[PATCH v6 0/3] perf x86: Exposing IO stack to IO PMON mapping through sysfs

[PATCH v6 0/3] perf x86: Exposing IO stack to IO PMON mapping through sysfs

[roman.sudarikov]

From: Roman Sudarikov <roman.sudarikov@linux.intel.com>

The previous version can be found at:
v5: https://lkml.kernel.org/r/20200211161549.19828-1-roman.sudarikov@linux.intel.com/

Changes in this revision are:
v5 -> v6:
  1. Changed the mapping attribute name to "dieX"
  2. Called sysfs_attr_init() prior to dynamically creating the mapping attrs
  3. Removed redundant "empty" attribute
  4. Got an agreement on the mapping attribute format

The previous version can be found at:
v4: https://lkml.kernel.org/r/20200117133759.5729-1-roman.sudarikov@linux.intel.com/

Changes in this revision are:
v4 -> v5:
- Addressed comments from Greg Kroah-Hartman:
  1. Using the attr_update flow for newly introduced optional attributes
  2. No subfolder, optional attributes are created the same level as 'cpumask'
  3. No symlinks, optional attributes are created as files
  4. Single file for each IIO PMON block to node mapping
  5. Added Documentation/ABI/sysfs-devices-mapping

The previous version can be found at:
v3: https://lkml.kernel.org/r/20200113135444.12027-1-roman.sudarikov@linux.intel.com

Changes in this revision are:
v3 -> v4:
- Addressed comments from Greg Kroah-Hartman:
  1. Reworked handling of newly introduced attribute.
  2. Required Documentation update is expected in the follow up patchset

The previous version can be found at:
v2: https://lkml.kernel.org/r/20191210091451.6054-1-roman.sudarikov@linux.intel.com

Changes in this revision are:
v2 -> v3:
  1. Addressed comments from Peter and Kan

The previous version can be found at:
v1: https://lkml.kernel.org/r/20191126163630.17300-1-roman.sudarikov@linux.intel.com

Changes in this revision are:
v1 -> v2:
  1. Fixed process related issues;
  2. This patch set includes kernel support for IIO stack to PMON mapping;
  3. Stephane raised concerns regarding output format which may require
code changes in the user space part of the feature only. We will continue
output format discussion in the context of user space update.

Intel® Xeon® Scalable processor family (code name Skylake-SP) makes
significant changes in the integrated I/O (IIO) architecture. The new
solution introduces IIO stacks which are responsible for managing traffic
between the PCIe domain and the Mesh domain. Each IIO stack has its own
PMON block and can handle either DMI port, x16 PCIe root port, MCP-Link
or various built-in accelerators. IIO PMON blocks allow concurrent
monitoring of I/O flows up to 4 x4 bifurcation within each IIO stack.

Software is supposed to program required perf counters within each IIO
stack and gather performance data. The tricky thing here is that IIO PMON
reports data per IIO stack but users have no idea what IIO stacks are -
they only know devices which are connected to the platform.

Understanding IIO stack concept to find which IIO stack that particular
IO device is connected to, or to identify an IIO PMON block to program
for monitoring specific IIO stack assumes a lot of implicit knowledge
about given Intel server platform architecture.

This patch set introduces:
1. An infrastructure for exposing an Uncore unit to Uncore PMON mapping
   through sysfs-backend;
2. A new --iiostat mode in perf stat to provide I/O performance metrics
   per I/O device.

Usage examples:

1. List all devices below IIO stacks
  ./perf stat --iiostat=show

Sample output w/o libpci:

    S0-RootPort0-uncore_iio_0<00:00.0>
    S1-RootPort0-uncore_iio_0<81:00.0>
    S0-RootPort1-uncore_iio_1<18:00.0>
    S1-RootPort1-uncore_iio_1<86:00.0>
    S1-RootPort1-uncore_iio_1<88:00.0>
    S0-RootPort2-uncore_iio_2<3d:00.0>
    S1-RootPort2-uncore_iio_2<af:00.0>
    S1-RootPort3-uncore_iio_3<da:00.0>

Sample output with libpci:

    S0-RootPort0-uncore_iio_0<00:00.0 Sky Lake-E DMI3 Registers>
    S1-RootPort0-uncore_iio_0<81:00.0 Ethernet Controller X710 for 10GbE SFP+>
    S0-RootPort1-uncore_iio_1<18:00.0 Omni-Path HFI Silicon 100 Series [discrete]>
    S1-RootPort1-uncore_iio_1<86:00.0 Ethernet Controller XL710 for 40GbE QSFP+>
    S1-RootPort1-uncore_iio_1<88:00.0 Ethernet Controller XL710 for 40GbE QSFP+>
    S0-RootPort2-uncore_iio_2<3d:00.0 Ethernet Connection X722 for 10GBASE-T>
    S1-RootPort2-uncore_iio_2<af:00.0 Omni-Path HFI Silicon 100 Series [discrete]>
    S1-RootPort3-uncore_iio_3<da:00.0 NVMe Datacenter SSD [Optane]>

