[PATCH 05/10] powerpc/hv_gpci: Add sysfs file inside hv_gpci device to show affinity domain via virtual processor information

[Kajol Jain]

The hcall H_GET_PERF_COUNTER_INFO with counter request value as
AFFINITY_DOMAIN_INFORMATION_BY_VIRTUAL_PROCESSOR(0XA0), can be used to get
the system affinity domain via virtual processor information. To expose
the system affinity domain via virtual processor information, patch adds
sysfs file called "affinity_domain_via_virtual_processor" to the
"/sys/devices/hv_gpci/interface/" of hv_gpci pmu driver.

Add macro for AFFINITY_DOMAIN_VIA_VP, which points to counter request value
for "affinity_domain_via_virtual_processor" in hv-gpci.h file.

The affinity_domain_via_virtual_processor sysfs file is only available for
power10 and above platforms. Add a macro called
INTERFACE_AFFINITY_DOMAIN_VIA_VP_ATTR, which points to the index of NULL
placeholder, for affinity_domain_via_virtual_processor attribute in
interface_attrs array. Also updated the value of INTERFACE_NULL_ATTR macro
in hv-gpci.h file.

Signed-off-by: Kajol Jain <kjain at linux.ibm.com>
---
 arch/powerpc/perf/hv-gpci.c | 84 +++++++++++++++++++++++++++++++++++++
 arch/powerpc/perf/hv-gpci.h |  4 +-
 2 files changed, 87 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/perf/hv-gpci.c b/arch/powerpc/perf/hv-gpci.c
index c9fe74373e5f..cac726f06221 100644
--- a/arch/powerpc/perf/hv-gpci.c
+++ b/arch/powerpc/perf/hv-gpci.c
@@ -303,6 +303,75 @@ static ssize_t processor_config_show(struct device *dev, struct device_attribute
 	return ret;
 }
 
+static ssize_t affinity_domain_via_virtual_processor_show(struct device *dev,
+			struct device_attribute *attr, char *buf)
+{
+	struct hv_gpci_request_buffer *arg;
+	unsigned long ret;
+	size_t n = 0;
+
+	arg = (void *)get_cpu_var(hv_gpci_reqb);
+	memset(arg, 0, HGPCI_REQ_BUFFER_SIZE);
+
+	/*
+	 * Pass the counter request 0xA0 corresponds to request
+	 * type 'Affinity_domain_information_by_virutal_processor',
+	 * to retrieve the system affinity domain information.
+	 * starting_index value refers to the starting hardware
+	 * processor index.
+	 */
+	ret = systeminfo_gpci_request(AFFINITY_DOMAIN_VIA_VP, 0, 0, buf, &n, arg);
+
+	if (!ret)
+		return n;
+
+	if (ret != H_PARAMETER)
+		goto out;
+
+	/*
+	 * ret value as 'H_PARAMETER' corresponds to 'GEN_BUF_TOO_SMALL', which
+	 * implies that buffer can't accommodate all information, and a partial buffer
+	 * returned. To handle that, we need to take subsequent requests
+	 * with next secondary index to retrieve additional (missing) data.
+	 * Below loop do subsequent hcalls with next secondary index and add it
+	 * to buffer util we get all the information.
+	 */
+	while (ret == H_PARAMETER) {
+		int returned_values = be16_to_cpu(arg->params.returned_values);
+		int elementsize = be16_to_cpu(arg->params.cv_element_size);
+		int last_element = (returned_values - 1) * elementsize;
+
+		/*
+		 * Since the starting index and secondary index type is part of the
+		 * counter_value buffer elements, use the starting index value in the
+		 * last array element as subsequent starting index, and use secondary index
+		 * value in the last array element plus 1 as subsequent secondary index.
+		 * For counter request '0xA0', starting index points to partition id
+		 * and secondary index points to corresponding virtual processor index.
+		 */
+		u32 starting_index = arg->bytes[last_element + 1] + (arg->bytes[last_element] << 8);
+		u16 secondary_index = arg->bytes[last_element + 3] +
+				(arg->bytes[last_element + 2] << 8) + 1;
+
+		memset(arg, 0, HGPCI_REQ_BUFFER_SIZE);
+
+		ret = systeminfo_gpci_request(AFFINITY_DOMAIN_VIA_VP, starting_index,
+					secondary_index, buf, &n, arg);
+
+		if (!ret)
+			return n;
+
+		if (ret != H_PARAMETER)
+			goto out;
+	}
+
+	return n;
+
+out:
+	put_cpu_var(hv_gpci_reqb);
+	return ret;
+}
+
 static DEVICE_ATTR_RO(kernel_version);
 static DEVICE_ATTR_RO(cpumask);
 
@@ -329,6 +398,11 @@ static struct attribute *interface_attrs[] = {
 	 * attribute, set in init function if applicable.
 	 */
 	NULL,
+	/*
+	 * This NULL is a placeholder for the affinity_domain_via_virtual_processor
+	 * attribute, set in init function if applicable.
+	 */
+	NULL,
 	NULL,
 };
 
@@ -561,6 +635,10 @@ static void sysinfo_device_attr_create(int sysinfo_interface_group_index)
 		attr->attr.name = "processor_config";
 		attr->show = processor_config_show;
 	break;
+	case INTERFACE_AFFINITY_DOMAIN_VIA_VP_ATTR:
+		attr->attr.name = "affinity_domain_via_virtual_processor";
+		attr->show = affinity_domain_via_virtual_processor_show;
+	break;
 	}
 
 	attr->attr.mode = 0444;
@@ -574,6 +652,12 @@ static void add_sysinfo_interface_files(void)
 
 	/* Add processor_config attribute in the interface_attrs attribute array */
 	sysinfo_device_attr_create(INTERFACE_PROCESSOR_CONFIG_ATTR);
+
+	/*
+	 * Add affinity_domain_via_virtual_processor attribute in the
+	 * interface_attrs attribute array
+	 */
+	sysinfo_device_attr_create(INTERFACE_AFFINITY_DOMAIN_VIA_VP_ATTR);
 }
 
 static int hv_gpci_init(void)
diff --git a/arch/powerpc/perf/hv-gpci.h b/arch/powerpc/perf/hv-gpci.h
index 0d324a7c684b..c88599fbcaa5 100644
--- a/arch/powerpc/perf/hv-gpci.h
+++ b/arch/powerpc/perf/hv-gpci.h
@@ -26,11 +26,13 @@ enum {
 /* Counter request value to retrieve system information */
 #define PROCESSOR_BUS_TOPOLOGY	0XD0
 #define PROCESSOR_CONFIG	0X90
+#define AFFINITY_DOMAIN_VIA_VP	0xA0 /* affinity domain via virtual processor */
 
 /* Interface attribute array index to store system information */
 #define INTERFACE_PROCESSOR_BUS_TOPOLOGY_ATTR	6
 #define INTERFACE_PROCESSOR_CONFIG_ATTR		7
-#define INTERFACE_NULL_ATTR			8
+#define INTERFACE_AFFINITY_DOMAIN_VIA_VP_ATTR	8
+#define INTERFACE_NULL_ATTR			9
 
 #define REQUEST_FILE "../hv-gpci-requests.h"
 #define NAME_LOWER hv_gpci
-- 
2.35.3