powerpc/hv_gpci: Add sysfs file inside hv_gpci device to show processor config inform...

The hcall H_GET_PERF_COUNTER_INFO with counter request value as
PROCESSOR_CONFIG(0X90), can be used to get the system
processor configuration information. To expose the system
processor config information, patch adds sysfs file called
"processor_config" to the "/sys/devices/hv_gpci/interface/"
of hv_gpci pmu driver.

Add enum and sysinfo_counter_request array to get required
counter request value in hv-gpci.c file.
Also add a new function called "sysinfo_device_attr_create",
which will create and return required device attribute to the
add_sysinfo_interface_files function.

The processor_config sysfs file is only available for power10
and above platforms. Add a new macro called
INTERFACE_PROCESSOR_CONFIG_ATTR, which points to the index of
NULL placefolder, for processor_config attribute in the interface_attrs
array. Also add macro INTERFACE_NULL_ATTR which points to index of NULL
attribute in interface_attrs array.

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/20230729073455.7918-4-kjain@linux.ibm.com

diff --git a/arch/powerpc/perf/hv-gpci.c b/arch/powerpc/perf/hv-gpci.c
index 7ac9cec..73f2ed4 100644 (file)
--- a/arch/powerpc/perf/hv-gpci.c
+++ b/arch/powerpc/perf/hv-gpci.c
@@ -102,11 +102,21 @@ static ssize_t cpumask_show(struct device *dev,
        return cpumap_print_to_pagebuf(true, buf, &hv_gpci_cpumask);
 }
 
-/* Counter request value to retrieve system information */
-#define PROCESSOR_BUS_TOPOLOGY 0XD0
-
 /* 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
+
+/* Counter request value to retrieve system information */
+enum {
+       PROCESSOR_BUS_TOPOLOGY,
+       PROCESSOR_CONFIG
+};
+
+static int sysinfo_counter_request[] = {
+       [PROCESSOR_BUS_TOPOLOGY] = 0xD0,
+       [PROCESSOR_CONFIG] = 0x90,
+};
 
 static DEFINE_PER_CPU(char, hv_gpci_reqb[HGPCI_REQ_BUFFER_SIZE]) __aligned(sizeof(uint64_t));
 
@@ -187,7 +197,8 @@ static ssize_t processor_bus_topology_show(struct device *dev, struct device_att
         * starting_index value implies the starting hardware
         * chip id.
         */
-       ret = systeminfo_gpci_request(PROCESSOR_BUS_TOPOLOGY, 0, 0, buf, &n, arg);
+       ret = systeminfo_gpci_request(sysinfo_counter_request[PROCESSOR_BUS_TOPOLOGY],
+                       0, 0, buf, &n, arg);
 
        if (!ret)
                return n;
@@ -220,8 +231,76 @@ static ssize_t processor_bus_topology_show(struct device *dev, struct device_att
 
                memset(arg, 0, HGPCI_REQ_BUFFER_SIZE);
 
-               ret = systeminfo_gpci_request(PROCESSOR_BUS_TOPOLOGY, starting_index,
-                               0, buf, &n, arg);
+               ret = systeminfo_gpci_request(sysinfo_counter_request[PROCESSOR_BUS_TOPOLOGY],
+                               starting_index, 0, 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 ssize_t processor_config_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 value 0x90 corresponds to request
+        * type 'Processor_config', to retrieve
+        * the system processor information.
+        * starting_index value implies the starting hardware
+        * processor index.
+        */
+       ret = systeminfo_gpci_request(sysinfo_counter_request[PROCESSOR_CONFIG],
+                       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 starting index to retrieve additional (missing) data.
+        * Below loop do subsequent hcalls with next starting 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 is part of counter_value
+                * buffer elements, use the starting index value in the last
+                * element and add 1 to subsequent hcalls.
+                */
+               u32 starting_index = arg->bytes[last_element + 3] +
+                               (arg->bytes[last_element + 2] << 8) +
+                               (arg->bytes[last_element + 1] << 16) +
+                               (arg->bytes[last_element] << 24) + 1;
+
+               memset(arg, 0, HGPCI_REQ_BUFFER_SIZE);
+
+               ret = systeminfo_gpci_request(sysinfo_counter_request[PROCESSOR_CONFIG],
+                               starting_index, 0, buf, &n, arg);
 
                if (!ret)
                        return n;
@@ -258,6 +337,11 @@ static struct attribute *interface_attrs[] = {
         * attribute, set in init function if applicable.
         */
        NULL,
+       /*
+        * This NULL is a placeholder for the processor_config
+        * attribute, set in init function if applicable.
+        */
+       NULL,
        NULL,
 };
 
