powerpc/hv_gpci: Add sysfs file inside hv_gpci device to show affinity domain via...

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.

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.c file.

Reviewed-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Signed-off-by: Kajol Jain <kjain@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230729073455.7918-6-kjain@linux.ibm.com

diff --git a/arch/powerpc/perf/hv-gpci.c b/arch/powerpc/perf/hv-gpci.c
index 73f2ed42705a59b1627d198b4316fb60f8abc820..de2e1aee9e2cd6710e25e40cf0561666af719d20 100644 (file)
--- a/arch/powerpc/perf/hv-gpci.c
+++ b/arch/powerpc/perf/hv-gpci.c
@@ -105,17 +105,20 @@ static ssize_t cpumask_show(struct device *dev,
 /* 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
 
 /* Counter request value to retrieve system information */
 enum {
        PROCESSOR_BUS_TOPOLOGY,
-       PROCESSOR_CONFIG
+       PROCESSOR_CONFIG,
+       AFFINITY_DOMAIN_VIA_VP, /* affinity domain via virtual processor */
 };
 
 static int sysinfo_counter_request[] = {
        [PROCESSOR_BUS_TOPOLOGY] = 0xD0,
        [PROCESSOR_CONFIG] = 0x90,
+       [AFFINITY_DOMAIN_VIA_VP] = 0xA0,
 };
 
 static DEFINE_PER_CPU(char, hv_gpci_reqb[HGPCI_REQ_BUFFER_SIZE]) __aligned(sizeof(uint64_t));
@@ -316,6 +319,76 @@ out:
        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(sysinfo_counter_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(sysinfo_counter_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);
 
@@ -342,6 +415,11 @@ 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,
 };
 
@@ -592,6 +670,10 @@ static struct device_attribute *sysinfo_device_attr_create(int
                        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;
                }
        } else
                pr_devel("hcall failed, with error: 0x%lx\n", ret);