(name, id) \
> > + PMU_EVENT_ATTR_ID(name, riscv_iommu_pmu_event_show, id)
> > +
> > +static struct attribute *riscv_iommu_pmu_events[] = {
> > + RISCV_IOMMU_PMU_EVENT_ATTR(cycle, RISCV_IOMMU_HPMEVENT_CYCLE),
> > + RISCV_IOMMU_PMU_EVENT_ATTR(untranslated_req, RISCV_IOMMU_HPMEVENT_URQ),
> > + RISCV_IOMMU_PMU_EVENT_ATTR(translated_req, RISCV_IOMMU_HPMEVENT_TRQ),
> > + RISCV_IOMMU_PMU_EVENT_ATTR(ats_trans_req, RISCV_IOMMU_HPMEVENT_ATS_RQ),
> > + RISCV_IOMMU_PMU_EVENT_ATTR(tlb_miss, RISCV_IOMMU_HPMEVENT_TLB_MISS),
> > + RISCV_IOMMU_PMU_EVENT_ATTR(ddt_walks, RISCV_IOMMU_HPMEVENT_DD_WALK),
> > + RISCV_IOMMU_PMU_EVENT_ATTR(pdt_walks, RISCV_IOMMU_HPMEVENT_PD_WALK),
> > + RISCV_IOMMU_PMU_EVENT_ATTR(s_vs_pt_walks, RISCV_IOMMU_HPMEVENT_S_VS_WALKS),
> > + RISCV_IOMMU_PMU_EVENT_ATTR(g_pt_walks, RISCV_IOMMU_HPMEVENT_G_WALKS),
> > + NULL,
> > +};
> > +
> > +static const struct attribute_group riscv_iommu_pmu_events_group = {
> > + .name = "events",
> > + .attrs = riscv_iommu_pmu_events,
> > +};
> > +
> > +/* cpumask */
> > +static ssize_t riscv_iommu_cpumask_show(struct device *dev,
> > + struct device_attribute *attr,
> > + char *buf)
> > +{
> > + struct riscv_iommu_pmu *pmu = to_riscv_iommu_pmu(dev_get_drvdata(dev));
> > +
> > + return cpumap_print_to_pagebuf(true, buf, cpumask_of(pmu->on_cpu));
> > +}
> > +
> > +static struct device_attribute riscv_iommu_cpumask_attr =
> > + __ATTR(cpumask, 0444, riscv_iommu_cpumask_show, NULL);
> > +
> > +static struct attribute *riscv_iommu_cpumask_attrs[] = {
> > + &riscv_iommu_cpumask_attr.attr,
> > + NULL
> > +};
> > +
> > +static const struct attribute_group riscv_iommu_pmu_cpumask_group = {
> > + .attrs = riscv_iommu_cpumask_attrs,
> > +};
> > +
> > +static const struct attribute_group *riscv_iommu_pmu_attr_grps[] = {
> > + &riscv_iommu_pmu_cpumask_group,
> > + &riscv_iommu_pmu_format_group,
> > + &riscv_iommu_pmu_events_group,
> > + NULL,
> > +};
> > +
> > +/* PMU Operations */
> > +static void riscv_iommu_pmu_set_counter(struct riscv_iommu_pmu *pmu, u32 idx,
> > + u64 value)
> > +{
> > + u64 counter_mask = idx ? pmu->event_cntr_mask : pmu->cycle_cntr_mask;
> > +
> > + writeq(value & counter_mask, pmu->reg + RISCV_IOMMU_REG_IOHPMCTR(idx));
> > +}
> > +
> > +static u64 riscv_iommu_pmu_get_counter(struct riscv_iommu_pmu *pmu, u32 idx)
> > +{
> > + u64 value, counter_mask = idx ? pmu->event_cntr_mask : pmu->cycle_cntr_mask;
> > +
> > + /* Use readq to read counter would be imprecise on 32-bits system */
> > + value = readq(pmu->reg + RISCV_IOMMU_REG_IOHPMCTR(idx)) & counter_mask;
> As stated in the RISC-V IOMMU Specification, Chapter 6:
> Whether an 8-byte access to an IOMMU register is single-copy atomic is
> UNSPECIFIED, and such an access may appear, internally to the IOMMU,
> as if two separate 4-byte accesses — first to the high half and second
> to the low half — were performed.
