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References: <20230531110011.13963-1-Jonathan.Cameron@huawei.com> <20230531110011.13963-5-Jonathan.Cameron@huawei.com>
In-Reply-To: <20230531110011.13963-5-Jonathan.Cameron@huawei.com>
From:   Namhyung Kim <namhyung@kernel.org>
Date:   Wed, 31 May 2023 11:00:00 -0700
Message-ID: <CAM9d7chdOGqznswMgdavMTc79+62A4FxEy8-HvJAkQa4WQnrVA@mail.gmail.com>
Subject: Re: [PATCH v8 4/5] perf: CXL Performance Monitoring Unit driver
To:     Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc:     Liang Kan <kan.liang@linux.intel.com>, linux-cxl@vger.kernel.org,
        peterz@infradead.org, mingo@reresetdhat.com, acme@kernel.org,
        mark.rutland@arm.com, will@kernel.org, dan.j.williams@intel.com,
        linuxarm@huawei.com, linux-perf-users@vger.kernel.org,
        linux-kernel@vger.kernel.org, Davidlohr Bueso <dave@stgolabs.net>,
        Dave Jiang <dave.jiang@intel.com>
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Precedence: bulk

Hello,

On Wed, May 31, 2023 at 4:02 AM Jonathan Cameron
<Jonathan.Cameron@huawei.com> wrote:
>
> CXL rev 3.0 introduces a standard performance monitoring hardware
> block to CXL. Instances are discovered using CXL Register Locator DVSEC
> entries. Each CXL component may have multiple PMUs.
>
> This initial driver supports a subset of types of counter.
> It supports counters that are either fixed or configurable, but requires
> that they support the ability to freeze and write value whilst frozen.
>
> Development done with QEMU model which will be posted shortly.
>
> Example:
>
> $ perf stat -a -e cxl_pmu_mem0.0/h2d_req_snpcur/ -e cxl_pmu_mem0.0/h2d_req_snpdata/ -e cxl_pmu_mem0.0/clock_ticks/ sleep 1
>
> Performance counter stats for 'system wide':
>
> 96,757,023,244,321      cxl_pmu_mem0.0/h2d_req_snpcur/
> 96,757,023,244,365      cxl_pmu_mem0.0/h2d_req_snpdata/
> 193,514,046,488,653      cxl_pmu_mem0.0/clock_ticks/
>
>        1.090539600 seconds time elapsed
>
> Reviewed-by: Dave Jiang <dave.jiang@intel.com>
> Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Acked-by: Namhyung Kim <namhyung@kernel.org>

Thanks,
Namhyung


> ---
> v8: Comment typo fixes.
> ---
>  MAINTAINERS            |   6 +
>  drivers/cxl/Kconfig    |  13 +
>  drivers/perf/Kconfig   |  13 +
>  drivers/perf/Makefile  |   1 +
>  drivers/perf/cxl_pmu.c | 990 +++++++++++++++++++++++++++++++++++++++++
>  5 files changed, 1023 insertions(+)
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index e0ad886d3163..976b3e982d3a 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -5191,6 +5191,12 @@ S:       Maintained
>  F:     drivers/cxl/
>  F:     include/uapi/linux/cxl_mem.h
>
> +COMPUTE EXPRESS LINK PMU (CPMU)
> +M:     Jonathan Cameron <jonathan.cameron@huawei.com>
> +L:     linux-cxl@vger.kernel.org
> +S:     Maintained
> +F:     drivers/perf/cxl_pmu.c
> +
>  CONEXANT ACCESSRUNNER USB DRIVER
>  L:     accessrunner-general@lists.sourceforge.net
>  S:     Orphan
> diff --git a/drivers/cxl/Kconfig b/drivers/cxl/Kconfig
> index ff4e78117b31..d0a4b4cfa50c 100644
> --- a/drivers/cxl/Kconfig
> +++ b/drivers/cxl/Kconfig
> @@ -139,4 +139,17 @@ config CXL_REGION_INVALIDATION_TEST
>           If unsure, or if this kernel is meant for production environments,
>           say N.
>
> +config CXL_PMU
> +       tristate "CXL Performance Monitoring Unit"
> +       default CXL_BUS
> +       depends on PERF_EVENTS
> +       help
> +         Support performance monitoring as defined in CXL rev 3.0
> +         section 13.2: Performance Monitoring. CXL components may have
> +         one or more CXL Performance Monitoring Units (CPMUs).
> +
> +         Say 'y/m' to enable a driver that will attach to performance
> +         monitoring units and provide standard perf based interfaces.
> +
> +         If unsure say 'm'.
>  endif
> diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig
> index 711f82400086..2d2dd400fed2 100644
> --- a/drivers/perf/Kconfig
> +++ b/drivers/perf/Kconfig
> @@ -213,4 +213,17 @@ source "drivers/perf/arm_cspmu/Kconfig"
>
>  source "drivers/perf/amlogic/Kconfig"
>
> +config CXL_PMU
> +       tristate "CXL Performance Monitoring Unit"
> +       depends on CXL_BUS
> +       help
> +         Support performance monitoring as defined in CXL rev 3.0
> +         section 13.2: Performance Monitoring. CXL components may have
> +         one or more CXL Performance Monitoring Units (CPMUs).
> +
> +         Say 'y/m' to enable a driver that will attach to performance
> +         monitoring units and provide standard perf based interfaces.
> +
> +         If unsure say 'm'.
> +
>  endmenu
> diff --git a/drivers/perf/Makefile b/drivers/perf/Makefile
> index dabc859540ce..f1d7ce9da275 100644
> --- a/drivers/perf/Makefile
> +++ b/drivers/perf/Makefile
> @@ -24,3 +24,4 @@ obj-$(CONFIG_APPLE_M1_CPU_PMU) += apple_m1_cpu_pmu.o
>  obj-$(CONFIG_ALIBABA_UNCORE_DRW_PMU) += alibaba_uncore_drw_pmu.o
>  obj-$(CONFIG_ARM_CORESIGHT_PMU_ARCH_SYSTEM_PMU) += arm_cspmu/
>  obj-$(CONFIG_MESON_DDR_PMU) += amlogic/
> +obj-$(CONFIG_CXL_PMU) += cxl_pmu.o
> diff --git a/drivers/perf/cxl_pmu.c b/drivers/perf/cxl_pmu.c
> new file mode 100644
> index 000000000000..47f2eb21facb
> --- /dev/null
> +++ b/drivers/perf/cxl_pmu.c
> @@ -0,0 +1,990 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +
> +/*
> + * Copyright(c) 2023 Huawei
> + *
> + * The CXL 3.0 specification includes a standard Performance Monitoring Unit,
> + * called the CXL PMU, or CPMU. In order to allow a high degree of
> + * implementation flexibility the specification provides a wide range of
> + * options all of which are self describing.
