diff --git a/drivers/cxl/Kconfig b/drivers/cxl/Kconfig
index ff4e78117b31..d68fc5769c58 100644
--- a/drivers/cxl/Kconfig
+++ b/drivers/cxl/Kconfig
@@ -139,4 +139,16 @@ config CXL_REGION_INVALIDATION_TEST
 	  If unsure, or if this kernel is meant for production environments,
 	  say N.
 
+config CXL_CPMU
+	tristate "CXL Performance Monitoring Unit"
+	default 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'.
 endif
diff --git a/drivers/cxl/Makefile b/drivers/cxl/Makefile
index db321f48ba52..024bb739554b 100644
--- a/drivers/cxl/Makefile
+++ b/drivers/cxl/Makefile
@@ -5,6 +5,7 @@ obj-$(CONFIG_CXL_MEM) += cxl_mem.o
 obj-$(CONFIG_CXL_ACPI) += cxl_acpi.o
 obj-$(CONFIG_CXL_PMEM) += cxl_pmem.o
 obj-$(CONFIG_CXL_PORT) += cxl_port.o
+obj-$(CONFIG_CXL_CPMU) += cpmu.o
 
 cxl_mem-y := mem.o
 cxl_pci-y := pci.o
diff --git a/drivers/cxl/cpmu.c b/drivers/cxl/cpmu.c
new file mode 100644
index 000000000000..7a259f9de05e
--- /dev/null
+++ b/drivers/cxl/cpmu.c
@@ -0,0 +1,937 @@
+// 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
+ *
+ * TODO
+ * o Discoverability of counters. Allow perftool to provide summed counters
+ *   and vendor defined counters.
+ * o Support free running counters - copy the Intel uncore PMU handling for these.
+ * o CPMUs which do not support freeze.
+ * o Add filter validation in cpmu_event_init() so problems are detected earlier.
+ * o Reject configurations that the hardware is ignoring
+ *   (e.g. invert when not invertible)
+ * o Support CPMUs with no interrupts using an HRTIMER.
+ */
+
+#include <linux/bitops.h>
+#include <linux/bits.h>
+#include <linux/bug.h>
+#include <linux/device.h>
+#include <linux/list.h>
+#include <linux/pci.h>
+#include <linux/perf_event.h>
+#include "cpmu.h"
+#include "cxlpci.h"
+#include "cxl.h"
+
+/* CXL rev 3.0 Table 13-5 Events under CXL Vendor ID */
+#define CPMU_GID_CLOCK_TICKS		0x00
+#define CPMU_GID_D2H_REQ		0x0010
+#define CPMU_GID_D2H_RSP		0x0011
+#define CPMU_GID_H2D_REQ		0x0012
+#define CPMU_GID_H2D_RSP		0x0013
+#define CPMU_GID_CACHE_DATA		0x0014
+#define CPMU_GID_M2S_REQ		0x0020
+#define CPMU_GID_M2S_RWD		0x0021
+#define CPMU_GID_M2S_BIRSP		0x0022
+#define CPMU_GID_S2M_BISNP		0x0023
+#define CPMU_GID_S2M_NDR		0x0024
+#define CPMU_GID_S2M_DRS		0x0025
+#define CPMU_GID_DDR			0x8000
+
+static int cpmu_cpuhp_state_num;
+
+struct cpmu_event {
+	u16 vid;
+	u16 gid;
+	u32 msk;
+	union {
+		int counter_idx; /* fixed counters */
+		int event_idx; /* configurable counters */
+	};
+	struct list_head node;
+};
+
+#define CPMU_MAX_COUNTERS 64
+struct cpmu_info {
+	struct pmu pmu;
+	void __iomem *base;
+	struct perf_event **hw_events;
+	struct list_head events_configurable;
+	struct list_head events_fixed;
+	DECLARE_BITMAP(used_counter_bm, CPMU_MAX_COUNTERS);
+	DECLARE_BITMAP(conf_counter_bm, CPMU_MAX_COUNTERS);
+	u16 counter_width;
+	u8 num_counters;
+	u8 num_event_capabilities;
+	int on_cpu;
+	struct hlist_node node;
+	bool freeze_for_enable;
+	bool filter_hdm;
+	int irq;
+};
+
