[PATCH v3 2/2] perf x86: Exposing an Uncore unit to PMON for Intel Xeon server platform

[roman . sudarikov]

From: Roman Sudarikov <roman.sudarikov@xxxxxxxxxxxxxxx>

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>/platform_mapping
    in the following format: domain:bus

For example, on a 4-die Intel Xeon server platform:
    $ cat /sys/devices/uncore_iio_0/platform_mapping
    0000:00,0000:40,0000:80,0000:c0

Which means:
IIO PMON block 0 on die 0 belongs to IIO stack on bus 0x00, domain 0x0000
IIO PMON block 0 on die 1 belongs to IIO stack on bus 0x40, domain 0x0000
IIO PMON block 0 on die 2 belongs to IIO stack on bus 0x80, domain 0x0000
IIO PMON block 0 on die 3 belongs to IIO stack on bus 0xc0, domain 0x0000

Co-developed-by: Alexander Antonov <alexander.antonov@xxxxxxxxx>
Signed-off-by: Alexander Antonov <alexander.antonov@xxxxxxxxx>
Signed-off-by: Roman Sudarikov <roman.sudarikov@xxxxxxxxxxxxxxx>
---
 arch/x86/events/intel/uncore.c       |   2 +-
 arch/x86/events/intel/uncore.h       |   1 +
 arch/x86/events/intel/uncore_snbep.c | 162 +++++++++++++++++++++++++++
 3 files changed, 164 insertions(+), 1 deletion(-)

diff --git a/arch/x86/events/intel/uncore.c b/arch/x86/events/intel/uncore.c
index 2c53ad44b51f..c0d86bc8e786 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 max_dies;
 
 /* mask of cpus that collect uncore events */
 static cpumask_t uncore_cpu_mask;
diff --git a/arch/x86/events/intel/uncore.h b/arch/x86/events/intel/uncore.h
index f52dd3f112a7..94eacca6f485 100644
--- a/arch/x86/events/intel/uncore.h
+++ b/arch/x86/events/intel/uncore.h
@@ -523,6 +523,7 @@ extern raw_spinlock_t pci2phy_map_lock;
 extern struct list_head pci2phy_map_head;
 extern struct pci_extra_dev *uncore_extra_pci_dev;
 extern struct event_constraint uncore_constraint_empty;
+extern int max_dies;
 
 /* uncore_snb.c */
 int snb_uncore_pci_init(void);
diff --git a/arch/x86/events/intel/uncore_snbep.c b/arch/x86/events/intel/uncore_snbep.c
index b10a5ec79e48..2562fde2e5b8 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 â Return the bus number BIOS assigned
+ *                       CPUBUSNO(5). (RO)
+ * |[39:32]|    00h    | BUS_NUM_4 â Return the bus number BIOS assigned
+ *                       CPUBUSNO(4). (RO)
+ * |[31:24]|    00h    | BUS_NUM_3 â Return the bus number BIOS assigned
+ *                       CPUBUSNO(3). (RO)
+ * |[23:16]|    00h    | BUS_NUM_2 â Return the bus number BIOS assigned
+ *                       CPUBUSNO(2). (RO)
+ * |[15:8] |    00h    | BUS_NUM_1 â Return the bus number BIOS assigned
+ *                       CPUBUSNO(1). (RO)
+ * | [7:0] |    00h    | BUS_NUM_0 â 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)
@@ -3580,6 +3604,9 @@ static struct intel_uncore_ops skx_uncore_iio_ops = {
 	.read_counter		= uncore_msr_read_counter,
 };
 
+static int skx_iio_get_topology(struct intel_uncore_type *type);
+static int skx_iio_set_mapping(struct intel_uncore_type *type);
+
 static struct intel_uncore_type skx_uncore_iio = {
 	.name			= "iio",
 	.num_counters		= 4,
@@ -3594,6 +3621,8 @@ 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,
+	.get_topology		= skx_iio_get_topology,
+	.set_mapping		= skx_iio_set_mapping,
 };
 
 enum perf_uncore_iio_freerunning_type_id {
@@ -3780,6 +3809,139 @@ static int skx_count_chabox(void)
 	return hweight32(val);
 }
 