> + *
> + * Details in CXL rev 3.0 section 8.2.7 CPMU Register Interface
> + */
> +
> +#include <linux/io-64-nonatomic-lo-hi.h>
> +#include <linux/perf_event.h>
> +#include <linux/bitops.h>
> +#include <linux/device.h>
> +#include <linux/bits.h>
> +#include <linux/list.h>
> +#include <linux/bug.h>
> +#include <linux/pci.h>
> +
> +#include "../cxl/cxlpci.h"
> +#include "../cxl/cxl.h"
> +#include "../cxl/pmu.h"
> +
> +#define CXL_PMU_CAP_REG                        0x0
> +#define   CXL_PMU_CAP_NUM_COUNTERS_MSK                 GENMASK_ULL(4, 0)
> +#define   CXL_PMU_CAP_COUNTER_WIDTH_MSK                        GENMASK_ULL(15, 8)
> +#define   CXL_PMU_CAP_NUM_EVN_CAP_REG_SUP_MSK          GENMASK_ULL(24, 20)
> +#define   CXL_PMU_CAP_FILTERS_SUP_MSK                  GENMASK_ULL(39, 32)
> +#define     CXL_PMU_FILTER_HDM                         BIT(0)
> +#define     CXL_PMU_FILTER_CHAN_RANK_BANK              BIT(1)
> +#define   CXL_PMU_CAP_MSI_N_MSK                                GENMASK_ULL(47, 44)
> +#define   CXL_PMU_CAP_WRITEABLE_WHEN_FROZEN            BIT_ULL(48)
> +#define   CXL_PMU_CAP_FREEZE                           BIT_ULL(49)
> +#define   CXL_PMU_CAP_INT                              BIT_ULL(50)
> +#define   CXL_PMU_CAP_VERSION_MSK                      GENMASK_ULL(63, 60)
> +
> +#define CXL_PMU_OVERFLOW_REG           0x10
> +#define CXL_PMU_FREEZE_REG             0x18
> +#define CXL_PMU_EVENT_CAP_REG(n)       (0x100 + 8 * (n))
> +#define   CXL_PMU_EVENT_CAP_SUPPORTED_EVENTS_MSK       GENMASK_ULL(31, 0)
> +#define   CXL_PMU_EVENT_CAP_GROUP_ID_MSK               GENMASK_ULL(47, 32)
> +#define   CXL_PMU_EVENT_CAP_VENDOR_ID_MSK              GENMASK_ULL(63, 48)
> +
> +#define CXL_PMU_COUNTER_CFG_REG(n)     (0x200 + 8 * (n))
> +#define   CXL_PMU_COUNTER_CFG_TYPE_MSK                 GENMASK_ULL(1, 0)
> +#define     CXL_PMU_COUNTER_CFG_TYPE_FREE_RUN          0
> +#define     CXL_PMU_COUNTER_CFG_TYPE_FIXED_FUN         1
> +#define     CXL_PMU_COUNTER_CFG_TYPE_CONFIGURABLE      2
> +#define   CXL_PMU_COUNTER_CFG_ENABLE                   BIT_ULL(8)
> +#define   CXL_PMU_COUNTER_CFG_INT_ON_OVRFLW            BIT_ULL(9)
> +#define   CXL_PMU_COUNTER_CFG_FREEZE_ON_OVRFLW         BIT_ULL(10)
> +#define   CXL_PMU_COUNTER_CFG_EDGE                     BIT_ULL(11)
> +#define   CXL_PMU_COUNTER_CFG_INVERT                   BIT_ULL(12)
> +#define   CXL_PMU_COUNTER_CFG_THRESHOLD_MSK            GENMASK_ULL(23, 16)
> +#define   CXL_PMU_COUNTER_CFG_EVENTS_MSK               GENMASK_ULL(55, 24)
> +#define   CXL_PMU_COUNTER_CFG_EVENT_GRP_ID_IDX_MSK     GENMASK_ULL(63, 59)
> +
> +#define CXL_PMU_FILTER_CFG_REG(n, f)   (0x400 + 4 * ((f) + (n) * 8))
> +#define   CXL_PMU_FILTER_CFG_VALUE_MSK                 GENMASK(15, 0)
> +
> +#define CXL_PMU_COUNTER_REG(n)         (0xc00 + 8 * (n))
> +
> +/* CXL rev 3.0 Table 13-5 Events under CXL Vendor ID */
> +#define CXL_PMU_GID_CLOCK_TICKS                0x00
> +#define CXL_PMU_GID_D2H_REQ            0x0010
> +#define CXL_PMU_GID_D2H_RSP            0x0011
> +#define CXL_PMU_GID_H2D_REQ            0x0012
> +#define CXL_PMU_GID_H2D_RSP            0x0013
> +#define CXL_PMU_GID_CACHE_DATA         0x0014
> +#define CXL_PMU_GID_M2S_REQ            0x0020
> +#define CXL_PMU_GID_M2S_RWD            0x0021
> +#define CXL_PMU_GID_M2S_BIRSP          0x0022
> +#define CXL_PMU_GID_S2M_BISNP          0x0023
> +#define CXL_PMU_GID_S2M_NDR            0x0024
> +#define CXL_PMU_GID_S2M_DRS            0x0025
> +#define CXL_PMU_GID_DDR                        0x8000
> +
> +static int cxl_pmu_cpuhp_state_num;
> +
> +struct cxl_pmu_ev_cap {
> +       u16 vid;
> +       u16 gid;
> +       u32 msk;
> +       union {
> +               int counter_idx; /* fixed counters */
> +               int event_idx; /* configurable counters */
> +       };
> +       struct list_head node;
> +};
> +
> +#define CXL_PMU_MAX_COUNTERS 64
> +struct cxl_pmu_info {
> +       struct pmu pmu;
> +       void __iomem *base;
> +       struct perf_event **hw_events;
> +       struct list_head event_caps_configurable;
> +       struct list_head event_caps_fixed;
> +       DECLARE_BITMAP(used_counter_bm, CXL_PMU_MAX_COUNTERS);
> +       DECLARE_BITMAP(conf_counter_bm, CXL_PMU_MAX_COUNTERS);
> +       u16 counter_width;
> +       u8 num_counters;
> +       u8 num_event_capabilities;
> +       int on_cpu;
> +       struct hlist_node node;
> +       bool filter_hdm;
> +       int irq;
> +};
> +
> +#define pmu_to_cxl_pmu_info(_pmu) container_of(_pmu, struct cxl_pmu_info, pmu)
> +
> +/*
> + * All CPMU counters are discoverable via the Event Capabilities Registers.
> + * Each Event Capability register contains a a VID / GroupID.
> + * A counter may then count any combination (by summing) of events in
> + * that group which are in the Supported Events Bitmask.
> + * However, there are some complexities to the scheme.
> + *  - Fixed function counters refer to an Event Capabilities register.
> + *    That event capability register is not then used for Configurable
> + *    counters.