2. Collect metrics for all I/O devices below IIO stack

  ./perf stat --iiostat -- dd if=/dev/zero of=/dev/nvme0n1 bs=1M oflag=direct
    357708+0 records in
    357707+0 records out
    375083606016 bytes (375 GB, 349 GiB) copied, 215.381 s, 1.7 GB/s

  Performance counter stats for 'system wide':

     device             Inbound Read(MB)    Inbound Write(MB)    Outbound Read(MB)   Outbound Write(MB)
    00:00.0                    0                    0                    0                    0
    81:00.0                    0                    0                    0                    0
    18:00.0                    0                    0                    0                    0
    86:00.0                    0                    0                    0                    0
    88:00.0                    0                    0                    0                    0
    3b:00.0                    3                    0                    0                    0
    3c:03.0                    3                    0                    0                    0
    3d:00.0                    3                    0                    0                    0
    af:00.0                    0                    0                    0                    0
    da:00.0               358559                   44                    0                   22

    215.383783574 seconds time elapsed


3. Collect metrics for comma separted list of I/O devices

  ./perf stat --iiostat=da:00.0 -- dd if=/dev/zero of=/dev/nvme0n1 bs=1M oflag=direct
    381555+0 records in
    381554+0 records out
    400088457216 bytes (400 GB, 373 GiB) copied, 374.044 s, 1.1 GB/s

  Performance counter stats for 'system wide':

     device             Inbound Read(MB)    Inbound Write(MB)    Outbound Read(MB)   Outbound Write(MB)
    da:00.0               382462                   47                    0                   23

    374.045775505 seconds time elapsed

Roman Sudarikov (3):
  perf x86: Infrastructure for exposing an Uncore unit to PMON mapping
  perf x86: Topology max dies for whole system
  perf x86: Exposing an Uncore unit to PMON for Intel Xeon® server
    platform

 .../ABI/testing/sysfs-devices-mapping         |  33 +++
 arch/x86/events/intel/uncore.c                |  18 +-
 arch/x86/events/intel/uncore.h                |   8 +
 arch/x86/events/intel/uncore_snbep.c          | 189 ++++++++++++++++++
 4 files changed, 242 insertions(+), 6 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-devices-mapping


base-commit: bb6d3fb354c5ee8d6bde2d576eb7220ea09862b9
-- 
2.19.1

[PATCH v6 1/3] perf x86: Infrastructure for exposing an Uncore unit to PMON mapping

[roman.sudarikov]

From: Roman Sudarikov <roman.sudarikov@linux.intel.com>

Intel® Xeon® Scalable processor family (code name Skylake-SP) makes
significant changes in the integrated I/O (IIO) architecture. The new
solution introduces IIO stacks which are responsible for managing traffic
between the PCIe domain and the Mesh domain. Each IIO stack has its own
PMON block and can handle either DMI port, x16 PCIe root port, MCP-Link
or various built-in accelerators. IIO PMON blocks allow concurrent
monitoring of I/O flows up to 4 x4 bifurcation within each IIO stack.

Software is supposed to program required perf counters within each IIO
stack and gather performance data. The tricky thing here is that IIO PMON
reports data per IIO stack but users have no idea what IIO stacks are -
they only know devices which are connected to the platform.

Understanding IIO stack concept to find which IIO stack that particular
IO device is connected to, or to identify an IIO PMON block to program
for monitoring specific IIO stack assumes a lot of implicit knowledge
about given Intel server platform architecture.

Usage example:
    ls /sys/devices/uncore_<type>_<pmu_idx>/die*

Each Uncore unit type, by its nature, can be mapped to its own context,
for example:
1. CHA - each uncore_cha_<pmu_idx> is assigned to manage a distinct slice
   of LLC capacity;
2. UPI - each uncore_upi_<pmu_idx> is assigned to manage one link of Intel
   UPI Subsystem;
3. IIO - each uncore_iio_<pmu_idx> is assigned to manage one stack of the
   IIO module;
4. IMC - each uncore_imc_<pmu_idx> is assigned to manage one channel of
   Memory Controller.

Implementation details:
Optional callback added to struct intel_uncore_type to discover and map
Uncore units to PMONs:
    int (*set_mapping)(struct intel_uncore_type *type)

Details of IIO Uncore unit mapping to IIO PMON:
Each IIO stack is either DMI port, x16 PCIe root port, MCP-Link or various
built-in accelerators. For Uncore IIO Unit type, the mapping file
holds bus numbers of devices, which can be monitored by that IIO PMON block
on each die.