>
> Therefore, the atomicity of 64-bit MMIO accesses is UNSPECIFIED and
> not clearly defined in the current ratified RISC-V IOMMU
> specification. To handle this correctly, the Linux RISC-V IOMMU driver
> should fall back to 32-bit MMIO accesses when reading 64-bit HPM counter
> register.
>
> Additionally, David Laight has proposed an optimization using the
> hi-lo-hi read pattern with multiple 32-bit MMIO accesses [1], no retry
> loop.

Hi Guo,
Thanks for your review and suggestion, let me modify it in the next version

>
> [1]: https://lore.kernel.org/linux-riscv/20260618143634.7f3dd6c5@pumpkin/
>
> > +
> > + /* The bit 63 of cycle counter (i.e., idx == 0) is OF bit */
> > + return idx ? value : (value & ~RISCV_IOMMU_IOHPMCYCLES_OF);
> > +}
> > +
> > +static bool is_cycle_event(u64 event)
> > +{
> > + return event == RISCV_IOMMU_HPMEVENT_CYCLE;
> > +}
> > +
> > +static void riscv_iommu_pmu_set_event(struct riscv_iommu_pmu *pmu, u32 idx,
> > + u64 value)
> > +{
> > + /* There is no associtated IOHPMEVT0 for IOHPMCYCLES */
> > + if (is_cycle_event(value))
> > + return;
> > +
> > + /* Event counter start from idx 1 */
> > + writeq(FIELD_GET(RISCV_IOMMU_IOHPMEVT_EVENT, value),
> > + pmu->reg + RISCV_IOMMU_REG_IOHPMEVT(idx - 1));
> > +}
> > +
> > +static void riscv_iommu_pmu_enable_counter(struct riscv_iommu_pmu *pmu, u32 idx)
> > +{
> > + void __iomem *addr = pmu->reg + RISCV_IOMMU_REG_IOCOUNTINH;
> > + u32 value = readl(addr);
> > +
> > + writel(value & ~BIT(idx), addr);
> > +}
> > +
> > +static void riscv_iommu_pmu_disable_counter(struct riscv_iommu_pmu *pmu, u32 idx)
> > +{
> > + void __iomem *addr = pmu->reg + RISCV_IOMMU_REG_IOCOUNTINH;
> > + u32 value = readl(addr);
> > +
> > + writel(value | BIT(idx), addr);
> > +}
> > +
> > +static void riscv_iommu_pmu_start_all(struct riscv_iommu_pmu *pmu)
> > +{
> > + void __iomem *addr = pmu->reg + RISCV_IOMMU_REG_IOCOUNTINH;
> > + u32 used_cntr = 0;
> > +
> > + /* The performance-monitoring counter inhibits is a 32-bit WARL register */
> > + bitmap_to_arr32(&used_cntr, pmu->used_counters, pmu->num_counters);
> > +
> > + writel(~used_cntr, addr);
> > +}
> > +
> > +static void riscv_iommu_pmu_stop_all(struct riscv_iommu_pmu *pmu)
> > +{
> > + writel(GENMASK_ULL(pmu->num_counters - 1, 0),
> > + pmu->reg + RISCV_IOMMU_REG_IOCOUNTINH);
> > +}
> > +
> > +/* PMU APIs */
> > +static void riscv_iommu_pmu_set_period(struct perf_event *event)
> > +{
> > + struct riscv_iommu_pmu *pmu = to_riscv_iommu_pmu(event->pmu);
> > + struct hw_perf_event *hwc = &event->hw;
> > + u64 counter_mask = hwc->idx ? pmu->event_cntr_mask : pmu->cycle_cntr_mask;
> > + u64 period;
> > +
> > + /*
> > + * Limit the maximum period to prevent the counter value
> > + * from overtaking the one we are about to program.
> > + * In effect we are reducing max_period to account for
> > + * interrupt latency (and we are being very conservative).