+#define pmu_to_cpmu_info(_pmu) container_of(_pmu, struct cpmu_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 cpmu_parse_caps(struct device *dev, struct cpmu_info *info)
+{
+	DECLARE_BITMAP(fixed_counter_event_cap_bm, 32) = {0};
+	void __iomem *base = info->base;
+	u64 val, eval;
+	int i;
+
+	val = readq(base + CPMU_CAP_REG);
+	info->freeze_for_enable = FIELD_GET(CPMU_CAP_WRITEABLE_WHEN_FROZEN, val) &
+		FIELD_GET(CPMU_CAP_FREEZE, val);
+	if (!info->freeze_for_enable) {
+		dev_err(dev, "Driver does not support CPMUs that do not support freeze for enable\n");
+		return -ENODEV;
+	}
+
+	info->num_counters = FIELD_GET(CPMU_CAP_NUM_COUNTERS_MSK, val) + 1;
+	info->counter_width = FIELD_GET(CPMU_CAP_COUNTER_WIDTH_MSK, val);
+	info->num_event_capabilities = FIELD_GET(CPMU_CAP_NUM_EVN_CAP_REG_SUP_MSK, val) + 1;
+
+	info->filter_hdm = FIELD_GET(CPMU_CAP_FILTERS_SUP_MSK, val) & CPMU_FILTER_HDM;
+	if (FIELD_GET(CPMU_CAP_INT, val))
+		info->irq = FIELD_GET(CPMU_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 cpmu_event *cpmu_ev;
+		u32 events_msk;
+		u8 group_idx;
+
+		val = readq(base + CPMU_COUNTER_CFG_REG(i));
+
+		if (FIELD_GET(CPMU_COUNTER_CFG_TYPE_MSK, val) ==
+			CPMU_COUNTER_CFG_TYPE_CONFIGURABLE) {
+			set_bit(i, info->conf_counter_bm);
+		}
+
+		if (FIELD_GET(CPMU_COUNTER_CFG_TYPE_MSK, val) !=
+		    CPMU_COUNTER_CFG_TYPE_FIXED_FUN)
+			continue;
+
+		/* In this case we know which fields are const */
+		group_idx = FIELD_GET(CPMU_COUNTER_CFG_EVENT_GRP_ID_IDX_MSK, val);
+		events_msk = FIELD_GET(CPMU_COUNTER_CFG_EVENTS_MSK, val);
+		eval = readq(base + CPMU_EVENT_CAP_REG(group_idx));
+		cpmu_ev = devm_kzalloc(dev, sizeof(*cpmu_ev), GFP_KERNEL);
+		if (!cpmu_ev)
+			return -ENOMEM;
+
+		cpmu_ev->vid = FIELD_GET(CPMU_EVENT_CAP_VENDOR_ID_MSK, eval);
+		cpmu_ev->gid = FIELD_GET(CPMU_EVENT_CAP_GROUP_ID_MSK, eval);
+		/* For a fixed purpose counter use the events mask from the counter CFG */
+		cpmu_ev->msk = events_msk;
+		cpmu_ev->counter_idx = i;
+		/* This list add is never unwound as all entries deleted on remove */
+		list_add(&cpmu_ev->node, &info->events_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, CPMU_MAX_COUNTERS)) {
+		struct cpmu_event *cpmu_ev;
+		int j;
+		/* Walk event capabilities unused by fixed counters */
+		for_each_clear_bit(j, fixed_counter_event_cap_bm,
+				   info->num_event_capabilities) {
+			cpmu_ev = devm_kzalloc(dev, sizeof(*cpmu_ev), GFP_KERNEL);
+			if (!cpmu_ev)
+				return -ENOMEM;
+
+			eval = readq(base + CPMU_EVENT_CAP_REG(j));
+			cpmu_ev->vid = FIELD_GET(CPMU_EVENT_CAP_VENDOR_ID_MSK, eval);
+			cpmu_ev->gid = FIELD_GET(CPMU_EVENT_CAP_GROUP_ID_MSK, eval);
+			cpmu_ev->msk = FIELD_GET(CPMU_EVENT_CAP_SUPPORTED_EVENTS_MSK, eval);
+			cpmu_ev->event_idx = j;
+			list_add(&cpmu_ev->node, &info->events_configurable);
+		}
+	}
+
+	return 0;
+}
+
+static ssize_t cpmu_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 CPMU_PMU_EVENT_ATTR(_name, _vid, _gid, _msk)			\