+static inline 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 -1;
+
+	*topology = msr_value;
+
+	return 0;
+}
+
+static int skx_iio_get_topology(struct intel_uncore_type *type)
+{
+	int ret, cpu, die, current_die;
+	struct pci_bus *bus = NULL;
+
+	/*
+	 * Verified single-segment environments only; disabled for multiple
+	 * segment topologies for now.
+	 */
+	while ((bus = pci_find_next_bus(bus)) && !pci_domain_nr(bus))
+		;
+	if (bus) {
+		pr_info("I/O stack mapping is not supported for multi-seg\n");
+		return -1;
+	}
+
+	type->topology = kzalloc(max_dies * sizeof(u64), GFP_KERNEL);
+	if (!type->topology)
+		return -ENOMEM;
+
+	/*
+	 * Using cpus_read_lock() to ensure cpu is not going down between
+	 * looking at cpu_online_mask.
+	 */
+	cpus_read_lock();
+	/* Invalid value to start loop.*/
+	current_die = -1;
+	for_each_online_cpu(cpu) {
+		die = topology_logical_die_id(cpu);
+		if (current_die == die)
+			continue;
+		ret = skx_msr_cpu_bus_read(cpu, &type->topology[die]);
+		if (ret) {
+			kfree(type->topology);
+			break;
+		}
+		current_die = die;
+	}
+	cpus_read_unlock();
+
+	return ret;
+}
+
+static inline u8 skx_iio_stack_bus(struct intel_uncore_pmu *pmu, int die)
+{
+	return pmu->type->topology[die] >> (pmu->pmu_idx * BUS_NUM_STRIDE);
+}
+
+static int skx_iio_set_box_mapping(struct intel_uncore_pmu *pmu)
+{
+	char *buf;
+	int die = 0;
+	/* Length of template "%04x:%02x," without null character. */
+	const int template_len = 8;
+
+	/*
+	 * Root bus 0x00 is valid only for die 0 AND pmu_idx = 0.
+	 * Set "0" platform mapping for PMUs which have zero stack bus and
+	 * non-zero index.
+	 */
+	if (!skx_iio_stack_bus(pmu, die) && pmu->pmu_idx) {
+		pmu->mapping = kzalloc(2, GFP_KERNEL);
+		if (!pmu->mapping)
+			return -ENOMEM;
+		sprintf(pmu->mapping, "0");
+		return 0;
+	}
+
+	pmu->mapping = kzalloc(max_dies * template_len + 1, GFP_KERNEL);
+	if (!pmu->mapping)
+		return -ENOMEM;
+
+	buf = pmu->mapping;
+	for (; die < max_dies; die++) {
+		buf += snprintf(buf, template_len + 1, "%04x:%02x,", 0,
+				skx_iio_stack_bus(pmu, die));
+	}
+
+	*(--buf) = '\0';
+
+	return 0;
+}
+
+static int skx_iio_set_mapping(struct intel_uncore_type *type)
+{
+	/*
+	 * Each IIO stack (PCIe root port) has its own IIO PMON block, so each
+	 * platform_mapping holds bus number(s) of PCIe root port(s), 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 platform_mapping
+	 * of IIO PMON block 0 holds "0000:00,0000:40,0000:80,0000:c0":
+	 *
+	 * $ cat /sys/devices/uncore_iio_0/platform_mapping
+	 * 0000:00,0000:40,0000:80,0000:c0
+	 *
+	 * Which means:
+	 * IIO PMON 0 on die 0 belongs to PCIe RP on bus 0x00, domain 0x0000
+	 * IIO PMON 0 on die 1 belongs to PCIe RP on bus 0x40, domain 0x0000
+	 * IIO PMON 0 on die 2 belongs to PCIe RP on bus 0x80, domain 0x0000
+	 * IIO PMON 0 on die 3 belongs to PCIe RP on bus 0xc0, domain 0x0000
+	 */
+
+	int ret;
+	struct intel_uncore_pmu *pmu = type->pmus;
+
+	for (; pmu - type->pmus < type->num_boxes; pmu++) {
+		ret = skx_iio_set_box_mapping(pmu);
+		if (ret) {
+			for (; pmu->pmu_idx > 0; --pmu)
+				kfree(pmu->mapping);
+			break;
+		}
+	}
+
+	kfree(type->topology);
+	return ret;
+}
+
 void skx_uncore_cpu_init(void)
 {
 	skx_uncore_chabox.num_boxes = skx_count_chabox();
-- 
2.19.1