> > + */
> > + period = counter_mask >> 1;
> > + riscv_iommu_pmu_set_counter(pmu, hwc->idx, period);
> > + local64_set(&hwc->prev_count, period);
> > +}
> > +
> > +static int riscv_iommu_pmu_event_init(struct perf_event *event)
> > +{
> > + struct riscv_iommu_pmu *pmu = to_riscv_iommu_pmu(event->pmu);
> > + struct hw_perf_event *hwc = &event->hw;
> > + struct perf_event *sibling;
> > + int total_event_counters = pmu->num_counters - 1;
> > + int counters = 0;
> > +
> > + if (event->attr.type != event->pmu->type)
> > + return -ENOENT;
> > +
> > + if (hwc->sample_period)
> > + return -EOPNOTSUPP;
> > +
> > + if (event->cpu < 0)
> > + return -EOPNOTSUPP;
> > +
> > + event->cpu = pmu->on_cpu;
> > +
> > + hwc->idx = -1;
> > + hwc->config = event->attr.config;
> > +
> > + if (event->group_leader == event)
> > + return 0;
> > +
> > + if (is_cycle_event(get_event(event->group_leader)))
> > + if (++counters > total_event_counters)
> > + return -EINVAL;
> > +
> > + for_each_sibling_event(sibling, event->group_leader) {
> > + if (is_cycle_event(get_event(sibling)))
> > + continue;
> > +
> > + if (sibling->pmu != event->pmu && !is_software_event(sibling))
> > + return -EINVAL;
> > +
> > + if (++counters > total_event_counters)
> > + return -EINVAL;
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static void riscv_iommu_pmu_update(struct perf_event *event)
> > +{
> > + struct hw_perf_event *hwc = &event->hw;
> > + struct riscv_iommu_pmu *pmu = to_riscv_iommu_pmu(event->pmu);
> > + u64 delta, prev, now;
> > + u32 idx = hwc->idx;
> > + u64 counter_mask = idx ? pmu->event_cntr_mask : pmu->cycle_cntr_mask;
> > +
> > + do {
> > + prev = local64_read(&hwc->prev_count);
> > + now = riscv_iommu_pmu_get_counter(pmu, idx);
> > + } while (local64_cmpxchg(&hwc->prev_count, prev, now) != prev);
> > +
> > + delta = (now - prev) & counter_mask;
> > + local64_add(delta, &event->count);
> > +}
> > +
> > +static void riscv_iommu_pmu_start(struct perf_event *event, int flags)
> > +{
> > + struct riscv_iommu_pmu *pmu = to_riscv_iommu_pmu(event->pmu);
> > + struct hw_perf_event *hwc = &event->hw;
> > +
> > + if (WARN_ON_ONCE(!(event->hw.state & PERF_HES_STOPPED)))
> > + return;
> > +
> > + if (flags & PERF_EF_RELOAD)
> > + WARN_ON_ONCE(!(event->hw.state & PERF_HES_UPTODATE));
> > +
> > + hwc->state = 0;
> > + riscv_iommu_pmu_set_period(event);
> > + riscv_iommu_pmu_set_event(pmu, hwc->idx, hwc->config);
> > + riscv_iommu_pmu_enable_counter(pmu, hwc->idx);
> > +
> > + perf_event_update_userpage(event);
> > +}
> > +
> > +static void riscv_iommu_pmu_stop(struct perf_event *event, int flags)
> > +{
> > + struct riscv_iommu_pmu *pmu = to_riscv_iommu_pmu(event->pmu);
> > + struct hw_perf_event *hwc = &event->hw;
> > + int idx = hwc->idx;
> > +
> > + if (hwc->state & PERF_HES_STOPPED)
> > + return;
> > +
> > + riscv_iommu_pmu_disable_counter(pmu, idx);
> > +
> > + if ((flags & PERF_EF_UPDATE) && !(hwc->state & PERF_HES_UPTODATE))