+	PMU_EVENT_ATTR_ID(_name, cpmu_event_sysfs_show,			\
+			  ((u64)(_vid) << 48) | ((u64)(_gid) << 32) | (u64)(_msk))
+
+/* For CXL spec defined events */
+#define CPMU_PMU_EVENT_CXL_ATTR(_name, _gid, _msk) \
+	CPMU_PMU_EVENT_ATTR(_name, PCI_DVSEC_VENDOR_ID_CXL, _gid, _msk)
+
+static struct attribute *cpmu_event_attrs[] = {
+	CPMU_PMU_EVENT_CXL_ATTR(clock_ticks,			CPMU_GID_CLOCK_TICKS, BIT(0)),
+	/* CXL rev 3.0 Table 3-17 - Device to Host Requests */
+	CPMU_PMU_EVENT_CXL_ATTR(d2h_req_rdcurr,			CPMU_GID_D2H_REQ, BIT(1)),
+	CPMU_PMU_EVENT_CXL_ATTR(d2h_req_rdown,			CPMU_GID_D2H_REQ, BIT(2)),
+	CPMU_PMU_EVENT_CXL_ATTR(d2h_req_rdshared,		CPMU_GID_D2H_REQ, BIT(3)),
+	CPMU_PMU_EVENT_CXL_ATTR(d2h_req_rdany,			CPMU_GID_D2H_REQ, BIT(4)),
+	CPMU_PMU_EVENT_CXL_ATTR(d2h_req_rdownnodata,		CPMU_GID_D2H_REQ, BIT(5)),
+	CPMU_PMU_EVENT_CXL_ATTR(d2h_req_itomwr,			CPMU_GID_D2H_REQ, BIT(6)),
+	CPMU_PMU_EVENT_CXL_ATTR(d2h_req_wrcurr,			CPMU_GID_D2H_REQ, BIT(7)),
+	CPMU_PMU_EVENT_CXL_ATTR(d2h_req_clflush,		CPMU_GID_D2H_REQ, BIT(8)),
+	CPMU_PMU_EVENT_CXL_ATTR(d2h_req_cleanevict,		CPMU_GID_D2H_REQ, BIT(9)),
+	CPMU_PMU_EVENT_CXL_ATTR(d2h_req_dirtyevict,		CPMU_GID_D2H_REQ, BIT(10)),
+	CPMU_PMU_EVENT_CXL_ATTR(d2h_req_cleanevictnodata,	CPMU_GID_D2H_REQ, BIT(11)),
+	CPMU_PMU_EVENT_CXL_ATTR(d2h_req_wowrinv,		CPMU_GID_D2H_REQ, BIT(12)),
+	CPMU_PMU_EVENT_CXL_ATTR(d2h_req_wowrinvf,		CPMU_GID_D2H_REQ, BIT(13)),
+	CPMU_PMU_EVENT_CXL_ATTR(d2h_req_wrinv,			CPMU_GID_D2H_REQ, BIT(14)),
+	CPMU_PMU_EVENT_CXL_ATTR(d2h_req_cacheflushed,		CPMU_GID_D2H_REQ, BIT(16)),
+	/* CXL rev 3.0 Table 3-20 - D2H Repsonse Encodings */
+	CPMU_PMU_EVENT_CXL_ATTR(d2h_rsp_rspihiti,		CPMU_GID_D2H_RSP, BIT(4)),
+	CPMU_PMU_EVENT_CXL_ATTR(d2h_rsp_rspvhitv,		CPMU_GID_D2H_RSP, BIT(6)),
+	CPMU_PMU_EVENT_CXL_ATTR(d2h_rsp_rspihitse,		CPMU_GID_D2H_RSP, BIT(5)),
+	CPMU_PMU_EVENT_CXL_ATTR(d2h_rsp_rspshitse,		CPMU_GID_D2H_RSP, BIT(1)),
+	CPMU_PMU_EVENT_CXL_ATTR(d2h_rsp_rspsfwdm,		CPMU_GID_D2H_RSP, BIT(7)),
+	CPMU_PMU_EVENT_CXL_ATTR(d2h_rsp_rspifwdm,		CPMU_GID_D2H_RSP, BIT(15)),
+	CPMU_PMU_EVENT_CXL_ATTR(d2h_rsp_rspvfwdv,		CPMU_GID_D2H_RSP, BIT(22)),
+	/* CXL rev 3.0 Table 3-21 - CXL.cache - Mapping of H2D Requests to D2H Responses */
+	CPMU_PMU_EVENT_CXL_ATTR(h2d_req_snpdata,		CPMU_GID_H2D_REQ, BIT(1)),
+	CPMU_PMU_EVENT_CXL_ATTR(h2d_req_snpinv,			CPMU_GID_H2D_REQ, BIT(2)),
+	CPMU_PMU_EVENT_CXL_ATTR(h2d_req_snpcur,			CPMU_GID_H2D_REQ, BIT(3)),
+	/* CXL rev 3.0 Table 3-22 - H2D Response Opcode Encodings */
+	CPMU_PMU_EVENT_CXL_ATTR(h2d_rsp_writepull,		CPMU_GID_H2D_RSP, BIT(1)),
+	CPMU_PMU_EVENT_CXL_ATTR(h2d_rsp_go,			CPMU_GID_H2D_RSP, BIT(4)),
+	CPMU_PMU_EVENT_CXL_ATTR(h2d_rsp_gowritepull,		CPMU_GID_H2D_RSP, BIT(5)),
+	CPMU_PMU_EVENT_CXL_ATTR(h2d_rsp_extcmp,			CPMU_GID_H2D_RSP, BIT(6)),
+	CPMU_PMU_EVENT_CXL_ATTR(h2d_rsp_gowritepulldrop,	CPMU_GID_H2D_RSP, BIT(8)),
+	CPMU_PMU_EVENT_CXL_ATTR(h2d_rsp_fastgowritepull,	CPMU_GID_H2D_RSP, BIT(13)),
+	CPMU_PMU_EVENT_CXL_ATTR(h2d_rsp_goerrwritepull,		CPMU_GID_H2D_RSP, BIT(15)),