Co-developed-by: Alexander Antonov <alexander.antonov@intel.com>
Signed-off-by: Alexander Antonov <alexander.antonov@intel.com>
Signed-off-by: Roman Sudarikov <roman.sudarikov@linux.intel.com>
---
 arch/x86/events/intel/uncore.c | 5 +++++
 arch/x86/events/intel/uncore.h | 5 +++++
 2 files changed, 10 insertions(+)

diff --git a/arch/x86/events/intel/uncore.c b/arch/x86/events/intel/uncore.c
index 86467f85c383..98ab8539f126 100644
--- a/arch/x86/events/intel/uncore.c
+++ b/arch/x86/events/intel/uncore.c
@@ -843,10 +843,12 @@ static int uncore_pmu_register(struct intel_uncore_pmu *pmu)
 			.read		= uncore_pmu_event_read,
 			.module		= THIS_MODULE,
 			.capabilities	= PERF_PMU_CAP_NO_EXCLUDE,
+			.attr_update	= pmu->type->attr_update,
 		};
 	} else {
 		pmu->pmu = *pmu->type->pmu;
 		pmu->pmu.attr_groups = pmu->type->attr_groups;
+		pmu->pmu.attr_update = pmu->type->attr_update;
 	}
 
 	if (pmu->type->num_boxes == 1) {
@@ -954,6 +956,9 @@ static int __init uncore_type_init(struct intel_uncore_type *type, bool setid)
 
 	type->pmu_group = &uncore_pmu_attr_group;
 
+	if (type->set_mapping)
+		type->set_mapping(type);
+
 	return 0;
 
 err:
diff --git a/arch/x86/events/intel/uncore.h b/arch/x86/events/intel/uncore.h
index bbfdaa720b45..8821f35e32f0 100644
--- a/arch/x86/events/intel/uncore.h
+++ b/arch/x86/events/intel/uncore.h
@@ -72,7 +72,12 @@ struct intel_uncore_type {
 	struct uncore_event_desc *event_descs;
 	struct freerunning_counters *freerunning;
 	const struct attribute_group *attr_groups[4];
+	const struct attribute_group **attr_update;
 	struct pmu *pmu; /* for custom pmu ops */
+	/* PMON's topologies */
+	u64 *topology;
+	/* mapping Uncore units to PMON ranges */
+	int (*set_mapping)(struct intel_uncore_type *type);
 };
 
 #define pmu_group attr_groups[0]
-- 
2.19.1

[PATCH v6 2/3] perf x86: Topology max dies for whole system

[roman.sudarikov]

From: Roman Sudarikov <roman.sudarikov@linux.intel.com>

Helper function to return number of dies on the platform.

Co-developed-by: Alexander Antonov <alexander.antonov@intel.com>
Signed-off-by: Alexander Antonov <alexander.antonov@intel.com>
Signed-off-by: Roman Sudarikov <roman.sudarikov@linux.intel.com>
---
 arch/x86/events/intel/uncore.c | 13 +++++++------
 arch/x86/events/intel/uncore.h |  3 +++
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/arch/x86/events/intel/uncore.c b/arch/x86/events/intel/uncore.c
index 98ab8539f126..e6297fe42c54 100644
--- a/arch/x86/events/intel/uncore.c
+++ b/arch/x86/events/intel/uncore.c
@@ -16,7 +16,7 @@ struct pci_driver *uncore_pci_driver;
 DEFINE_RAW_SPINLOCK(pci2phy_map_lock);
 struct list_head pci2phy_map_head = LIST_HEAD_INIT(pci2phy_map_head);
 struct pci_extra_dev *uncore_extra_pci_dev;
-static int max_dies;
+int __uncore_max_dies;
 
 /* mask of cpus that collect uncore events */
 static cpumask_t uncore_cpu_mask;
@@ -108,7 +108,7 @@ struct intel_uncore_box *uncore_pmu_to_box(struct intel_uncore_pmu *pmu, int cpu
 	 * The unsigned check also catches the '-1' return value for non
 	 * existent mappings in the topology map.
 	 */
-	return dieid < max_dies ? pmu->boxes[dieid] : NULL;
+	return dieid < uncore_max_dies() ? pmu->boxes[dieid] : NULL;
 }
 
 u64 uncore_msr_read_counter(struct intel_uncore_box *box, struct perf_event *event)
@@ -879,7 +879,7 @@ static void uncore_free_boxes(struct intel_uncore_pmu *pmu)
 {
 	int die;
 
-	for (die = 0; die < max_dies; die++)
+	for (die = 0; die < uncore_max_dies(); die++)
 		kfree(pmu->boxes[die]);
 	kfree(pmu->boxes);
 }
@@ -917,7 +917,7 @@ static int __init uncore_type_init(struct intel_uncore_type *type, bool setid)
 	if (!pmus)
 		return -ENOMEM;
 
-	size = max_dies * sizeof(struct intel_uncore_box *);
+	size = uncore_max_dies() * sizeof(struct intel_uncore_box *);
 
 	for (i = 0; i < type->num_boxes; i++) {
 		pmus[i].func_id	= setid ? i : -1;
@@ -1117,7 +1117,7 @@ static int __init uncore_pci_init(void)
 	size_t size;
 	int ret;
 
