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Message-ID: <593eb71a-e4a5-a6cc-07a2-efe7230c3555@linux.intel.com>
Date:   Wed, 12 Apr 2023 09:55:20 -0400
From:   "Liang, Kan" <kan.liang@...ux.intel.com>
To:     Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        linux-cxl@...r.kernel.org, peterz@...radead.org,
        mark.rutland@....com, will@...nel.org
Cc:     mingo@...hat.com, acme@...nel.org, dan.j.williams@...el.com,
        linuxarm@...wei.com, linux-perf-users@...r.kernel.org,
        linux-kernel@...r.kernel.org, Davidlohr Bueso <dave@...olabs.net>,
        Dave Jiang <dave.jiang@...el.com>
Subject: Re: [PATCH v5 4/5] perf: CXL Performance Monitoring Unit driver



On 2023-04-11 2:54 p.m., Jonathan Cameron 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 -e cxl_pmu_mem0.0/h2d_req_snpcur/ -e cpmu0/h2d_req_snpdata/ -e cpmu0/clock_ticks/ sleep 1
> 
> Performance counter stats for 'system wide':
> 
> 96,757,023,244,321      cpmu0/h2d_req_snpcur/
> 96,757,023,244,365      cpmu0/h2d_req_snpdata/
> 193,514,046,488,653      cpmu0/clock_ticks/
> 
>        1.090539600 seconds time elapsed

I think the example has to be updated. We don't have cpmu0 anymore, right?

Except that, the rest of the patch looks good to me.

Reviewed-by: Kan Liang <kan.liang@...ux.intel.com>

Thanks,
Kan

> 
> Reviewed-by: Dave Jiang <dave.jiang@...el.com>
> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
> 
> ---
> v5: Thanks to Kan Liang and Dan Williams for review.
> - Move driver to drivers/perf and rename patch to reflect that.
> - Add a MAINTAINERS entry now driver doesn't fall under drivers/cxl.
> - Fix mask
> - Drop duplication of counter reset and config writing (which also
>   gets rid of a write to an entirely read only register)
> - Lots of cpmu->pmu and similar renames.
> - Rename the cxl_pmu_event and related to cxl_pmu_ev_cap so as to avoid
>   impression that there is one of these for every event.  They reflect the
>   event capability registers hence the new naming.  Rename the two lists
>   to reflect this as well.
> - Comments on WARN_ON cases.
> - Fixed a bug in cpuhp offline callback where we could move to the cpu
>   that is going away.
> - Use devm_add_action_or_reset () for remaining few bits of remove()
> - Richer PMU naming as cxl_pmu_memX.Y to associate with
>   /sys/bus/cxl/device/memX instance of PMU Y.  Scheme extents for
>   USP cxl_pmu_uspX.Y and DSP cxl_pmu_dspX.Y.Z for DSP Y of USP X,
>   PMU instance Z.
> ---
>  MAINTAINERS            |   6 +
>  drivers/cxl/Kconfig    |  13 +
>  drivers/perf/Kconfig   |  13 +
>  drivers/perf/Makefile  |   1 +
>  drivers/perf/cxl_pmu.c | 984 +++++++++++++++++++++++++++++++++++++++++
>  5 files changed, 1017 insertions(+)
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 90abe83c02f3..51234eb7858e 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -5174,6 +5174,12 @@ S:	Maintained
>  F:	drivers/cxl/
>  F:	include/uapi/linux/cxl_mem.h
>  
> +COMPUTE EXPRESS LINK PMU (CPMU)
> +M:	Jonathan Cameron <jonathan.cameron@...wei.com>
> +L:	linux-cxl@...r.kernel.org
> +S:	Maintained
> +F:	drivers/perf/cxl_pmu.c
> +
>  CONEXANT ACCESSRUNNER USB DRIVER
>  L:	accessrunner-general@...ts.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 66c259000a44..ffeabb14df9e 100644
> --- a/drivers/perf/Kconfig
> +++ b/drivers/perf/Kconfig
> @@ -203,4 +203,17 @@ 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 13e45da61100..900af2c6c4f0 100644
> --- a/drivers/perf/Makefile
> +++ b/drivers/perf/Makefile
> @@ -23,3 +23,4 @@ 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..29d8b64a11b6
> --- /dev/null
> +++ b/drivers/perf/cxl_pmu.c
> @@ -0,0 +1,984 @@
> +// 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);
> +
> +	event->cpu = info->on_cpu;
> +	/* 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.
> +	 */
> +	return cxl_pmu_get_event_idx(event, NULL, NULL);
> +}
> +
> +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 implemnted, 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 anwyay?
> +	 * 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);

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