> > + riscv_iommu_pmu_update(event);
> > +
> > + hwc->state |= PERF_HES_STOPPED | PERF_HES_UPTODATE;
> > +}
> > +
> > +static int riscv_iommu_pmu_add(struct perf_event *event, int flags)
> > +{
> > + struct riscv_iommu_pmu *pmu = to_riscv_iommu_pmu(event->pmu);
> > + struct hw_perf_event *hwc = &event->hw;
> > + unsigned int num_counters = pmu->num_counters;
> > + int idx;
> > +
> > + /* Reserve index zero for iohpmcycles */
> > + if (is_cycle_event(get_event(event)))
> > + idx = 0;
> > + else
> > + idx = find_next_zero_bit(pmu->used_counters, num_counters, 1);
> > +
> > + /* All event counters or cycle counter are in use */
> > + if (idx == num_counters || pmu->events[idx])
> > + return -EAGAIN;
> > +
> > + set_bit(idx, pmu->used_counters);
> > +
> > + pmu->events[idx] = event;
> > + hwc->idx = idx;
> > + hwc->state = PERF_HES_STOPPED | PERF_HES_UPTODATE;
> > + local64_set(&hwc->prev_count, 0);
> > +
> > + if (flags & PERF_EF_START)
> > + riscv_iommu_pmu_start(event, flags);
> > +
> > + /* Propagate changes to the userspace mapping. */
> > + perf_event_update_userpage(event);
> > +
> > + return 0;
> > +}
> > +
> > +static void riscv_iommu_pmu_read(struct perf_event *event)
> > +{
> > + riscv_iommu_pmu_update(event);
> > +}
> > +
> > +static void riscv_iommu_pmu_del(struct perf_event *event, int flags)
> > +{
> > + struct riscv_iommu_pmu *pmu = to_riscv_iommu_pmu(event->pmu);
> > + struct hw_perf_event *hwc = &event->hw;
> > + int idx = hwc->idx;
> > +
> > + riscv_iommu_pmu_stop(event, PERF_EF_UPDATE);
> > + pmu->events[idx] = NULL;
> > + clear_bit(idx, pmu->used_counters);
> > +
> > + perf_event_update_userpage(event);
> > +}
> > +
> > +static int riscv_iommu_pmu_online_cpu(unsigned int cpu, struct hlist_node *node)
> > +{
> > + struct riscv_iommu_pmu *iommu_pmu;
> > +
> > + iommu_pmu = hlist_entry_safe(node, struct riscv_iommu_pmu, node);
> > +
> > + if (iommu_pmu->on_cpu == -1)
> > + iommu_pmu->on_cpu = cpu;
> > +
> > + return 0;
> > +}
> > +
> > +static int riscv_iommu_pmu_offline_cpu(unsigned int cpu, struct hlist_node *node)
> > +{
> > + struct riscv_iommu_pmu *iommu_pmu;
> > + unsigned int target_cpu;
> > +
> > + iommu_pmu = hlist_entry_safe(node, struct riscv_iommu_pmu, node);
> > +
> > + if (cpu != iommu_pmu->on_cpu)
> > + return 0;
> > +
> > + iommu_pmu->on_cpu = -1;
> > +
> > + target_cpu = cpumask_any_but(cpu_online_mask, cpu);
> > + if (target_cpu >= nr_cpu_ids)
> > + return 0;
> > +
> > + perf_pmu_migrate_context(&iommu_pmu->pmu, cpu, target_cpu);
> > + iommu_pmu->on_cpu = target_cpu;
> > +
> > + return 0;
> > +}
> > +
> > +static irqreturn_t riscv_iommu_pmu_handle_irq(struct riscv_iommu_pmu *pmu)
> > +{
> > + u32 ovf = readl(pmu->reg + RISCV_IOMMU_REG_IOCOUNTOVF);
> > + int idx;
> > +
> > + if (!ovf)
> > + return IRQ_NONE;
> > +
> > + riscv_iommu_pmu_stop_all(pmu);
> > +
> > + for_each_set_bit(idx, (unsigned long *)&ovf, pmu->num_counters) {