-	size = max_dies * sizeof(struct pci_extra_dev);
+	size = uncore_max_dies() * sizeof(struct pci_extra_dev);
 	uncore_extra_pci_dev = kzalloc(size, GFP_KERNEL);
 	if (!uncore_extra_pci_dev) {
 		ret = -ENOMEM;
@@ -1529,7 +1529,8 @@ static int __init intel_uncore_init(void)
 	if (boot_cpu_has(X86_FEATURE_HYPERVISOR))
 		return -ENODEV;
 
-	max_dies = topology_max_packages() * topology_max_die_per_package();
+	__uncore_max_dies =
+		topology_max_packages() * topology_max_die_per_package();
 
 	uncore_init = (struct intel_uncore_init_fun *)id->driver_data;
 	if (uncore_init->pci_init) {
diff --git a/arch/x86/events/intel/uncore.h b/arch/x86/events/intel/uncore.h
index 8821f35e32f0..12bfcb0a8223 100644
--- a/arch/x86/events/intel/uncore.h
+++ b/arch/x86/events/intel/uncore.h
@@ -173,6 +173,9 @@ int uncore_pcibus_to_physid(struct pci_bus *bus);
 ssize_t uncore_event_show(struct kobject *kobj,
 			  struct kobj_attribute *attr, char *buf);
 
+extern int __uncore_max_dies;
+#define uncore_max_dies()	(__uncore_max_dies)
+
 #define INTEL_UNCORE_EVENT_DESC(_name, _config)			\
 {								\
 	.attr	= __ATTR(_name, 0444, uncore_event_show, NULL),	\
-- 
2.19.1

[PATCH v6 3/3] perf x86: Exposing an Uncore unit to PMON for Intel Xeon® server platform

[roman.sudarikov]

From: Roman Sudarikov <roman.sudarikov@linux.intel.com>

Current version supports a server line starting Intel® Xeon® Processor
Scalable Family and introduces mapping for IIO Uncore units only.
Other units can be added on demand.

IIO stack to PMON mapping is exposed through:
    /sys/devices/uncore_iio_<pmu_idx>/dieX
    where dieX is file which holds "Segment:Root Bus" for PCIe root port,
    which can be monitored by that IIO PMON block.

Details are explained in Documentation/ABI/testing/sysfs-devices-mapping

Co-developed-by: Alexander Antonov <alexander.antonov@intel.com>
Signed-off-by: Alexander Antonov <alexander.antonov@intel.com>
Signed-off-by: Roman Sudarikov <roman.sudarikov@linux.intel.com>
---
 .../ABI/testing/sysfs-devices-mapping         |  33 +++
 arch/x86/events/intel/uncore_snbep.c          | 189 ++++++++++++++++++
 2 files changed, 222 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-devices-mapping

diff --git a/Documentation/ABI/testing/sysfs-devices-mapping b/Documentation/ABI/testing/sysfs-devices-mapping
new file mode 100644
index 000000000000..16f4e900be7b
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-devices-mapping
@@ -0,0 +1,33 @@
+What:           /sys/devices/uncore_iio_x/dieX
+Date:           February 2020
+Contact:        Roman Sudarikov <roman.sudarikov@linux.intel.com>
+Description:
+                Each IIO stack (PCIe root port) has its own IIO PMON block, so
+                each dieX file (where X is die number) holds "Segment:Root Bus"
+                for PCIe root port, which can be monitored by that IIO PMON
+                block.
+                For example, on 4-die Xeon platform with up to 6 IIO stacks per
+                die and, therefore, 6 IIO PMON blocks per die, the mapping of
+                IIO PMON block 0 exposes as the following:
+
+                $ ls /sys/devices/uncore_iio_0/die*
+                -r--r--r-- /sys/devices/uncore_iio_0/die0
+                -r--r--r-- /sys/devices/uncore_iio_0/die1
+                -r--r--r-- /sys/devices/uncore_iio_0/die2
+                -r--r--r-- /sys/devices/uncore_iio_0/die3
+
+                $ tail /sys/devices/uncore_iio_0/die*
+                ==> /sys/devices/uncore_iio_0/die0 <==
+                0000:00
+                ==> /sys/devices/uncore_iio_0/die1 <==
+                0000:40
+                ==> /sys/devices/uncore_iio_0/die2 <==
+                0000:80
+                ==> /sys/devices/uncore_iio_0/die3 <==
+                0000:c0
+
+                Which means:
+                IIO PMU 0 on die 0 belongs to PCI RP on bus 0x00, domain 0x0000
+                IIO PMU 0 on die 1 belongs to PCI RP on bus 0x40, domain 0x0000
+                IIO PMU 0 on die 2 belongs to PCI RP on bus 0x80, domain 0x0000
+                IIO PMU 0 on die 3 belongs to PCI RP on bus 0xc0, domain 0x0000
\ No newline at end of file
diff --git a/arch/x86/events/intel/uncore_snbep.c b/arch/x86/events/intel/uncore_snbep.c
index ad20220af303..f805fbdbbe81 100644
--- a/arch/x86/events/intel/uncore_snbep.c
+++ b/arch/x86/events/intel/uncore_snbep.c
@@ -273,6 +273,30 @@
 #define SKX_CPUNODEID			0xc0
 #define SKX_GIDNIDMAP			0xd4
 