+	/* CXL rev 3.0 Table 13-5 directly lists these */
+	CPMU_PMU_EVENT_CXL_ATTR(cachedata_d2h_data,		CPMU_GID_CACHE_DATA, BIT(0)),
+	CPMU_PMU_EVENT_CXL_ATTR(cachedata_h2d_data,		CPMU_GID_CACHE_DATA, BIT(1)),
+	/* CXL rev 3.0 Table 3-29 M2S Req Memory Opcodes */
+	CPMU_PMU_EVENT_CXL_ATTR(m2s_req_meminv,			CPMU_GID_M2S_REQ, BIT(0)),
+	CPMU_PMU_EVENT_CXL_ATTR(m2s_req_memrd,			CPMU_GID_M2S_REQ, BIT(1)),
+	CPMU_PMU_EVENT_CXL_ATTR(m2s_req_memrddata,		CPMU_GID_M2S_REQ, BIT(2)),
+	CPMU_PMU_EVENT_CXL_ATTR(m2s_req_memrdfwd,		CPMU_GID_M2S_REQ, BIT(3)),
+	CPMU_PMU_EVENT_CXL_ATTR(m2s_req_memwrfwd,		CPMU_GID_M2S_REQ, BIT(4)),
+	CPMU_PMU_EVENT_CXL_ATTR(m2s_req_memspecrd,		CPMU_GID_M2S_REQ, BIT(8)),
+	CPMU_PMU_EVENT_CXL_ATTR(m2s_req_meminvnt,		CPMU_GID_M2S_REQ, BIT(9)),
+	CPMU_PMU_EVENT_CXL_ATTR(m2s_req_memcleanevict,		CPMU_GID_M2S_REQ, BIT(10)),
+	/* CXL rev 3.0 Table 3-35 M2S RwD Memory Opcodes */
+	CPMU_PMU_EVENT_CXL_ATTR(m2s_rwd_memwr,			CPMU_GID_M2S_RWD, BIT(1)),
+	CPMU_PMU_EVENT_CXL_ATTR(m2s_rwd_memwrptl,		CPMU_GID_M2S_RWD, BIT(2)),
+	CPMU_PMU_EVENT_CXL_ATTR(m2s_rwd_biconflict,		CPMU_GID_M2S_RWD, BIT(4)),
+	/* CXL rev 3.0 Table 3-38 M2S BIRsp Memory Opcodes */
+	CPMU_PMU_EVENT_CXL_ATTR(m2s_birsp_i,			CPMU_GID_M2S_BIRSP, BIT(0)),
+	CPMU_PMU_EVENT_CXL_ATTR(m2s_birsp_s,			CPMU_GID_M2S_BIRSP, BIT(1)),
+	CPMU_PMU_EVENT_CXL_ATTR(m2s_birsp_e,			CPMU_GID_M2S_BIRSP, BIT(2)),
+	CPMU_PMU_EVENT_CXL_ATTR(m2s_birsp_iblk,			CPMU_GID_M2S_BIRSP, BIT(4)),
+	CPMU_PMU_EVENT_CXL_ATTR(m2s_birsp_sblk,			CPMU_GID_M2S_BIRSP, BIT(5)),
+	CPMU_PMU_EVENT_CXL_ATTR(m2s_birsp_eblk,			CPMU_GID_M2S_BIRSP, BIT(6)),
+	/* CXL rev 3.0 Table 3-40 S2M BISnp Opcodes */
+	CPMU_PMU_EVENT_CXL_ATTR(s2m_bisnp_cur,			CPMU_GID_S2M_BISNP, BIT(0)),
+	CPMU_PMU_EVENT_CXL_ATTR(s2m_bisnp_data,			CPMU_GID_S2M_BISNP, BIT(1)),
+	CPMU_PMU_EVENT_CXL_ATTR(s2m_bisnp_inv,			CPMU_GID_S2M_BISNP, BIT(2)),
+	CPMU_PMU_EVENT_CXL_ATTR(s2m_bisnp_curblk,		CPMU_GID_S2M_BISNP, BIT(4)),
+	CPMU_PMU_EVENT_CXL_ATTR(s2m_bisnp_datblk,		CPMU_GID_S2M_BISNP, BIT(5)),
+	CPMU_PMU_EVENT_CXL_ATTR(s2m_bisnp_invblk,		CPMU_GID_S2M_BISNP, BIT(6)),
+	/* CXL rev 3.0 Table 3-43 S2M NDR Opcopdes */
+	CPMU_PMU_EVENT_CXL_ATTR(s2m_ndr_cmp,			CPMU_GID_S2M_NDR, BIT(0)),
+	CPMU_PMU_EVENT_CXL_ATTR(s2m_ndr_cmps,			CPMU_GID_S2M_NDR, BIT(1)),
+	CPMU_PMU_EVENT_CXL_ATTR(s2m_ndr_cmpe,			CPMU_GID_S2M_NDR, BIT(2)),
+	CPMU_PMU_EVENT_CXL_ATTR(s2m_ndr_biconflictack,		CPMU_GID_S2M_NDR, BIT(3)),
+	/* CXL rev 3.0 Table 3-46 S2M DRS opcodes */
+	CPMU_PMU_EVENT_CXL_ATTR(s2m_drs_memdata,		CPMU_GID_S2M_DRS, BIT(0)),
+	CPMU_PMU_EVENT_CXL_ATTR(s2m_drs_memdatanxm,		CPMU_GID_S2M_DRS, BIT(1)),
+	/* CXL rev 3.0 Table 13-5 directly lists these */
+	CPMU_PMU_EVENT_CXL_ATTR(ddr_act,			CPMU_GID_DDR, BIT(0)),
+	CPMU_PMU_EVENT_CXL_ATTR(ddr_pre,			CPMU_GID_DDR, BIT(1)),
+	CPMU_PMU_EVENT_CXL_ATTR(ddr_casrd,			CPMU_GID_DDR, BIT(2)),
+	CPMU_PMU_EVENT_CXL_ATTR(ddr_caswr,			CPMU_GID_DDR, BIT(3)),
+	CPMU_PMU_EVENT_CXL_ATTR(ddr_refresh,			CPMU_GID_DDR, BIT(4)),