> > + struct perf_event *event = pmu->events[idx];
> > +
> > + if (WARN_ON_ONCE(!event))
> > + continue;
> > +
> > + riscv_iommu_pmu_update(event);
> > + riscv_iommu_pmu_set_period(event);
> > + }
> > +
> > + riscv_iommu_pmu_start_all(pmu);
> > +
> > + return IRQ_HANDLED;
> > +}
> > +
> > +static irqreturn_t riscv_iommu_pmu_irq_handler(int irq, void *dev_id)
> > +{
> > + struct riscv_iommu_pmu *pmu = (struct riscv_iommu_pmu *)dev_id;
> > + irqreturn_t ret;
> > +
> > + /* Check whether this interrupt is for PMU */
> > + if (!(readl_relaxed(pmu->reg + RISCV_IOMMU_REG_IPSR) & RISCV_IOMMU_IPSR_PMIP))
> > + return IRQ_NONE;
> > +
> > + /* Process PMU IRQ */
> > + ret = riscv_iommu_pmu_handle_irq(pmu);
> > +
> > + /* Clear performance monitoring interrupt pending bit */
> > + writel_relaxed(RISCV_IOMMU_IPSR_PMIP, pmu->reg + RISCV_IOMMU_REG_IPSR);
> > +
> > + return ret;
> > +}
> > +
> > +static unsigned int riscv_iommu_pmu_get_irq_num(struct riscv_iommu_device *iommu)
> > +{
> > + /* Reuse ICVEC.CIV mask for all interrupt vectors mapping */
> > + int vec = (iommu->icvec >> (RISCV_IOMMU_IPSR_PMIP * 4)) & RISCV_IOMMU_ICVEC_CIV;
> > +
> > + return iommu->irqs[vec];
> > +}
> > +
> > +static int riscv_iommu_pmu_request_irq(struct riscv_iommu_device *iommu,
> > + struct riscv_iommu_pmu *pmu)
> > +{
> > + unsigned int irq = riscv_iommu_pmu_get_irq_num(iommu);
> > +
> > + /*
> > + * Set the IRQF_ONESHOT flag because this IRQ can be shared with
> > + * other threaded IRQs by other queues.
> > + */
> > + return devm_request_irq(iommu->dev, irq, riscv_iommu_pmu_irq_handler,
> > + IRQF_ONESHOT | IRQF_SHARED, dev_name(iommu->dev), pmu);
> > +}
> > +
> > +static void riscv_iommu_pmu_free_irq(struct riscv_iommu_device *iommu,
> > + struct riscv_iommu_pmu *pmu)
> > +{
> > + unsigned int irq = riscv_iommu_pmu_get_irq_num(iommu);
> > +
> > + free_irq(irq, pmu);
> > +}
> > +
> > +static int riscv_iommu_pmu_probe(struct auxiliary_device *auxdev,
> > + const struct auxiliary_device_id *id)
> > +{
> > + struct riscv_iommu_device *iommu_dev = dev_get_platdata(&auxdev->dev);
> > + struct riscv_iommu_pmu *iommu_pmu;
> > + void __iomem *addr;
> > + char *name;
> > + int ret;
> > +
> > + iommu_pmu = devm_kzalloc(&auxdev->dev, sizeof(*iommu_pmu), GFP_KERNEL);
> > + if (!iommu_pmu)
> > + return -ENOMEM;
> > +
> > + iommu_pmu->reg = iommu_dev->reg;
> > +
> > + /* Counter number and width are hardware-implemented. Detect them by write 1s */
> > + addr = iommu_pmu->reg + RISCV_IOMMU_REG_IOCOUNTINH;
> > + writel(RISCV_IOMMU_IOCOUNTINH_HPM, addr);
> > + iommu_pmu->num_counters = hweight32(readl(addr));
> > +
> > + addr = iommu_pmu->reg + RISCV_IOMMU_REG_IOHPMCYCLES;
> > + writeq(RISCV_IOMMU_IOHPMCYCLES_COUNTER, addr);
> > + iommu_pmu->cycle_cntr_mask = readq(addr);
> > +
> > + /* Assume the width of all event counters are the same */
> > + addr = iommu_pmu->reg + RISCV_IOMMU_REG_IOHPMCTR_BASE;
> > + writeq(RISCV_IOMMU_IOHPMCTR_COUNTER, addr);