@@ -463,17 +547,24 @@ static int hv_gpci_cpu_hotplug_init(void)
                          ppc_hv_gpci_cpu_offline);
 }
 
-static void add_sysinfo_interface_files(void)
+static struct device_attribute *sysinfo_device_attr_create(int
+               sysinfo_interface_group_index, u32 req)
 {
        struct device_attribute *attr = NULL;
        unsigned long ret;
        struct hv_gpci_request_buffer *arg;
 
-       /* Check for counter request type PROCESSOR_BUS_TOPOLOGY support */
+       if (sysinfo_interface_group_index < INTERFACE_PROCESSOR_BUS_TOPOLOGY_ATTR ||
+                       sysinfo_interface_group_index >= INTERFACE_NULL_ATTR) {
+               pr_info("Wrong interface group index for system information\n");
+               return NULL;
+       }
+
+       /* Check for given counter request value support */
        arg = (void *)get_cpu_var(hv_gpci_reqb);
        memset(arg, 0, HGPCI_REQ_BUFFER_SIZE);
 
-       arg->params.counter_request = cpu_to_be32(PROCESSOR_BUS_TOPOLOGY);
+       arg->params.counter_request = cpu_to_be32(req);
 
        ret = plpar_hcall_norets(H_GET_PERF_COUNTER_INFO,
                        virt_to_phys(arg), HGPCI_REQ_BUFFER_SIZE);
@@ -481,21 +572,68 @@ static void add_sysinfo_interface_files(void)
        put_cpu_var(hv_gpci_reqb);
 
        /*
-        * Add processor_bus_topology attribute in the interface_attrs
+        * Add given counter request value attribute in the interface_attrs
         * attribute array, only for valid return types.
         */
        if (!ret || ret == H_AUTHORITY || ret == H_PARAMETER) {
                attr = kzalloc(sizeof(*attr), GFP_KERNEL);
                if (!attr)
-                       return;
+                       return NULL;
 
                sysfs_attr_init(&attr->attr);
-               attr->attr.name = "processor_bus_topology";
                attr->attr.mode = 0444;
-               attr->show = processor_bus_topology_show;
-               interface_attrs[INTERFACE_PROCESSOR_BUS_TOPOLOGY_ATTR] = &attr->attr;
+
+               switch (sysinfo_interface_group_index) {
+               case INTERFACE_PROCESSOR_BUS_TOPOLOGY_ATTR:
+                       attr->attr.name = "processor_bus_topology";
+                       attr->show = processor_bus_topology_show;
+               break;
+               case INTERFACE_PROCESSOR_CONFIG_ATTR:
+                       attr->attr.name = "processor_config";
+                       attr->show = processor_config_show;
+               break;
+               }
        } else
                pr_devel("hcall failed, with error: 0x%lx\n", ret);
+
+       return attr;
+}
+
+static void add_sysinfo_interface_files(void)
+{
+       int sysfs_count;
+       struct device_attribute *attr[INTERFACE_NULL_ATTR - INTERFACE_PROCESSOR_BUS_TOPOLOGY_ATTR];
+       int i;
+
+       sysfs_count = INTERFACE_NULL_ATTR - INTERFACE_PROCESSOR_BUS_TOPOLOGY_ATTR;
+
+       /* Get device attribute for a given counter request value */
+       for (i = 0; i < sysfs_count; i++) {
+               attr[i] = sysinfo_device_attr_create(i + INTERFACE_PROCESSOR_BUS_TOPOLOGY_ATTR,
+                               sysinfo_counter_request[i]);
+
+               if (!attr[i])
+                       goto out;
+       }
+
+       /* Add sysinfo interface attributes in the interface_attrs attribute array */
+       for (i = 0; i < sysfs_count; i++)
+               interface_attrs[i + INTERFACE_PROCESSOR_BUS_TOPOLOGY_ATTR] = &attr[i]->attr;
+
+       return;
+
+out:
+       /*
+        * The sysinfo interface attributes will be added, only if hcall passed for
+        * all the counter request values. Free the device attribute array incase
+        * of any hcall failure.
+        */
+       if (i > 0) {
+               while (i >= 0) {
+                       kfree(attr[i]);
+                       i--;
+               }
+       }
 }
 
 static int hv_gpci_init(void)