+/*
+ * The CPU_BUS_NUMBER MSR returns the values of the respective CPUBUSNO CSR
+ * that BIOS programmed. MSR has package scope.
+ * |  Bit  |  Default  |  Description
+ * | [63]  |    00h    | VALID - When set, indicates the CPU bus
+ *                       numbers have been initialized. (RO)
+ * |[62:48]|    ---    | Reserved
+ * |[47:40]|    00h    | BUS_NUM_5 — Return the bus number BIOS assigned
+ *                       CPUBUSNO(5). (RO)
+ * |[39:32]|    00h    | BUS_NUM_4 — Return the bus number BIOS assigned
+ *                       CPUBUSNO(4). (RO)
+ * |[31:24]|    00h    | BUS_NUM_3 — Return the bus number BIOS assigned
+ *                       CPUBUSNO(3). (RO)
+ * |[23:16]|    00h    | BUS_NUM_2 — Return the bus number BIOS assigned
+ *                       CPUBUSNO(2). (RO)
+ * |[15:8] |    00h    | BUS_NUM_1 — Return the bus number BIOS assigned
+ *                       CPUBUSNO(1). (RO)
+ * | [7:0] |    00h    | BUS_NUM_0 — Return the bus number BIOS assigned
+ *                       CPUBUSNO(0). (RO)
+ */
+#define SKX_MSR_CPU_BUS_NUMBER		0x300
+#define SKX_MSR_CPU_BUS_VALID_BIT	(1ULL << 63)
+#define BUS_NUM_STRIDE			8
+
 /* SKX CHA */
 #define SKX_CHA_MSR_PMON_BOX_FILTER_TID		(0x1ffULL << 0)
 #define SKX_CHA_MSR_PMON_BOX_FILTER_LINK	(0xfULL << 9)
@@ -3575,6 +3599,169 @@ static struct intel_uncore_ops skx_uncore_iio_ops = {
 	.read_counter		= uncore_msr_read_counter,
 };
 
+static inline u8 skx_iio_stack(struct intel_uncore_pmu *pmu, int die)
+{
+	return pmu->type->topology[die] >> (pmu->pmu_idx * BUS_NUM_STRIDE);
+}
+
+static umode_t
+skx_iio_mapping_visible(struct kobject *kobj, struct attribute *attr, int die)
+{
+	struct intel_uncore_pmu *pmu = dev_get_drvdata(kobj_to_dev(kobj));
+
+	//Root bus 0x00 is valid only for die 0 AND pmu_idx = 0.
+	return (!skx_iio_stack(pmu, die) && pmu->pmu_idx) ? 0 : attr->mode;
+}
+
+static ssize_t skx_iio_mapping_show(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct pci_bus *bus = NULL;
+	struct pmu *pmu = dev_get_drvdata(dev);
+	struct intel_uncore_pmu *uncore_pmu =
+		container_of(pmu, struct intel_uncore_pmu, pmu);
+	int pmu_idx = uncore_pmu->pmu_idx;
+
+	struct dev_ext_attribute *ea =
+		container_of(attr, struct dev_ext_attribute, attr);
+	long die = (long)ea->var;
+
+	do {
+		bus = pci_find_next_bus(bus);
+	} while (pmu_idx--);
+
+	return sprintf(buf, "%04x:%02x\n", pci_domain_nr(bus),
+					   skx_iio_stack(uncore_pmu, die));
+}
+
+static int skx_msr_cpu_bus_read(int cpu, u64 *topology)
+{
+	u64 msr_value;
+
+	if (rdmsrl_on_cpu(cpu, SKX_MSR_CPU_BUS_NUMBER, &msr_value) ||
+			!(msr_value & SKX_MSR_CPU_BUS_VALID_BIT))
+		return -ENXIO;
+
+	*topology = msr_value;
+
+	return 0;
+}
+
+static int die_to_cpu(int die)
+{
+	int res = 0, cpu, current_die;
+	/*
+	 * Using cpus_read_lock() to ensure cpu is not going down between