+	CPMU_PMU_EVENT_CXL_ATTR(ddr_selfrefreshent,		CPMU_GID_DDR, BIT(5)),
+	CPMU_PMU_EVENT_CXL_ATTR(ddr_rfm,			CPMU_GID_DDR, BIT(6)),
+	NULL
+};
+
+static struct cpmu_event *cpmu_find_fixed_counter_event(struct cpmu_info *info,
+							int vid, int gid, int msk)
+{
+	struct cpmu_event *cpmu_ev;
+
+	list_for_each_entry(cpmu_ev, &info->events_fixed, node) {
+		if (vid != cpmu_ev->vid || gid != cpmu_ev->gid)
+			continue;
+
+		/* Precise match for fixed counter */
+		if (msk == cpmu_ev->msk)
+			return cpmu_ev;
+	}
+
+	return ERR_PTR(-EINVAL);
+}
+
+static struct cpmu_event *cpmu_find_config_counter_event(struct cpmu_info *info,
+							 int vid, int gid, int msk)
+{
+	struct cpmu_event *cpmu_ev;
+
+	list_for_each_entry(cpmu_ev, &info->events_configurable, node) {
+		if (vid != cpmu_ev->vid || gid != cpmu_ev->gid)
+			continue;
+
+		/* Request mask must be subset of supported */
+		if (msk & ~cpmu_ev->msk)
+			continue;
+
+		return cpmu_ev;
+	}
+
+	return ERR_PTR(-EINVAL);
+}
+
+static umode_t cpmu_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 cpmu_info *info = dev_get_drvdata(dev);
+	int vid = FIELD_GET(GENMASK_ULL(63, 48), pmu_attr->id);
+	int gid = FIELD_GET(GENMASK_ULL(47, 32), pmu_attr->id);
+	int msk = FIELD_GET(GENMASK_ULL(31, 0), pmu_attr->id);
+
+	if (!IS_ERR(cpmu_find_fixed_counter_event(info, vid, gid, msk)))
+		return attr->mode;
+
+	if (!IS_ERR(cpmu_find_config_counter_event(info, vid, gid, msk)))
+		return attr->mode;
+
+	return 0;
+}
+
+static const struct attribute_group cpmu_events = {
+	.name = "events",
+	.attrs = cpmu_event_attrs,
+	.is_visible = cpmu_event_is_visible,
+};
+
+static ssize_t cpmu_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 CPMU_FORMAT_ATTR(_name, _format)\
+	(&((struct dev_ext_attribute[]) {				\
+		{							\
+			.attr = __ATTR(_name, 0444,			\
+				       cpmu_format_sysfs_show, NULL),	\
+			.var = (void *)_format				\
+		}							  \
+		})[0].attr.attr)
+
+enum {
+	cpmu_mask_attr,
+	cpmu_gid_attr,
+	cpmu_vid_attr,
+	cpmu_threshold_attr,
+	cpmu_invert_attr,
+	cpmu_edge_attr,
+	cpmu_hdm_filter_en_attr,
+	cpmu_hdm_attr,
+};
+
+static struct attribute *cpmu_format_attr[] = {
+	[cpmu_mask_attr] = CPMU_FORMAT_ATTR(mask, "config:0-31"),
+	[cpmu_gid_attr] = CPMU_FORMAT_ATTR(gid, "config:32-47"),
+	[cpmu_vid_attr] = CPMU_FORMAT_ATTR(vid, "config:48-63"),
+	[cpmu_threshold_attr] = CPMU_FORMAT_ATTR(threshold, "config1:0-15"),
+	[cpmu_invert_attr] = CPMU_FORMAT_ATTR(invert, "config1:16"),
+	[cpmu_edge_attr] = CPMU_FORMAT_ATTR(edge, "config1:17"),
+	[cpmu_hdm_filter_en_attr] = CPMU_FORMAT_ATTR(hdm_filter_en, "config1:18"),
+	[cpmu_hdm_attr] = CPMU_FORMAT_ATTR(hdm, "config2:0-15"),
+	NULL
+};
+
+static umode_t cpmu_format_is_visible(struct kobject *kobj, struct attribute *attr, int a)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	struct cpmu_info *info = dev_get_drvdata(dev);
+
+	/*
+	 * Filter capability at the CPMU level, so hide the attributes if the particular
+	 * filter is not supported.