> + */
> +static int cxl_pmu_parse_caps(struct device *dev, struct cxl_pmu_info *info)
> +{
> +       unsigned long fixed_counter_event_cap_bm = 0;
> +       void __iomem *base = info->base;
> +       bool freeze_for_enable;
> +       u64 val, eval;
> +       int i;
> +
> +       val = readq(base + CXL_PMU_CAP_REG);
> +       freeze_for_enable = FIELD_GET(CXL_PMU_CAP_WRITEABLE_WHEN_FROZEN, val) &&
> +               FIELD_GET(CXL_PMU_CAP_FREEZE, val);
> +       if (!freeze_for_enable) {
> +               dev_err(dev, "Counters not writable while frozen\n");
> +               return -ENODEV;
> +       }
> +
> +       info->num_counters = FIELD_GET(CXL_PMU_CAP_NUM_COUNTERS_MSK, val) + 1;
> +       info->counter_width = FIELD_GET(CXL_PMU_CAP_COUNTER_WIDTH_MSK, val);
> +       info->num_event_capabilities = FIELD_GET(CXL_PMU_CAP_NUM_EVN_CAP_REG_SUP_MSK, val) + 1;
> +
> +       info->filter_hdm = FIELD_GET(CXL_PMU_CAP_FILTERS_SUP_MSK, val) & CXL_PMU_FILTER_HDM;
> +       if (FIELD_GET(CXL_PMU_CAP_INT, val))
> +               info->irq = FIELD_GET(CXL_PMU_CAP_MSI_N_MSK, val);
> +       else
> +               info->irq = -1;
> +
> +       /* First handle fixed function counters; note if configurable counters found */
> +       for (i = 0; i < info->num_counters; i++) {
> +               struct cxl_pmu_ev_cap *pmu_ev;
> +               u32 events_msk;
> +               u8 group_idx;
> +
> +               val = readq(base + CXL_PMU_COUNTER_CFG_REG(i));
> +
> +               if (FIELD_GET(CXL_PMU_COUNTER_CFG_TYPE_MSK, val) ==
> +                       CXL_PMU_COUNTER_CFG_TYPE_CONFIGURABLE) {
> +                       set_bit(i, info->conf_counter_bm);
> +               }
> +
> +               if (FIELD_GET(CXL_PMU_COUNTER_CFG_TYPE_MSK, val) !=
> +                   CXL_PMU_COUNTER_CFG_TYPE_FIXED_FUN)
> +                       continue;
> +
> +               /* In this case we know which fields are const */
> +               group_idx = FIELD_GET(CXL_PMU_COUNTER_CFG_EVENT_GRP_ID_IDX_MSK, val);
> +               events_msk = FIELD_GET(CXL_PMU_COUNTER_CFG_EVENTS_MSK, val);
> +               eval = readq(base + CXL_PMU_EVENT_CAP_REG(group_idx));
> +               pmu_ev = devm_kzalloc(dev, sizeof(*pmu_ev), GFP_KERNEL);
> +               if (!pmu_ev)
> +                       return -ENOMEM;
> +
> +               pmu_ev->vid = FIELD_GET(CXL_PMU_EVENT_CAP_VENDOR_ID_MSK, eval);
> +               pmu_ev->gid = FIELD_GET(CXL_PMU_EVENT_CAP_GROUP_ID_MSK, eval);
> +               /* For a fixed purpose counter use the events mask from the counter CFG */
> +               pmu_ev->msk = events_msk;
> +               pmu_ev->counter_idx = i;
> +               /* This list add is never unwound as all entries deleted on remove */
> +               list_add(&pmu_ev->node, &info->event_caps_fixed);
> +               /*
> +                * Configurable counters must not use an Event Capability registers that
> +                * is in use for a Fixed counter
> +                */
> +               set_bit(group_idx, &fixed_counter_event_cap_bm);
> +       }
> +
> +       if (!bitmap_empty(info->conf_counter_bm, CXL_PMU_MAX_COUNTERS)) {
> +               struct cxl_pmu_ev_cap *pmu_ev;
> +               int j;
> +               /* Walk event capabilities unused by fixed counters */
> +               for_each_clear_bit(j, &fixed_counter_event_cap_bm,
> +                                  info->num_event_capabilities) {
> +                       pmu_ev = devm_kzalloc(dev, sizeof(*pmu_ev), GFP_KERNEL);
> +                       if (!pmu_ev)
> +                               return -ENOMEM;
> +
> +                       eval = readq(base + CXL_PMU_EVENT_CAP_REG(j));
> +                       pmu_ev->vid = FIELD_GET(CXL_PMU_EVENT_CAP_VENDOR_ID_MSK, eval);
> +                       pmu_ev->gid = FIELD_GET(CXL_PMU_EVENT_CAP_GROUP_ID_MSK, eval);
> +                       pmu_ev->msk = FIELD_GET(CXL_PMU_EVENT_CAP_SUPPORTED_EVENTS_MSK, eval);
> +                       pmu_ev->event_idx = j;
> +                       list_add(&pmu_ev->node, &info->event_caps_configurable);
> +               }
> +       }
> +
> +       return 0;
> +}
> +
> +static ssize_t cxl_pmu_format_sysfs_show(struct device *dev,
> +                                        struct device_attribute *attr, char *buf)
> +{
> +       struct dev_ext_attribute *eattr;
> +
> +       eattr = container_of(attr, struct dev_ext_attribute, attr);
> +
> +       return sysfs_emit(buf, "%s\n", (char *)eattr->var);
> +}
> +
> +#define CXL_PMU_FORMAT_ATTR(_name, _format)\
> +       (&((struct dev_ext_attribute[]) {                                       \
> +               {                                                               \
> +                       .attr = __ATTR(_name, 0444,                             \
> +                                      cxl_pmu_format_sysfs_show, NULL),        \
> +                       .var = (void *)_format                                  \
> +               }                                                               \
> +               })[0].attr.attr)
> +
> +enum {
> +       cxl_pmu_mask_attr,
> +       cxl_pmu_gid_attr,
> +       cxl_pmu_vid_attr,
> +       cxl_pmu_threshold_attr,
> +       cxl_pmu_invert_attr,
> +       cxl_pmu_edge_attr,
> +       cxl_pmu_hdm_filter_en_attr,
> +       cxl_pmu_hdm_attr,
> +};
> +
> +static struct attribute *cxl_pmu_format_attr[] = {
> +       [cxl_pmu_mask_attr] = CXL_PMU_FORMAT_ATTR(mask, "config:0-31"),
> +       [cxl_pmu_gid_attr] = CXL_PMU_FORMAT_ATTR(gid, "config:32-47"),
> +       [cxl_pmu_vid_attr] = CXL_PMU_FORMAT_ATTR(vid, "config:48-63"),
> +       [cxl_pmu_threshold_attr] = CXL_PMU_FORMAT_ATTR(threshold, "config1:0-15"),
> +       [cxl_pmu_invert_attr] = CXL_PMU_FORMAT_ATTR(invert, "config1:16"),
> +       [cxl_pmu_edge_attr] = CXL_PMU_FORMAT_ATTR(edge, "config1:17"),
> +       [cxl_pmu_hdm_filter_en_attr] = CXL_PMU_FORMAT_ATTR(hdm_filter_en, "config1:18"),
> +       [cxl_pmu_hdm_attr] = CXL_PMU_FORMAT_ATTR(hdm, "config2:0-15"),
> +       NULL
> +};
> +
> +#define CXL_PMU_ATTR_CONFIG_MASK_MSK           GENMASK_ULL(31, 0)
> +#define CXL_PMU_ATTR_CONFIG_GID_MSK            GENMASK_ULL(47, 32)
> +#define CXL_PMU_ATTR_CONFIG_VID_MSK            GENMASK_ULL(63, 48)
> +#define CXL_PMU_ATTR_CONFIG1_THRESHOLD_MSK     GENMASK_ULL(15, 0)
> +#define CXL_PMU_ATTR_CONFIG1_INVERT_MSK                BIT(16)
> +#define CXL_PMU_ATTR_CONFIG1_EDGE_MSK          BIT(17)
> +#define CXL_PMU_ATTR_CONFIG1_FILTER_EN_MSK     BIT(18)
> +#define CXL_PMU_ATTR_CONFIG2_HDM_MSK           GENMASK(15, 0)
> +
> +static umode_t cxl_pmu_format_is_visible(struct kobject *kobj,
> +                                        struct attribute *attr, int a)
> +{
> +       struct device *dev = kobj_to_dev(kobj);
> +       struct cxl_pmu_info *info = dev_get_drvdata(dev);
> +
> +       /*
> +        * Filter capability at the CPMU level, so hide the attributes if the particular
> +        * filter is not supported.