+	 * looking at cpu_online_mask.
+	 */
+	cpus_read_lock();
+	for_each_online_cpu(cpu) {
+		current_die = topology_logical_die_id(cpu);
+		if (current_die == die) {
+			res = cpu;
+			break;
+		}
+	}
+	cpus_read_unlock();
+	return res;
+}
+
+static int skx_iio_get_topology(struct intel_uncore_type *type)
+{
+	int i, ret;
+	struct pci_bus *bus = NULL;
+
+	/*
+	 * Verified single-segment environments only; disabled for multiple
+	 * segment topologies for now except VMD domains.
+	 * VMD domains start at 0x10000 to not clash with ACPI _SEG domains.
+	 */
+	while ((bus = pci_find_next_bus(bus))
+		&& (!pci_domain_nr(bus) || pci_domain_nr(bus) > 0xffff))
+		;
+	if (bus)
+		return -EPERM;
+
+	type->topology = kcalloc(uncore_max_dies(), sizeof(u64), GFP_KERNEL);
+	if (!type->topology)
+		return -ENOMEM;
+
+	for (i = 0; i < uncore_max_dies(); i++) {
+		ret = skx_msr_cpu_bus_read(die_to_cpu(i), &type->topology[i]);
+		if (ret) {
+			kfree(type->topology);
+			type->topology = NULL;
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
+static struct attribute_group skx_iio_mapping_group = {
+	.is_visible	= skx_iio_mapping_visible,
+};
+
+const static struct attribute_group *skx_iio_attr_update[] = {
+	&skx_iio_mapping_group,
+	NULL,
+};
+
+static int skx_iio_set_mapping(struct intel_uncore_type *type)
+{
+	char buf[64];
+	int ret = 0;
+	long die;
+	struct attribute **attrs;
+	struct dev_ext_attribute *eas;
+
+	ret = skx_iio_get_topology(type);
+	if (ret)
+		return ret;
+
+	// One more for NULL.
+	attrs = kzalloc((uncore_max_dies() + 1) * sizeof(*attrs), GFP_KERNEL);
+	if (!attrs) {
+		kfree(type->topology);
+		return -ENOMEM;
+	}
+
+	eas = kzalloc(sizeof(*eas) * uncore_max_dies(), GFP_KERNEL);
+	if (!eas) {
+		kfree(attrs);
+		kfree(type->topology);
+		return -ENOMEM;
+	}
+	for (die = 0; die < uncore_max_dies(); die++) {
+		sprintf(buf, "die%ld", die);
+		sysfs_attr_init(&eas[die].attr.attr);
+		eas[die].attr.attr.name = kstrdup(buf, GFP_KERNEL);
+		if (!eas[die].attr.attr.name) {
+			ret = -ENOMEM;
+			goto err;
+		}
+		eas[die].attr.attr.mode = 0444;
+		eas[die].attr.show = skx_iio_mapping_show;
+		eas[die].attr.store = NULL;
+		eas[die].var = (void *)die;
+		attrs[die] = &eas[die].attr.attr;
+	}
+
+	skx_iio_mapping_group.attrs = attrs;
+
+	return 0;
+
+err:
+	for (; die >= 0; die--)
+		kfree(eas[die].attr.attr.name);
+	kfree(eas);
+	kfree(attrs);
+	kfree(type->topology);
+	type->attr_update = NULL;
+
+	return ret;
+}
+
 static struct intel_uncore_type skx_uncore_iio = {
 	.name			= "iio",
 	.num_counters		= 4,
@@ -3589,6 +3776,8 @@ static struct intel_uncore_type skx_uncore_iio = {
 	.constraints		= skx_uncore_iio_constraints,
 	.ops			= &skx_uncore_iio_ops,
 	.format_group		= &skx_uncore_iio_format_group,
+	.attr_update		= skx_iio_attr_update,
+	.set_mapping		= skx_iio_set_mapping,
 };
 