+	 */
+	if (attr == cpmu_format_attr[cpmu_hdm_filter_en_attr] ||
+	    attr == cpmu_format_attr[cpmu_hdm_attr]) {
+		if (info->filter_hdm)
+			return 0444;
+		else
+			return 0;
+	} else {
+		return 0444;
+	}
+}
+
+static const struct attribute_group cpmu_format_group = {
+	.name = "format",
+	.attrs = cpmu_format_attr,
+	.is_visible = cpmu_format_is_visible,
+};
+
+static u32 cpmu_config_get_mask(struct perf_event *event)
+{
+	return FIELD_GET(GENMASK_ULL(31, 0), event->attr.config);
+}
+
+static u16 cpmu_config_get_gid(struct perf_event *event)
+{
+	return FIELD_GET(GENMASK_ULL(47, 32), event->attr.config);
+}
+
+static u16 cpmu_config_get_vid(struct perf_event *event)
+{
+	return FIELD_GET(GENMASK_ULL(63, 48), event->attr.config);
+}
+
+static u8 cpmu_config1_get_threshold(struct perf_event *event)
+{
+	return FIELD_GET(GENMASK_ULL(15, 0), event->attr.config1);
+}
+
+static bool cpmu_config1_get_invert(struct perf_event *event)
+{
+	return FIELD_GET(BIT(16), event->attr.config1);
+}
+
+static bool cpmu_config1_get_edge(struct perf_event *event)
+{
+	return FIELD_GET(BIT(17), 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 cpmu_config1_hdm_filter_en(struct perf_event *event)
+{
+	return FIELD_GET(BIT(14), event->attr.config1);
+}
+
+static u16 cpmu_config2_get_hdm_decoder(struct perf_event *event)
+{
+	return FIELD_GET(GENMASK(15, 0), event->attr.config2);
+}
+
+static ssize_t cpumask_show(struct device *dev, struct device_attribute *attr,
+			    char *buf)
+{
+	struct cpmu_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 *cpmu_cpumask_attrs[] = {
+	&dev_attr_cpumask.attr,
+	NULL
+};
+
+static const struct attribute_group cpmu_cpumask_group = {
+	.attrs = cpmu_cpumask_attrs,
+};
+
+static const struct attribute_group *cpmu_attr_groups[] = {
+	&cpmu_events,
+	&cpmu_format_group,
+	&cpmu_cpumask_group,
+	NULL
+};
+
+/* If counter_idx == NULL, don't try to allocate a counter. */
+static int cpmu_get_event_idx(struct perf_event *event, int *counter_idx, int *event_idx)
+{
+	struct cpmu_info *info = pmu_to_cpmu_info(event->pmu);
+	DECLARE_BITMAP(configurable_and_free, CPMU_MAX_COUNTERS);
+	struct cpmu_event *cpmu_ev;
+	u32 mask;
+	u16 gid, vid;
+	int i;
+
+	vid = cpmu_config_get_vid(event);
+	gid = cpmu_config_get_gid(event);
+	mask = cpmu_config_get_mask(event);
+
+	cpmu_ev = cpmu_find_fixed_counter_event(info, vid, gid, mask);
+	if (!IS_ERR(cpmu_ev)) {
+		if (!counter_idx)
+			return 0;
+		if (!info->hw_events[cpmu_ev->counter_idx]) {
+			*counter_idx = cpmu_ev->counter_idx;
+			return 0;
+		}
+		/* Fixed counter is in use, but maybe a configurable one? */
+	}
+
+	cpmu_ev = cpmu_find_config_counter_event(info, vid, gid, mask);
+	if (!IS_ERR(cpmu_ev)) {
+		if (!counter_idx)
+			return 0;
+
+		bitmap_andnot(configurable_and_free, info->conf_counter_bm,
+			info->used_counter_bm, CPMU_MAX_COUNTERS);
+
+		i = find_first_bit(configurable_and_free, CPMU_MAX_COUNTERS);
+		if (i == CPMU_MAX_COUNTERS)
+			return -EINVAL;
+
+		*counter_idx = i;
+		return 0;
+	}
+
+	return -EINVAL;
+}
+
+static int cpmu_event_init(struct perf_event *event)
+{
+	struct cpmu_info *info = pmu_to_cpmu_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 cpmu_get_event_idx(event, NULL, NULL);
+}
+
+static void cpmu_pmu_enable(struct pmu *pmu)
+{
+	struct cpmu_info *info = pmu_to_cpmu_info(pmu);
+	void __iomem *base = info->base;
+
+	/* We don't have a global enable, but we 'might' have a global freeze which we can use */
+	if (info->freeze_for_enable) {
+		/* Can assume frozen at this stage */
+		writeq(0, base + CPMU_FREEZE_REG);
+
+		return;
+	}
+}
+
+static void cpmu_pmu_disable(struct pmu *pmu)
+{
+	struct cpmu_info *info = pmu_to_cpmu_info(pmu);