> > + iommu_pmu->event_cntr_mask = readq(addr);
> > +
> > + iommu_pmu->pmu = (struct pmu) {
> > + .module = THIS_MODULE,
> > + .parent = &auxdev->dev,
> > + .task_ctx_nr = perf_invalid_context,
> > + .event_init = riscv_iommu_pmu_event_init,
> > + .add = riscv_iommu_pmu_add,
> > + .del = riscv_iommu_pmu_del,
> > + .start = riscv_iommu_pmu_start,
> > + .stop = riscv_iommu_pmu_stop,
> > + .read = riscv_iommu_pmu_read,
> > + .attr_groups = riscv_iommu_pmu_attr_grps,
> > + .capabilities = PERF_PMU_CAP_NO_EXCLUDE,
> > + };
> > +
> > + auxiliary_set_drvdata(auxdev, iommu_pmu);
> > +
> > + name = devm_kasprintf(&auxdev->dev, GFP_KERNEL,
> > + "riscv_iommu_pmu_%s", dev_name(iommu_dev->dev));
> > + if (!name) {
> > + dev_err(&auxdev->dev, "Failed to create name riscv_iommu_pmu_%s\n",
> > + dev_name(iommu_dev->dev));
> > + return -ENOMEM;
> > + }
> > +
> > + /* Bind all events to the same cpu context to avoid race enabling */
> > + iommu_pmu->on_cpu = raw_smp_processor_id();
> > +
> > + ret = cpuhp_state_add_instance_nocalls(cpuhp_state, &iommu_pmu->node);
> > + if (ret) {
> > + dev_err(&auxdev->dev, "Failed to register hotplug %s: %d\n", name, ret);
> > + return ret;
> > + }
> > +
> > + ret = riscv_iommu_pmu_request_irq(iommu_dev, iommu_pmu);
> > + if (ret) {
> > + dev_err(&auxdev->dev, "Failed to request irq %s: %d\n", name, ret);
> > + goto err_cpuhp_remove;
> > + }
> > +
> > + ret = perf_pmu_register(&iommu_pmu->pmu, name, -1);
> > + if (ret) {
> > + dev_err(&auxdev->dev, "Failed to registe %s: %d\n", name, ret);
> > + goto err_free_irq;
> > + }
> > +
> > + dev_info(&auxdev->dev, "%s: Registered with %d counters\n",
> > + name, iommu_pmu->num_counters);
> > +
> > + return 0;
> > +
> > +err_free_irq:
> > + riscv_iommu_pmu_free_irq(iommu_dev, iommu_pmu);
> > +err_cpuhp_remove:
> > + cpuhp_state_remove_instance_nocalls(cpuhp_state, &iommu_pmu->node);
> > + return ret;
> > +}
> > +
> > +static const struct auxiliary_device_id riscv_iommu_pmu_id_table[] = {
> > + { .name = "iommu.pmu" },
> > + {}
> > +};
> > +MODULE_DEVICE_TABLE(auxiliary, riscv_iommu_pmu_id_table);
> > +
> > +static struct auxiliary_driver iommu_pmu_driver = {
> > + .probe = riscv_iommu_pmu_probe,
> > + .id_table = riscv_iommu_pmu_id_table,
> > +};
> > +
> > +static int __init riscv_iommu_pmu_init(void)
> > +{
> > + int ret;
> > +
> > + cpuhp_state = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN,
> > + "perf/riscv/iommu:online",
> > + riscv_iommu_pmu_online_cpu,
> > + riscv_iommu_pmu_offline_cpu);
> > + if (cpuhp_state < 0)
> > + return cpuhp_state;
> > +
> > + ret = auxiliary_driver_register(&iommu_pmu_driver);
> > + if (ret)
> > + cpuhp_remove_multi_state(cpuhp_state);
> > +
> > + return ret;
> > +}
> > +module_init(riscv_iommu_pmu_init);
> > +
> > +MODULE_DESCRIPTION("RISC-V IOMMU PMU");
> > +MODULE_LICENSE("GPL");
> > --
> > 2.43.7
> >
> >
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> >