> +        */
> +       if (!info->filter_hdm &&
> +           (attr == cxl_pmu_format_attr[cxl_pmu_hdm_filter_en_attr] ||
> +            attr == cxl_pmu_format_attr[cxl_pmu_hdm_attr]))
> +               return 0;
> +
> +       return attr->mode;
> +}
> +
> +static const struct attribute_group cxl_pmu_format_group = {
> +       .name = "format",
> +       .attrs = cxl_pmu_format_attr,
> +       .is_visible = cxl_pmu_format_is_visible,
> +};
> +
> +static u32 cxl_pmu_config_get_mask(struct perf_event *event)
> +{
> +       return FIELD_GET(CXL_PMU_ATTR_CONFIG_MASK_MSK, event->attr.config);
> +}
> +
> +static u16 cxl_pmu_config_get_gid(struct perf_event *event)
> +{
> +       return FIELD_GET(CXL_PMU_ATTR_CONFIG_GID_MSK, event->attr.config);
> +}
> +
> +static u16 cxl_pmu_config_get_vid(struct perf_event *event)
> +{
> +       return FIELD_GET(CXL_PMU_ATTR_CONFIG_VID_MSK, event->attr.config);
> +}
> +
> +static u8 cxl_pmu_config1_get_threshold(struct perf_event *event)
> +{
> +       return FIELD_GET(CXL_PMU_ATTR_CONFIG1_THRESHOLD_MSK, event->attr.config1);
> +}
> +
> +static bool cxl_pmu_config1_get_invert(struct perf_event *event)
> +{
> +       return FIELD_GET(CXL_PMU_ATTR_CONFIG1_INVERT_MSK, event->attr.config1);
> +}
> +
> +static bool cxl_pmu_config1_get_edge(struct perf_event *event)
> +{
> +       return FIELD_GET(CXL_PMU_ATTR_CONFIG1_EDGE_MSK, event->attr.config1);
> +}
> +
> +/*
> + * CPMU specification allows for 8 filters, each with a 16 bit value...
> + * So we need to find 8x16bits to store it in.
> + * As the value used for disable is 0xffff, a separate enable switch
> + * is needed.
> + */
> +
> +static bool cxl_pmu_config1_hdm_filter_en(struct perf_event *event)
> +{
> +       return FIELD_GET(CXL_PMU_ATTR_CONFIG1_FILTER_EN_MSK, event->attr.config1);
> +}
> +
> +static u16 cxl_pmu_config2_get_hdm_decoder(struct perf_event *event)
> +{
> +       return FIELD_GET(CXL_PMU_ATTR_CONFIG2_HDM_MSK, event->attr.config2);
> +}
> +
> +static ssize_t cxl_pmu_event_sysfs_show(struct device *dev,
> +                                       struct device_attribute *attr, char *buf)
> +{
> +       struct perf_pmu_events_attr *pmu_attr =
> +               container_of(attr, struct perf_pmu_events_attr, attr);
> +
> +       return sysfs_emit(buf, "config=%#llx\n", pmu_attr->id);
> +}
> +
> +#define CXL_PMU_EVENT_ATTR(_name, _vid, _gid, _msk)                    \
> +       PMU_EVENT_ATTR_ID(_name, cxl_pmu_event_sysfs_show,              \
> +                         ((u64)(_vid) << 48) | ((u64)(_gid) << 32) | (u64)(_msk))
> +
> +/* For CXL spec defined events */
> +#define CXL_PMU_EVENT_CXL_ATTR(_name, _gid, _msk)                      \
> +       CXL_PMU_EVENT_ATTR(_name, PCI_DVSEC_VENDOR_ID_CXL, _gid, _msk)
> +
> +static struct attribute *cxl_pmu_event_attrs[] = {
> +       CXL_PMU_EVENT_CXL_ATTR(clock_ticks,                     CXL_PMU_GID_CLOCK_TICKS, BIT(0)),
> +       /* CXL rev 3.0 Table 3-17 - Device to Host Requests */
> +       CXL_PMU_EVENT_CXL_ATTR(d2h_req_rdcurr,                  CXL_PMU_GID_D2H_REQ, BIT(1)),
> +       CXL_PMU_EVENT_CXL_ATTR(d2h_req_rdown,                   CXL_PMU_GID_D2H_REQ, BIT(2)),
> +       CXL_PMU_EVENT_CXL_ATTR(d2h_req_rdshared,                CXL_PMU_GID_D2H_REQ, BIT(3)),
> +       CXL_PMU_EVENT_CXL_ATTR(d2h_req_rdany,                   CXL_PMU_GID_D2H_REQ, BIT(4)),
> +       CXL_PMU_EVENT_CXL_ATTR(d2h_req_rdownnodata,             CXL_PMU_GID_D2H_REQ, BIT(5)),
> +       CXL_PMU_EVENT_CXL_ATTR(d2h_req_itomwr,                  CXL_PMU_GID_D2H_REQ, BIT(6)),
> +       CXL_PMU_EVENT_CXL_ATTR(d2h_req_wrcurr,                  CXL_PMU_GID_D2H_REQ, BIT(7)),
> +       CXL_PMU_EVENT_CXL_ATTR(d2h_req_clflush,                 CXL_PMU_GID_D2H_REQ, BIT(8)),
> +       CXL_PMU_EVENT_CXL_ATTR(d2h_req_cleanevict,              CXL_PMU_GID_D2H_REQ, BIT(9)),
> +       CXL_PMU_EVENT_CXL_ATTR(d2h_req_dirtyevict,              CXL_PMU_GID_D2H_REQ, BIT(10)),
> +       CXL_PMU_EVENT_CXL_ATTR(d2h_req_cleanevictnodata,        CXL_PMU_GID_D2H_REQ, BIT(11)),
> +       CXL_PMU_EVENT_CXL_ATTR(d2h_req_wowrinv,                 CXL_PMU_GID_D2H_REQ, BIT(12)),
> +       CXL_PMU_EVENT_CXL_ATTR(d2h_req_wowrinvf,                CXL_PMU_GID_D2H_REQ, BIT(13)),
> +       CXL_PMU_EVENT_CXL_ATTR(d2h_req_wrinv,                   CXL_PMU_GID_D2H_REQ, BIT(14)),
> +       CXL_PMU_EVENT_CXL_ATTR(d2h_req_cacheflushed,            CXL_PMU_GID_D2H_REQ, BIT(16)),
> +       /* CXL rev 3.0 Table 3-20 - D2H Repsonse Encodings */
> +       CXL_PMU_EVENT_CXL_ATTR(d2h_rsp_rspihiti,                CXL_PMU_GID_D2H_RSP, BIT(4)),
> +       CXL_PMU_EVENT_CXL_ATTR(d2h_rsp_rspvhitv,                CXL_PMU_GID_D2H_RSP, BIT(6)),
> +       CXL_PMU_EVENT_CXL_ATTR(d2h_rsp_rspihitse,               CXL_PMU_GID_D2H_RSP, BIT(5)),
> +       CXL_PMU_EVENT_CXL_ATTR(d2h_rsp_rspshitse,               CXL_PMU_GID_D2H_RSP, BIT(1)),
> +       CXL_PMU_EVENT_CXL_ATTR(d2h_rsp_rspsfwdm,                CXL_PMU_GID_D2H_RSP, BIT(7)),
> +       CXL_PMU_EVENT_CXL_ATTR(d2h_rsp_rspifwdm,                CXL_PMU_GID_D2H_RSP, BIT(15)),
> +       CXL_PMU_EVENT_CXL_ATTR(d2h_rsp_rspvfwdv,                CXL_PMU_GID_D2H_RSP, BIT(22)),
> +       /* CXL rev 3.0 Table 3-21 - CXL.cache - Mapping of H2D Requests to D2H Responses */
> +       CXL_PMU_EVENT_CXL_ATTR(h2d_req_snpdata,                 CXL_PMU_GID_H2D_REQ, BIT(1)),
> +       CXL_PMU_EVENT_CXL_ATTR(h2d_req_snpinv,                  CXL_PMU_GID_H2D_REQ, BIT(2)),
> +       CXL_PMU_EVENT_CXL_ATTR(h2d_req_snpcur,                  CXL_PMU_GID_H2D_REQ, BIT(3)),
> +       /* CXL rev 3.0 Table 3-22 - H2D Response Opcode Encodings */
> +       CXL_PMU_EVENT_CXL_ATTR(h2d_rsp_writepull,               CXL_PMU_GID_H2D_RSP, BIT(1)),
> +       CXL_PMU_EVENT_CXL_ATTR(h2d_rsp_go,                      CXL_PMU_GID_H2D_RSP, BIT(4)),