+	void __iomem *base = info->base;
+
+	if (info->freeze_for_enable) {
+		/*
+		 * 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(63, 0), base + CPMU_FREEZE_REG);
+		return;
+	}
+}
+
+static void cpmu_event_start(struct perf_event *event, int flags)
+{
+	struct cpmu_info *info = pmu_to_cpmu_info(event->pmu);
+	struct hw_perf_event *hwc = &event->hw;
+	void __iomem *base = info->base;
+	u64 cfg, prev_cnt;
+
+	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 (cpmu_config1_hdm_filter_en(event))
+			cfg = cpmu_config2_get_hdm_decoder(event);
+		else
+			cfg = GENMASK(15, 0);
+		writeq(cfg, base + CPMU_FILTER_CFG_REG(hwc->idx, 0));
+	}
+
+	cfg = readq(base + CPMU_COUNTER_CFG_REG(hwc->idx));
+	cfg |= FIELD_PREP(CPMU_COUNTER_CFG_INT_ON_OVRFLW, 1);
+	cfg |= FIELD_PREP(CPMU_COUNTER_CFG_ENABLE, 1);
+	cfg |= FIELD_PREP(CPMU_COUNTER_CFG_EDGE, cpmu_config1_get_edge(event) ? 1 : 0);
+	cfg |= FIELD_PREP(CPMU_COUNTER_CFG_INVERT, cpmu_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(CPMU_COUNTER_CFG_EVENT_GRP_ID_IDX_MSK, hwc->event_base);
+		cfg |= FIELD_PREP(CPMU_COUNTER_CFG_EVENTS_MSK, cpmu_config_get_mask(event));
+	}
+	cfg &= ~CPMU_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(CPMU_COUNTER_CFG_THRESHOLD_MSK,
+			  cpmu_config1_get_threshold(event));
+	writeq(cfg, base + CPMU_COUNTER_CFG_REG(hwc->idx));
+
+	local64_set(&hwc->prev_count, 0);
+	writeq(0, base + CPMU_COUNTER_REG(hwc->idx));
+
+	if (flags & PERF_EF_RELOAD) {
+		prev_cnt = local64_read(&hwc->prev_count);
+		writeq(prev_cnt, base + CPMU_COUNTER_REG(hwc->idx));
+	}
+
+	perf_event_update_userpage(event);
+}
+
+static u64 cpmu_read_counter(struct perf_event *event)
+{
+	struct cpmu_info *info = pmu_to_cpmu_info(event->pmu);
+	void __iomem *base = info->base;
+
+	return readq(base + CPMU_COUNTER_REG(event->hw.idx));
+}
+
+static void __cpmu_read(struct perf_event *event, bool overflow)
+{
+	struct cpmu_info *info = pmu_to_cpmu_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 = cpmu_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(info->counter_width - 1, 0);
+	if (overflow && delta < GENMASK(info->counter_width - 1, 0))
+		delta += (1UL << info->counter_width);
+
+	local64_add(delta, &event->count);
+}
+
+static void cpmu_read(struct perf_event *event)
+{
+	__cpmu_read(event, false);
+}
+
+static void cpmu_event_stop(struct perf_event *event, int flags)
+{
+	struct cpmu_info *info = pmu_to_cpmu_info(event->pmu);
+	void __iomem *base = info->base;
+	struct hw_perf_event *hwc = &event->hw;
+	u64 cfg;
+
+	cpmu_read(event);
+	WARN_ON_ONCE(hwc->state & PERF_HES_STOPPED);
+	hwc->state |= PERF_HES_STOPPED;
+
+	cfg = readq(base + CPMU_COUNTER_CFG_REG(hwc->idx));
+	cfg &= ~(FIELD_PREP(CPMU_COUNTER_CFG_INT_ON_OVRFLW, 1) |
+		 FIELD_PREP(CPMU_COUNTER_CFG_ENABLE, 1));
+	writeq(cfg, base + CPMU_COUNTER_CFG_REG(hwc->idx));
+
+	if (hwc->state & PERF_HES_UPTODATE)
+		return;
+
+	hwc->state |= PERF_HES_UPTODATE;
+}
+
+/*
+ * Reset ensures no possibility of any information leaking to wrong
+ * counter. Note that all fields written during start()
+ */
+static void cpmu_reset_counter(struct cpmu_info *info, int idx)
+{
+	void __iomem *base = info->base;
+
+	/* Much of this register is read only */
+	writeq(0, base + CPMU_EVENT_CAP_REG(idx));
+	/* Filters are not per counter, so no reset here */
+	writeq(0, base + CPMU_COUNTER_REG(idx));
+}
+
+static int cpmu_event_add(struct perf_event *event, int flags)
+{
+	struct cpmu_info *info = pmu_to_cpmu_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 = cpmu_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);
+
+	cpmu_reset_counter(info, idx);
+
+	if (flags & PERF_EF_START)
+		cpmu_event_start(event, PERF_EF_RELOAD);
+
+	return 0;
+}