 enum perf_uncore_iio_freerunning_type_id {
-- 
2.19.1

Re: [PATCH v6 3/3] perf x86: Exposing an Uncore unit to PMON for Intel Xeon® server platform

[Greg KH]

On Thu, Feb 13, 2020 at 06:01:48PM +0300, roman.sudarikov@linux.intel.com wrote:
> From: Roman Sudarikov <roman.sudarikov@linux.intel.com>
> 
> Current version supports a server line starting Intel® Xeon® Processor
> Scalable Family and introduces mapping for IIO Uncore units only.
> Other units can be added on demand.
> 
> IIO stack to PMON mapping is exposed through:
>     /sys/devices/uncore_iio_<pmu_idx>/dieX
>     where dieX is file which holds "Segment:Root Bus" for PCIe root port,
>     which can be monitored by that IIO PMON block.
> 
> Details are explained in Documentation/ABI/testing/sysfs-devices-mapping
> 
> Co-developed-by: Alexander Antonov <alexander.antonov@intel.com>
> Signed-off-by: Alexander Antonov <alexander.antonov@intel.com>
> Signed-off-by: Roman Sudarikov <roman.sudarikov@linux.intel.com>
> ---
>  .../ABI/testing/sysfs-devices-mapping         |  33 +++
>  arch/x86/events/intel/uncore_snbep.c          | 189 ++++++++++++++++++
>  2 files changed, 222 insertions(+)
>  create mode 100644 Documentation/ABI/testing/sysfs-devices-mapping
> 
> diff --git a/Documentation/ABI/testing/sysfs-devices-mapping b/Documentation/ABI/testing/sysfs-devices-mapping
> new file mode 100644
> index 000000000000..16f4e900be7b
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-devices-mapping
> @@ -0,0 +1,33 @@
> +What:           /sys/devices/uncore_iio_x/dieX
> +Date:           February 2020
> +Contact:        Roman Sudarikov <roman.sudarikov@linux.intel.com>
> +Description:
> +                Each IIO stack (PCIe root port) has its own IIO PMON block, so
> +                each dieX file (where X is die number) holds "Segment:Root Bus"
> +                for PCIe root port, which can be monitored by that IIO PMON
> +                block.
> +                For example, on 4-die Xeon platform with up to 6 IIO stacks per
> +                die and, therefore, 6 IIO PMON blocks per die, the mapping of
> +                IIO PMON block 0 exposes as the following:
> +
> +                $ ls /sys/devices/uncore_iio_0/die*
> +                -r--r--r-- /sys/devices/uncore_iio_0/die0
> +                -r--r--r-- /sys/devices/uncore_iio_0/die1
> +                -r--r--r-- /sys/devices/uncore_iio_0/die2
> +                -r--r--r-- /sys/devices/uncore_iio_0/die3
> +
> +                $ tail /sys/devices/uncore_iio_0/die*
> +                ==> /sys/devices/uncore_iio_0/die0 <==
> +                0000:00
> +                ==> /sys/devices/uncore_iio_0/die1 <==
> +                0000:40
> +                ==> /sys/devices/uncore_iio_0/die2 <==
> +                0000:80
> +                ==> /sys/devices/uncore_iio_0/die3 <==
> +                0000:c0
> +
> +                Which means:
> +                IIO PMU 0 on die 0 belongs to PCI RP on bus 0x00, domain 0x0000
> +                IIO PMU 0 on die 1 belongs to PCI RP on bus 0x40, domain 0x0000
> +                IIO PMU 0 on die 2 belongs to PCI RP on bus 0x80, domain 0x0000
> +                IIO PMU 0 on die 3 belongs to PCI RP on bus 0xc0, domain 0x0000
> \ No newline at end of file
> diff --git a/arch/x86/events/intel/uncore_snbep.c b/arch/x86/events/intel/uncore_snbep.c
> index ad20220af303..f805fbdbbe81 100644
> --- a/arch/x86/events/intel/uncore_snbep.c
> +++ b/arch/x86/events/intel/uncore_snbep.c
> @@ -273,6 +273,30 @@
>  #define SKX_CPUNODEID			0xc0
>  #define SKX_GIDNIDMAP			0xd4
>  
> +/*
> + * The CPU_BUS_NUMBER MSR returns the values of the respective CPUBUSNO CSR
> + * that BIOS programmed. MSR has package scope.
> + * |  Bit  |  Default  |  Description
> + * | [63]  |    00h    | VALID - When set, indicates the CPU bus
> + *                       numbers have been initialized. (RO)
> + * |[62:48]|    ---    | Reserved
> + * |[47:40]|    00h    | BUS_NUM_5 — Return the bus number BIOS assigned
> + *                       CPUBUSNO(5). (RO)
> + * |[39:32]|    00h    | BUS_NUM_4 — Return the bus number BIOS assigned
> + *                       CPUBUSNO(4). (RO)
> + * |[31:24]|    00h    | BUS_NUM_3 — Return the bus number BIOS assigned
> + *                       CPUBUSNO(3). (RO)
> + * |[23:16]|    00h    | BUS_NUM_2 — Return the bus number BIOS assigned
> + *                       CPUBUSNO(2). (RO)
> + * |[15:8] |    00h    | BUS_NUM_1 — Return the bus number BIOS assigned
> + *                       CPUBUSNO(1). (RO)
> + * | [7:0] |    00h    | BUS_NUM_0 — Return the bus number BIOS assigned
> + *                       CPUBUSNO(0). (RO)
> + */
> +#define SKX_MSR_CPU_BUS_NUMBER		0x300
> +#define SKX_MSR_CPU_BUS_VALID_BIT	(1ULL << 63)
> +#define BUS_NUM_STRIDE			8
> +
>  /* SKX CHA */
>  #define SKX_CHA_MSR_PMON_BOX_FILTER_TID		(0x1ffULL << 0)
>  #define SKX_CHA_MSR_PMON_BOX_FILTER_LINK	(0xfULL << 9)
> @@ -3575,6 +3599,169 @@ static struct intel_uncore_ops skx_uncore_iio_ops = {
>  	.read_counter		= uncore_msr_read_counter,
>  };
>  
> +static inline u8 skx_iio_stack(struct intel_uncore_pmu *pmu, int die)
> +{
> +	return pmu->type->topology[die] >> (pmu->pmu_idx * BUS_NUM_STRIDE);
> +}
> +
> +static umode_t
> +skx_iio_mapping_visible(struct kobject *kobj, struct attribute *attr, int die)
> +{
> +	struct intel_uncore_pmu *pmu = dev_get_drvdata(kobj_to_dev(kobj));
> +
> +	//Root bus 0x00 is valid only for die 0 AND pmu_idx = 0.
> +	return (!skx_iio_stack(pmu, die) && pmu->pmu_idx) ? 0 : attr->mode;
> +}
> +
> +static ssize_t skx_iio_mapping_show(struct device *dev,
> +				struct device_attribute *attr, char *buf)
> +{
> +	struct pci_bus *bus = NULL;
> +	struct pmu *pmu = dev_get_drvdata(dev);
> +	struct intel_uncore_pmu *uncore_pmu =
> +		container_of(pmu, struct intel_uncore_pmu, pmu);
> +	int pmu_idx = uncore_pmu->pmu_idx;
> +
> +	struct dev_ext_attribute *ea =
> +		container_of(attr, struct dev_ext_attribute, attr);
> +	long die = (long)ea->var;

Why the extra blank line in the middle of the variable list?