> +       CXL_PMU_EVENT_CXL_ATTR(h2d_rsp_gowritepull,             CXL_PMU_GID_H2D_RSP, BIT(5)),
> +       CXL_PMU_EVENT_CXL_ATTR(h2d_rsp_extcmp,                  CXL_PMU_GID_H2D_RSP, BIT(6)),
> +       CXL_PMU_EVENT_CXL_ATTR(h2d_rsp_gowritepulldrop,         CXL_PMU_GID_H2D_RSP, BIT(8)),
> +       CXL_PMU_EVENT_CXL_ATTR(h2d_rsp_fastgowritepull,         CXL_PMU_GID_H2D_RSP, BIT(13)),
> +       CXL_PMU_EVENT_CXL_ATTR(h2d_rsp_goerrwritepull,          CXL_PMU_GID_H2D_RSP, BIT(15)),
> +       /* CXL rev 3.0 Table 13-5 directly lists these */
> +       CXL_PMU_EVENT_CXL_ATTR(cachedata_d2h_data,              CXL_PMU_GID_CACHE_DATA, BIT(0)),
> +       CXL_PMU_EVENT_CXL_ATTR(cachedata_h2d_data,              CXL_PMU_GID_CACHE_DATA, BIT(1)),
> +       /* CXL rev 3.0 Table 3-29 M2S Req Memory Opcodes */
> +       CXL_PMU_EVENT_CXL_ATTR(m2s_req_meminv,                  CXL_PMU_GID_M2S_REQ, BIT(0)),
> +       CXL_PMU_EVENT_CXL_ATTR(m2s_req_memrd,                   CXL_PMU_GID_M2S_REQ, BIT(1)),
> +       CXL_PMU_EVENT_CXL_ATTR(m2s_req_memrddata,               CXL_PMU_GID_M2S_REQ, BIT(2)),
> +       CXL_PMU_EVENT_CXL_ATTR(m2s_req_memrdfwd,                CXL_PMU_GID_M2S_REQ, BIT(3)),
> +       CXL_PMU_EVENT_CXL_ATTR(m2s_req_memwrfwd,                CXL_PMU_GID_M2S_REQ, BIT(4)),
> +       CXL_PMU_EVENT_CXL_ATTR(m2s_req_memspecrd,               CXL_PMU_GID_M2S_REQ, BIT(8)),
> +       CXL_PMU_EVENT_CXL_ATTR(m2s_req_meminvnt,                CXL_PMU_GID_M2S_REQ, BIT(9)),
> +       CXL_PMU_EVENT_CXL_ATTR(m2s_req_memcleanevict,           CXL_PMU_GID_M2S_REQ, BIT(10)),
> +       /* CXL rev 3.0 Table 3-35 M2S RwD Memory Opcodes */
> +       CXL_PMU_EVENT_CXL_ATTR(m2s_rwd_memwr,                   CXL_PMU_GID_M2S_RWD, BIT(1)),
> +       CXL_PMU_EVENT_CXL_ATTR(m2s_rwd_memwrptl,                CXL_PMU_GID_M2S_RWD, BIT(2)),
> +       CXL_PMU_EVENT_CXL_ATTR(m2s_rwd_biconflict,              CXL_PMU_GID_M2S_RWD, BIT(4)),
> +       /* CXL rev 3.0 Table 3-38 M2S BIRsp Memory Opcodes */
> +       CXL_PMU_EVENT_CXL_ATTR(m2s_birsp_i,                     CXL_PMU_GID_M2S_BIRSP, BIT(0)),
> +       CXL_PMU_EVENT_CXL_ATTR(m2s_birsp_s,                     CXL_PMU_GID_M2S_BIRSP, BIT(1)),
> +       CXL_PMU_EVENT_CXL_ATTR(m2s_birsp_e,                     CXL_PMU_GID_M2S_BIRSP, BIT(2)),
> +       CXL_PMU_EVENT_CXL_ATTR(m2s_birsp_iblk,                  CXL_PMU_GID_M2S_BIRSP, BIT(4)),
> +       CXL_PMU_EVENT_CXL_ATTR(m2s_birsp_sblk,                  CXL_PMU_GID_M2S_BIRSP, BIT(5)),
> +       CXL_PMU_EVENT_CXL_ATTR(m2s_birsp_eblk,                  CXL_PMU_GID_M2S_BIRSP, BIT(6)),
> +       /* CXL rev 3.0 Table 3-40 S2M BISnp Opcodes */
> +       CXL_PMU_EVENT_CXL_ATTR(s2m_bisnp_cur,                   CXL_PMU_GID_S2M_BISNP, BIT(0)),
> +       CXL_PMU_EVENT_CXL_ATTR(s2m_bisnp_data,                  CXL_PMU_GID_S2M_BISNP, BIT(1)),
> +       CXL_PMU_EVENT_CXL_ATTR(s2m_bisnp_inv,                   CXL_PMU_GID_S2M_BISNP, BIT(2)),
> +       CXL_PMU_EVENT_CXL_ATTR(s2m_bisnp_curblk,                CXL_PMU_GID_S2M_BISNP, BIT(4)),
> +       CXL_PMU_EVENT_CXL_ATTR(s2m_bisnp_datblk,                CXL_PMU_GID_S2M_BISNP, BIT(5)),
> +       CXL_PMU_EVENT_CXL_ATTR(s2m_bisnp_invblk,                CXL_PMU_GID_S2M_BISNP, BIT(6)),
> +       /* CXL rev 3.0 Table 3-43 S2M NDR Opcopdes */
> +       CXL_PMU_EVENT_CXL_ATTR(s2m_ndr_cmp,                     CXL_PMU_GID_S2M_NDR, BIT(0)),
> +       CXL_PMU_EVENT_CXL_ATTR(s2m_ndr_cmps,                    CXL_PMU_GID_S2M_NDR, BIT(1)),
> +       CXL_PMU_EVENT_CXL_ATTR(s2m_ndr_cmpe,                    CXL_PMU_GID_S2M_NDR, BIT(2)),
> +       CXL_PMU_EVENT_CXL_ATTR(s2m_ndr_biconflictack,           CXL_PMU_GID_S2M_NDR, BIT(3)),
> +       /* CXL rev 3.0 Table 3-46 S2M DRS opcodes */
> +       CXL_PMU_EVENT_CXL_ATTR(s2m_drs_memdata,                 CXL_PMU_GID_S2M_DRS, BIT(0)),
> +       CXL_PMU_EVENT_CXL_ATTR(s2m_drs_memdatanxm,              CXL_PMU_GID_S2M_DRS, BIT(1)),
> +       /* CXL rev 3.0 Table 13-5 directly lists these */
> +       CXL_PMU_EVENT_CXL_ATTR(ddr_act,                         CXL_PMU_GID_DDR, BIT(0)),
> +       CXL_PMU_EVENT_CXL_ATTR(ddr_pre,                         CXL_PMU_GID_DDR, BIT(1)),
> +       CXL_PMU_EVENT_CXL_ATTR(ddr_casrd,                       CXL_PMU_GID_DDR, BIT(2)),
> +       CXL_PMU_EVENT_CXL_ATTR(ddr_caswr,                       CXL_PMU_GID_DDR, BIT(3)),
> +       CXL_PMU_EVENT_CXL_ATTR(ddr_refresh,                     CXL_PMU_GID_DDR, BIT(4)),
> +       CXL_PMU_EVENT_CXL_ATTR(ddr_selfrefreshent,              CXL_PMU_GID_DDR, BIT(5)),
> +       CXL_PMU_EVENT_CXL_ATTR(ddr_rfm,                         CXL_PMU_GID_DDR, BIT(6)),
> +       NULL
> +};
> +
> +static struct cxl_pmu_ev_cap *cxl_pmu_find_fixed_counter_ev_cap(struct cxl_pmu_info *info,
> +                                                               int vid, int gid, int msk)
> +{
> +       struct cxl_pmu_ev_cap *pmu_ev;
> +
> +       list_for_each_entry(pmu_ev, &info->event_caps_fixed, node) {
> +               if (vid != pmu_ev->vid || gid != pmu_ev->gid)
> +                       continue;
> +
> +               /* Precise match for fixed counter */
> +               if (msk == pmu_ev->msk)
> +                       return pmu_ev;
> +       }
> +
> +       return ERR_PTR(-EINVAL);
> +}
> +
> +static struct cxl_pmu_ev_cap *cxl_pmu_find_config_counter_ev_cap(struct cxl_pmu_info *info,
> +                                                                int vid, int gid, int msk)
> +{
> +       struct cxl_pmu_ev_cap *pmu_ev;
> +
> +       list_for_each_entry(pmu_ev, &info->event_caps_configurable, node) {
> +               if (vid != pmu_ev->vid || gid != pmu_ev->gid)
> +                       continue;
> +
> +               /* Request mask must be subset of supported */
> +               if (msk & ~pmu_ev->msk)