+
+static void cpmu_event_del(struct perf_event *event, int flags)
+{
+	struct cpmu_info *info = pmu_to_cpmu_info(event->pmu);
+	struct hw_perf_event *hwc = &event->hw;
+
+	cpmu_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 cpmu_irq(int irq, void *data)
+{
+	struct cpmu_info *info = data;
+	void __iomem *base = info->base;
+	u64 overflowed;
+	DECLARE_BITMAP(overflowedbm, 64);
+	int i;
+
+	overflowed = readq(base + CPMU_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;
+		}
+
+		__cpmu_read(event, true);
+	}
+
+	writeq(overflowed, base + CPMU_OVERFLOW_REG);
+
+	return IRQ_HANDLED;
+}
+
+static int cxl_cpmu_probe(struct device *dev)
+{
+	struct cxl_cpmu *cpmu = to_cxl_cpmu(dev);
+	struct pci_dev *pdev = to_pci_dev(dev->parent);
+	struct cpmu_info *info;
+	char *irq_name;
+	int rc, irq;
+
+	info = devm_kzalloc(dev, sizeof(*info), GFP_KERNEL);
+	if (!info)
+		return -ENOMEM;
+
+	INIT_LIST_HEAD(&info->events_fixed);
+	INIT_LIST_HEAD(&info->events_configurable);
+
+	info->base = cpmu->base;
+
+	info->on_cpu = -1;
+	rc = cpmu_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;
+
+	info->pmu = (struct pmu) {
+		.name = dev_name(dev),
+		.parent = dev,
+		.module = THIS_MODULE,
+		.event_init = cpmu_event_init,
+		.pmu_enable = cpmu_pmu_enable,
+		.pmu_disable = cpmu_pmu_disable,
+		.add = cpmu_event_add,
+		.del = cpmu_event_del,
+		.start = cpmu_event_start,
+		.stop = cpmu_event_stop,
+		.read = cpmu_read,
+		.task_ctx_nr = perf_invalid_context,
+		.attr_groups = cpmu_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(dev));
+	if (!irq_name)
+		return -ENOMEM;
+
+	rc = devm_request_irq(dev, irq, cpmu_irq, IRQF_SHARED, irq_name, info);
+	if (rc)
+		return rc;
+	info->irq = irq;
+
+	rc = cpuhp_state_add_instance(cpmu_cpuhp_state_num, &info->node);
+	if (rc)
+		return rc;
+
+	rc = perf_pmu_register(&info->pmu, info->pmu.name, -1);
+	if (rc)
+		return rc;
+
+	dev_set_drvdata(dev, info);
+
+	return 0;
+}
+
+static void cxl_cpmu_remove(struct device *dev)
+{
+	struct cpmu_info *info = dev_get_drvdata(dev);
+
+	perf_pmu_unregister(&info->pmu);
+	cpuhp_state_remove_instance_nocalls(cpmu_cpuhp_state_num, &info->node);
+}
+
+static struct cxl_driver cxl_cpmu_driver = {
+	.name = "cxl_cpmu",
+	.probe = cxl_cpmu_probe,
+	.remove = cxl_cpmu_remove,
+	.id = CXL_DEVICE_CPMU,
+};
+
+static int cpmu_online_cpu(unsigned int cpu, struct hlist_node *node)
+{
+	struct cpmu_info *info = hlist_entry_safe(node, struct cpmu_info, node);
+
+	if (info->on_cpu != -1)
+		return 0;
+
+	info->on_cpu = cpu;
+	WARN_ON(irq_set_affinity(info->irq, cpumask_of(cpu)));
+
+	return 0;
+}
+
+static int cpmu_offline_cpu(unsigned int cpu, struct hlist_node *node)
+{
+	struct cpmu_info *info = hlist_entry_safe(node, struct cpmu_info, node);
+	unsigned int target;
+
+	if (info->on_cpu != cpu)
+		return 0;
+
+	info->on_cpu = -1;
+	target = cpumask_first(cpu_online_mask);
+	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;
+	WARN_ON(irq_set_affinity(info->irq, cpumask_of(target)));
+
+	return 0;
+}
+
+static __init int cxl_cpmu_init(void)
+{
+	int rc;
+
+	rc = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN,
+				     "AP_PERF_CPMU_ONLINE",
+				     cpmu_online_cpu, cpmu_offline_cpu);
+	if (rc < 0)
+		return rc;
+	cpmu_cpuhp_state_num = rc;
+
+	rc = cxl_driver_register(&cxl_cpmu_driver);
+	if (rc)
+		cpuhp_remove_multi_state(cpmu_cpuhp_state_num);
+
+	return rc;
+}
+
+static __exit void cxl_cpmu_exit(void)
+{
+	cxl_driver_unregister(&cxl_cpmu_driver);
+	cpuhp_remove_multi_state(cpmu_cpuhp_state_num);
+}
+
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS(CXL);
+module_init(cxl_cpmu_init);
+module_exit(cxl_cpmu_exit);
+MODULE_ALIAS_CXL(CXL_DEVICE_CPMU);