And can't you make proper macros for the pmu and attribute container_of
calls?

> +
> +	do {
> +		bus = pci_find_next_bus(bus);
> +	} while (pmu_idx--);

I'm dense, but what are you doing here?  Just walking the list of pci
busses for a specific number of them?  What guarantees any ordering of
pci busses in this list?  What happens if you get a new bus hotplugged
in the middle of this loop?  Or yanked out?  How will pmu_idx mean
anything then?

And what does pmu_idx mean anyway?  Why not just store the real pointer
to the pci bus in your structure properly, so you don't have to do odd
things like guess the ordering of the pci busses in the system?  As that
way lies dragons...

> +
> +	return sprintf(buf, "%04x:%02x\n", pci_domain_nr(bus),
> +					   skx_iio_stack(uncore_pmu, die));
> +}
> +
> +static int skx_msr_cpu_bus_read(int cpu, u64 *topology)
> +{
> +	u64 msr_value;
> +
> +	if (rdmsrl_on_cpu(cpu, SKX_MSR_CPU_BUS_NUMBER, &msr_value) ||
> +			!(msr_value & SKX_MSR_CPU_BUS_VALID_BIT))
> +		return -ENXIO;
> +
> +	*topology = msr_value;
> +
> +	return 0;
> +}
> +
> +static int die_to_cpu(int die)
> +{
> +	int res = 0, cpu, current_die;
> +	/*
> +	 * Using cpus_read_lock() to ensure cpu is not going down between
> +	 * looking at cpu_online_mask.
> +	 */

checkpatch didn't complain about this?


> +	cpus_read_lock();
> +	for_each_online_cpu(cpu) {
> +		current_die = topology_logical_die_id(cpu);
> +		if (current_die == die) {
> +			res = cpu;
> +			break;
> +		}
> +	}
> +	cpus_read_unlock();
> +	return res;
> +}
> +
> +static int skx_iio_get_topology(struct intel_uncore_type *type)
> +{
> +	int i, ret;
> +	struct pci_bus *bus = NULL;
> +
> +	/*
> +	 * Verified single-segment environments only; disabled for multiple
> +	 * segment topologies for now except VMD domains.
> +	 * VMD domains start at 0x10000 to not clash with ACPI _SEG domains.
> +	 */
> +	while ((bus = pci_find_next_bus(bus))
> +		&& (!pci_domain_nr(bus) || pci_domain_nr(bus) > 0xffff))
> +		;
> +	if (bus)
> +		return -EPERM;
> +
> +	type->topology = kcalloc(uncore_max_dies(), sizeof(u64), GFP_KERNEL);
> +	if (!type->topology)
> +		return -ENOMEM;
> +
> +	for (i = 0; i < uncore_max_dies(); i++) {
> +		ret = skx_msr_cpu_bus_read(die_to_cpu(i), &type->topology[i]);
> +		if (ret) {
> +			kfree(type->topology);
> +			type->topology = NULL;
> +			return ret;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static struct attribute_group skx_iio_mapping_group = {
> +	.is_visible	= skx_iio_mapping_visible,
> +};
> +
> +const static struct attribute_group *skx_iio_attr_update[] = {
> +	&skx_iio_mapping_group,
> +	NULL,
> +};
> +
> +static int skx_iio_set_mapping(struct intel_uncore_type *type)
> +{
> +	char buf[64];
> +	int ret = 0;
> +	long die;
> +	struct attribute **attrs;
> +	struct dev_ext_attribute *eas;
> +
> +	ret = skx_iio_get_topology(type);
> +	if (ret)
> +		return ret;
> +
> +	// One more for NULL.
> +	attrs = kzalloc((uncore_max_dies() + 1) * sizeof(*attrs), GFP_KERNEL);
> +	if (!attrs) {
> +		kfree(type->topology);
> +		return -ENOMEM;
> +	}
> +
> +	eas = kzalloc(sizeof(*eas) * uncore_max_dies(), GFP_KERNEL);
> +	if (!eas) {
> +		kfree(attrs);
> +		kfree(type->topology);
> +		return -ENOMEM;

gotos are your friend, please use them.

> +	}
> +	for (die = 0; die < uncore_max_dies(); die++) {
> +		sprintf(buf, "die%ld", die);
> +		sysfs_attr_init(&eas[die].attr.attr);
> +		eas[die].attr.attr.name = kstrdup(buf, GFP_KERNEL);

Who ends up freeing this string and overall attribute when things get
torn down if something is removed from the system, or the module is
unloaded, or something else like that?

thanks,

greg k-h