> +                       continue;
> +
> +               return pmu_ev;
> +       }
> +
> +       return ERR_PTR(-EINVAL);
> +}
> +
> +static umode_t cxl_pmu_event_is_visible(struct kobject *kobj, struct attribute *attr, int a)
> +{
> +       struct device_attribute *dev_attr = container_of(attr, struct device_attribute, attr);
> +       struct perf_pmu_events_attr *pmu_attr =
> +               container_of(dev_attr, struct perf_pmu_events_attr, attr);
> +       struct device *dev = kobj_to_dev(kobj);
> +       struct cxl_pmu_info *info = dev_get_drvdata(dev);
> +       int vid = FIELD_GET(CXL_PMU_ATTR_CONFIG_VID_MSK, pmu_attr->id);
> +       int gid = FIELD_GET(CXL_PMU_ATTR_CONFIG_GID_MSK, pmu_attr->id);
> +       int msk = FIELD_GET(CXL_PMU_ATTR_CONFIG_MASK_MSK, pmu_attr->id);
> +
> +       if (!IS_ERR(cxl_pmu_find_fixed_counter_ev_cap(info, vid, gid, msk)))
> +               return attr->mode;
> +
> +       if (!IS_ERR(cxl_pmu_find_config_counter_ev_cap(info, vid, gid, msk)))
> +               return attr->mode;
> +
> +       return 0;
> +}
> +
> +static const struct attribute_group cxl_pmu_events = {
> +       .name = "events",
> +       .attrs = cxl_pmu_event_attrs,
> +       .is_visible = cxl_pmu_event_is_visible,
> +};
> +
> +static ssize_t cpumask_show(struct device *dev, struct device_attribute *attr,
> +                           char *buf)
> +{
> +       struct cxl_pmu_info *info = dev_get_drvdata(dev);
> +
> +       return cpumap_print_to_pagebuf(true, buf, cpumask_of(info->on_cpu));
> +}
> +static DEVICE_ATTR_RO(cpumask);
> +
> +static struct attribute *cxl_pmu_cpumask_attrs[] = {
> +       &dev_attr_cpumask.attr,
> +       NULL
> +};
> +
> +static const struct attribute_group cxl_pmu_cpumask_group = {
> +       .attrs = cxl_pmu_cpumask_attrs,
> +};
> +
> +static const struct attribute_group *cxl_pmu_attr_groups[] = {
> +       &cxl_pmu_events,
> +       &cxl_pmu_format_group,
> +       &cxl_pmu_cpumask_group,
> +       NULL
> +};
> +
> +/* If counter_idx == NULL, don't try to allocate a counter. */
> +static int cxl_pmu_get_event_idx(struct perf_event *event, int *counter_idx,
> +                                int *event_idx)
> +{
> +       struct cxl_pmu_info *info = pmu_to_cxl_pmu_info(event->pmu);
> +       DECLARE_BITMAP(configurable_and_free, CXL_PMU_MAX_COUNTERS);
> +       struct cxl_pmu_ev_cap *pmu_ev;
> +       u32 mask;
> +       u16 gid, vid;
> +       int i;
> +
> +       vid = cxl_pmu_config_get_vid(event);
> +       gid = cxl_pmu_config_get_gid(event);
> +       mask = cxl_pmu_config_get_mask(event);
> +
> +       pmu_ev = cxl_pmu_find_fixed_counter_ev_cap(info, vid, gid, mask);
> +       if (!IS_ERR(pmu_ev)) {
> +               if (!counter_idx)
> +                       return 0;
> +               if (!test_bit(pmu_ev->counter_idx, info->used_counter_bm)) {
> +                       *counter_idx = pmu_ev->counter_idx;
> +                       return 0;
> +               }
> +               /* Fixed counter is in use, but maybe a configurable one? */
> +       }
> +
> +       pmu_ev = cxl_pmu_find_config_counter_ev_cap(info, vid, gid, mask);
> +       if (!IS_ERR(pmu_ev)) {
> +               if (!counter_idx)
> +                       return 0;
> +
> +               bitmap_andnot(configurable_and_free, info->conf_counter_bm,
> +                       info->used_counter_bm, CXL_PMU_MAX_COUNTERS);
> +
> +               i = find_first_bit(configurable_and_free, CXL_PMU_MAX_COUNTERS);
> +               if (i == CXL_PMU_MAX_COUNTERS)
> +                       return -EINVAL;
> +
> +               *counter_idx = i;
> +               return 0;
> +       }
> +
> +       return -EINVAL;
> +}
> +
> +static int cxl_pmu_event_init(struct perf_event *event)
> +{
> +       struct cxl_pmu_info *info = pmu_to_cxl_pmu_info(event->pmu);
> +       int rc;
> +
> +       /* Top level type sanity check - is this a Hardware Event being requested */
> +       if (event->attr.type != event->pmu->type)
> +               return -ENOENT;
> +
> +       if (is_sampling_event(event) || event->attach_state & PERF_ATTACH_TASK)
> +               return -EOPNOTSUPP;
> +       /* TODO: Validation of any filter */
> +
> +       /*
> +        * Verify that it is possible to count what was requested. Either must
> +        * be a fixed counter that is a precise match or a configurable counter
> +        * where this is a subset.
> +        */
> +       rc = cxl_pmu_get_event_idx(event, NULL, NULL);
> +       if (rc < 0)
> +               return rc;
> +
> +       event->cpu = info->on_cpu;
> +
> +       return 0;
> +}
> +
> +static void cxl_pmu_enable(struct pmu *pmu)
> +{
> +       struct cxl_pmu_info *info = pmu_to_cxl_pmu_info(pmu);
> +       void __iomem *base = info->base;
> +
> +       /* Can assume frozen at this stage */
> +       writeq(0, base + CXL_PMU_FREEZE_REG);
> +}
> +
> +static void cxl_pmu_disable(struct pmu *pmu)
> +{
> +       struct cxl_pmu_info *info = pmu_to_cxl_pmu_info(pmu);
> +       void __iomem *base = info->base;
> +
> +       /*
> +        * Whilst bits above number of counters are RsvdZ
> +        * they are unlikely to be repurposed given
> +        * number of counters is allowed to be 64 leaving
> +        * no reserved bits.  Hence this is only slightly
> +        * naughty.
> +        */
> +       writeq(GENMASK_ULL(63, 0), base + CXL_PMU_FREEZE_REG);
> +}
> +
> +static void cxl_pmu_event_start(struct perf_event *event, int flags)
> +{
> +       struct cxl_pmu_info *info = pmu_to_cxl_pmu_info(event->pmu);
> +       struct hw_perf_event *hwc = &event->hw;
> +       void __iomem *base = info->base;
> +       u64 cfg;
> +
> +       /*
> +        * All paths to here should either set these flags directly or
> +        * call cxl_pmu_event_stop() which will ensure the correct state.
> +        */
> +       if (WARN_ON_ONCE(!(hwc->state & PERF_HES_STOPPED)))
> +               return;
> +
> +       WARN_ON_ONCE(!(hwc->state & PERF_HES_UPTODATE));
> +       hwc->state = 0;
> +
> +       /*
> +        * Currently only hdm filter control is implemented, this code will
> +        * want generalizing when more filters are added.
> +        */
> +       if (info->filter_hdm) {
> +               if (cxl_pmu_config1_hdm_filter_en(event))
> +                       cfg = cxl_pmu_config2_get_hdm_decoder(event);
> +               else
> +                       cfg = GENMASK(15, 0); /* No filtering if 0xFFFF_FFFF */
> +               writeq(cfg, base + CXL_PMU_FILTER_CFG_REG(hwc->idx, 0));
> +       }
> +
> +       cfg = readq(base + CXL_PMU_COUNTER_CFG_REG(hwc->idx));
> +       cfg |= FIELD_PREP(CXL_PMU_COUNTER_CFG_INT_ON_OVRFLW, 1);
> +       cfg |= FIELD_PREP(CXL_PMU_COUNTER_CFG_FREEZE_ON_OVRFLW, 1);
> +       cfg |= FIELD_PREP(CXL_PMU_COUNTER_CFG_ENABLE, 1);
> +       cfg |= FIELD_PREP(CXL_PMU_COUNTER_CFG_EDGE,
> +                         cxl_pmu_config1_get_edge(event) ? 1 : 0);
> +       cfg |= FIELD_PREP(CXL_PMU_COUNTER_CFG_INVERT,
> +                         cxl_pmu_config1_get_invert(event) ? 1 : 0);
> +
> +       /* Fixed purpose counters have next two fields RO */
> +       if (test_bit(hwc->idx, info->conf_counter_bm)) {
> +               cfg |= FIELD_PREP(CXL_PMU_COUNTER_CFG_EVENT_GRP_ID_IDX_MSK,
> +                                 hwc->event_base);
> +               cfg |= FIELD_PREP(CXL_PMU_COUNTER_CFG_EVENTS_MSK,
> +                                 cxl_pmu_config_get_mask(event));
> +       }
> +       cfg &= ~CXL_PMU_COUNTER_CFG_THRESHOLD_MSK;
> +       /*
> +        * For events that generate only 1 count per clock the CXL 3.0 spec
> +        * states the threshold shall be set to 1 but if set to 0 it will
> +        * count the raw value anyway?
> +        * There is no definition of what events will count multiple per cycle
> +        * and hence to which non 1 values of threshold can apply.
> +        * (CXL 3.0 8.2.7.2.1 Counter Configuration - threshold field definition)
> +        */
> +       cfg |= FIELD_PREP(CXL_PMU_COUNTER_CFG_THRESHOLD_MSK,
> +                         cxl_pmu_config1_get_threshold(event));
> +       writeq(cfg, base + CXL_PMU_COUNTER_CFG_REG(hwc->idx));
> +
> +       local64_set(&hwc->prev_count, 0);
> +       writeq(0, base + CXL_PMU_COUNTER_REG(hwc->idx));
> +
> +       perf_event_update_userpage(event);
> +}
> +
> +static u64 cxl_pmu_read_counter(struct perf_event *event)
> +{
> +       struct cxl_pmu_info *info = pmu_to_cxl_pmu_info(event->pmu);
> +       void __iomem *base = info->base;
> +
> +       return readq(base + CXL_PMU_COUNTER_REG(event->hw.idx));
> +}
> +
> +static void __cxl_pmu_read(struct perf_event *event, bool overflow)
> +{
> +       struct cxl_pmu_info *info = pmu_to_cxl_pmu_info(event->pmu);
> +       struct hw_perf_event *hwc = &event->hw;
> +       u64 new_cnt, prev_cnt, delta;
> +
> +       do {
> +               prev_cnt = local64_read(&hwc->prev_count);
> +               new_cnt = cxl_pmu_read_counter(event);
> +       } while (local64_cmpxchg(&hwc->prev_count, prev_cnt, new_cnt) != prev_cnt);
> +
> +       /*
> +        * If we know an overflow occur then take that into account.
> +        * Note counter is not reset as that would lose events
> +        */
> +       delta = (new_cnt - prev_cnt) & GENMASK_ULL(info->counter_width - 1, 0);
> +       if (overflow && delta < GENMASK_ULL(info->counter_width - 1, 0))
> +               delta += (1UL << info->counter_width);
> +
> +       local64_add(delta, &event->count);
> +}
> +
> +static void cxl_pmu_read(struct perf_event *event)
> +{
> +       __cxl_pmu_read(event, false);
> +}
> +
> +static void cxl_pmu_event_stop(struct perf_event *event, int flags)
> +{
> +       struct cxl_pmu_info *info = pmu_to_cxl_pmu_info(event->pmu);
> +       void __iomem *base = info->base;
> +       struct hw_perf_event *hwc = &event->hw;
> +       u64 cfg;
> +
> +       cxl_pmu_read(event);
> +       WARN_ON_ONCE(hwc->state & PERF_HES_STOPPED);
> +       hwc->state |= PERF_HES_STOPPED;
> +
> +       cfg = readq(base + CXL_PMU_COUNTER_CFG_REG(hwc->idx));
> +       cfg &= ~(FIELD_PREP(CXL_PMU_COUNTER_CFG_INT_ON_OVRFLW, 1) |
> +                FIELD_PREP(CXL_PMU_COUNTER_CFG_ENABLE, 1));
> +       writeq(cfg, base + CXL_PMU_COUNTER_CFG_REG(hwc->idx));
> +
> +       hwc->state |= PERF_HES_UPTODATE;
> +}
> +
> +static int cxl_pmu_event_add(struct perf_event *event, int flags)
> +{
> +       struct cxl_pmu_info *info = pmu_to_cxl_pmu_info(event->pmu);
> +       struct hw_perf_event *hwc = &event->hw;
> +       int idx, rc;
> +       int event_idx = 0;
> +
> +       hwc->state = PERF_HES_STOPPED | PERF_HES_UPTODATE;
> +
> +       rc = cxl_pmu_get_event_idx(event, &idx, &event_idx);
> +       if (rc < 0)
> +               return rc;
> +
> +       hwc->idx = idx;
> +
> +       /* Only set for configurable counters */
> +       hwc->event_base = event_idx;
> +       info->hw_events[idx] = event;
> +       set_bit(idx, info->used_counter_bm);
> +
> +       if (flags & PERF_EF_START)
> +               cxl_pmu_event_start(event, PERF_EF_RELOAD);
> +
> +       return 0;
> +}
> +
> +static void cxl_pmu_event_del(struct perf_event *event, int flags)
> +{
> +       struct cxl_pmu_info *info = pmu_to_cxl_pmu_info(event->pmu);
> +       struct hw_perf_event *hwc = &event->hw;
> +
> +       cxl_pmu_event_stop(event, PERF_EF_UPDATE);
> +       clear_bit(hwc->idx, info->used_counter_bm);
> +       info->hw_events[hwc->idx] = NULL;
> +       perf_event_update_userpage(event);
> +}
> +
> +static irqreturn_t cxl_pmu_irq(int irq, void *data)
> +{
> +       struct cxl_pmu_info *info = data;
> +       void __iomem *base = info->base;
> +       u64 overflowed;
> +       DECLARE_BITMAP(overflowedbm, 64);
> +       int i;
> +
> +       overflowed = readq(base + CXL_PMU_OVERFLOW_REG);
> +
> +       /* Interrupt may be shared, so maybe it isn't ours */
> +       if (!overflowed)
> +               return IRQ_NONE;
> +
> +       bitmap_from_arr64(overflowedbm, &overflowed, 64);
> +       for_each_set_bit(i, overflowedbm, info->num_counters) {
> +               struct perf_event *event = info->hw_events[i];
> +
> +               if (!event) {
> +                       dev_dbg(info->pmu.dev,
> +                               "overflow but on non enabled counter %d\n", i);
> +                       continue;
> +               }
> +
> +               __cxl_pmu_read(event, true);
> +       }
> +
> +       writeq(overflowed, base + CXL_PMU_OVERFLOW_REG);
> +
> +       return IRQ_HANDLED;
> +}
> +
> +static void cxl_pmu_perf_unregister(void *_info)
> +{
> +       struct cxl_pmu_info *info = _info;
> +
> +       perf_pmu_unregister(&info->pmu);
> +}
> +
> +static void cxl_pmu_cpuhp_remove(void *_info)
> +{
> +       struct cxl_pmu_info *info = _info;
> +
> +       cpuhp_state_remove_instance_nocalls(cxl_pmu_cpuhp_state_num, &info->node);
> +}
> +
> +static int cxl_pmu_probe(struct device *dev)
> +{
> +       struct cxl_pmu *pmu = to_cxl_pmu(dev);
> +       struct pci_dev *pdev = to_pci_dev(dev->parent);
> +       struct cxl_pmu_info *info;
> +       char *irq_name;
> +       char *dev_name;
> +       int rc, irq;
> +
> +       info = devm_kzalloc(dev, sizeof(*info), GFP_KERNEL);
> +       if (!info)
> +               return -ENOMEM;
> +
> +       dev_set_drvdata(dev, info);
> +       INIT_LIST_HEAD(&info->event_caps_fixed);
> +       INIT_LIST_HEAD(&info->event_caps_configurable);
> +
> +       info->base = pmu->base;
> +
> +       info->on_cpu = -1;
> +       rc = cxl_pmu_parse_caps(dev, info);
> +       if (rc)
> +               return rc;
> +
> +       info->hw_events = devm_kcalloc(dev, sizeof(*info->hw_events),
> +                                      info->num_counters, GFP_KERNEL);
> +       if (!info->hw_events)
> +               return -ENOMEM;
> +
> +       switch (pmu->type) {
> +       case CXL_PMU_MEMDEV:
> +               dev_name = devm_kasprintf(dev, GFP_KERNEL, "cxl_pmu_mem%d.%d",
> +                                         pmu->assoc_id, pmu->index);
> +               break;
> +       }
> +       if (!dev_name)
> +               return -ENOMEM;
> +
> +       info->pmu = (struct pmu) {
> +               .name = dev_name,
> +               .parent = dev,
> +               .module = THIS_MODULE,
> +               .event_init = cxl_pmu_event_init,
> +               .pmu_enable = cxl_pmu_enable,
> +               .pmu_disable = cxl_pmu_disable,
> +               .add = cxl_pmu_event_add,
> +               .del = cxl_pmu_event_del,
> +               .start = cxl_pmu_event_start,
> +               .stop = cxl_pmu_event_stop,
> +               .read = cxl_pmu_read,
> +               .task_ctx_nr = perf_invalid_context,
> +               .attr_groups = cxl_pmu_attr_groups,
> +               .capabilities = PERF_PMU_CAP_NO_EXCLUDE,
> +       };
> +
> +       if (info->irq <= 0)
> +               return -EINVAL;
> +
> +       rc = pci_irq_vector(pdev, info->irq);
> +       if (rc < 0)
> +               return rc;
> +       irq = rc;
> +
> +       irq_name = devm_kasprintf(dev, GFP_KERNEL, "%s_overflow\n", dev_name);
> +       if (!irq_name)
> +               return -ENOMEM;
> +
> +       rc = devm_request_irq(dev, irq, cxl_pmu_irq, IRQF_SHARED | IRQF_ONESHOT,
> +                             irq_name, info);
> +       if (rc)
> +               return rc;
> +       info->irq = irq;
> +
> +       rc = cpuhp_state_add_instance(cxl_pmu_cpuhp_state_num, &info->node);
> +       if (rc)
> +               return rc;
> +
> +       rc = devm_add_action_or_reset(dev, cxl_pmu_cpuhp_remove, info);
> +       if (rc)
> +               return rc;
> +
> +       rc = perf_pmu_register(&info->pmu, info->pmu.name, -1);
> +       if (rc)
> +               return rc;
> +
> +       rc = devm_add_action_or_reset(dev, cxl_pmu_perf_unregister, info);
> +       if (rc)
> +               return rc;
> +
> +       return 0;
> +}
> +
> +static struct cxl_driver cxl_pmu_driver = {
> +       .name = "cxl_pmu",
> +       .probe = cxl_pmu_probe,
> +       .id = CXL_DEVICE_PMU,
> +};
> +
> +static int cxl_pmu_online_cpu(unsigned int cpu, struct hlist_node *node)
> +{
> +       struct cxl_pmu_info *info = hlist_entry_safe(node, struct cxl_pmu_info, node);
> +
> +       if (info->on_cpu != -1)
> +               return 0;
> +
> +       info->on_cpu = cpu;
> +       /*
> +        * CPU HP lock is held so we should be guaranteed that the CPU hasn't yet
> +        * gone away again.
> +        */
> +       WARN_ON(irq_set_affinity(info->irq, cpumask_of(cpu)));
> +
> +       return 0;
> +}
> +
> +static int cxl_pmu_offline_cpu(unsigned int cpu, struct hlist_node *node)
> +{
> +       struct cxl_pmu_info *info = hlist_entry_safe(node, struct cxl_pmu_info, node);
> +       unsigned int target;
> +
> +       if (info->on_cpu != cpu)
> +               return 0;
> +
> +       info->on_cpu = -1;
> +       target = cpumask_any_but(cpu_online_mask, cpu);
> +       if (target >= nr_cpu_ids) {
> +               dev_err(info->pmu.dev, "Unable to find a suitable CPU\n");
> +               return 0;
> +       }
> +
> +       perf_pmu_migrate_context(&info->pmu, cpu, target);
> +       info->on_cpu = target;
> +       /*
> +        * CPU HP lock is held so we should be guaranteed that this CPU hasn't yet
> +        * gone away.
> +        */
> +       WARN_ON(irq_set_affinity(info->irq, cpumask_of(target)));
> +
> +       return 0;
> +}
> +
> +static __init int cxl_pmu_init(void)
> +{
> +       int rc;
> +
> +       rc = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN,
> +                                    "AP_PERF_CXL_PMU_ONLINE",
> +                                    cxl_pmu_online_cpu, cxl_pmu_offline_cpu);
> +       if (rc < 0)
> +               return rc;
> +       cxl_pmu_cpuhp_state_num = rc;
> +
> +       rc = cxl_driver_register(&cxl_pmu_driver);
> +       if (rc)
> +               cpuhp_remove_multi_state(cxl_pmu_cpuhp_state_num);
> +
> +       return rc;
> +}
> +
> +static __exit void cxl_pmu_exit(void)
> +{
> +       cxl_driver_unregister(&cxl_pmu_driver);
> +       cpuhp_remove_multi_state(cxl_pmu_cpuhp_state_num);
> +}
> +
> +MODULE_LICENSE("GPL");
> +MODULE_IMPORT_NS(CXL);
> +module_init(cxl_pmu_init);
> +module_exit(cxl_pmu_exit);
> +MODULE_ALIAS_CXL(CXL_DEVICE_PMU);
> --
> 2.39.2
>