[PATCH v3 01/10] powerpc/hv_gpci: Add sysfs file inside hv_gpci device to show processor bus topology information
Kajol Jain
kjain at linux.ibm.com
Wed Jul 19 16:12:22 AEST 2023
The hcall H_GET_PERF_COUNTER_INFO with counter request value as
PROCESSOR_BUS_TOPOLOGY(0XD0), can be used to get the system
topology information. To expose the system topology information,
patch adds sysfs file called "processor_bus_topology" to the
"/sys/devices/hv_gpci/interface/" of hv_gpci pmu driver.
Add macro for PROCESSOR_BUS_TOPOLOGY counter request value
in hv-gpci.c file. Also add a new function called
"systeminfo_gpci_request", to make the H_GET_PERF_COUNTER_INFO hcall
with added macro and populates the output buffer.
The processor_bus_topology sysfs file is only available for power10
and above platforms. Add a new function called
"add_sysinfo_interface_files", which will add processor_bus_topology
attribute in the interface_attrs array, only for power10 and
above platforms.
Also add macro INTERFACE_PROCESSOR_BUS_TOPOLOGY_ATTR in hv-gpci.c
file, which points to the index of NULL placefolder, for
processor_bus_topology attribute.
Signed-off-by: Kajol Jain <kjain at linux.ibm.com>
---
arch/powerpc/perf/hv-gpci.c | 184 +++++++++++++++++++++++++++++++++++-
1 file changed, 182 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/perf/hv-gpci.c b/arch/powerpc/perf/hv-gpci.c
index 7ff8ff3509f5..225f148f75fd 100644
--- a/arch/powerpc/perf/hv-gpci.c
+++ b/arch/powerpc/perf/hv-gpci.c
@@ -102,6 +102,141 @@ 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
+
+static DEFINE_PER_CPU(char, hv_gpci_reqb[HGPCI_REQ_BUFFER_SIZE]) __aligned(sizeof(uint64_t));
+
+static unsigned long systeminfo_gpci_request(u32 req, u32 starting_index,
+ u16 secondary_index, char *buf,
+ size_t *n, struct hv_gpci_request_buffer *arg)
+{
+ unsigned long ret;
+ size_t i, j;
+
+ arg->params.counter_request = cpu_to_be32(req);
+ arg->params.starting_index = cpu_to_be32(starting_index);
+ arg->params.secondary_index = cpu_to_be16(secondary_index);
+
+ ret = plpar_hcall_norets(H_GET_PERF_COUNTER_INFO,
+ virt_to_phys(arg), HGPCI_REQ_BUFFER_SIZE);
+
+ /*
+ * ret value as 'H_PARAMETER' corresponds to 'GEN_BUF_TOO_SMALL',
+ * which means that the current buffer size cannot accommodate
+ * all the information and a partial buffer returned.
+ * hcall fails incase of ret value other than H_SUCCESS or H_PARAMETER.
+ *
+ * ret value as H_AUTHORITY implies that partition is not permitted to retrieve
+ * performance information, and required to set
+ * "Enable Performance Information Collection" option.
+ */
+ if (ret == H_AUTHORITY)
+ return -EPERM;
+
+ /*
+ * hcall can fail with other possible ret value like H_PRIVILEGE/H_HARDWARE
+ * because of invalid buffer-length/address or due to some hardware
+ * error.
+ */
+ if (ret && (ret != H_PARAMETER))
+ return -EIO;
+
+ /*
+ * hcall H_GET_PERF_COUNTER_INFO populates the 'returned_values'
+ * to show the total number of counter_value array elements
+ * returned via hcall.
+ * hcall also populates 'cv_element_size' corresponds to individual
+ * counter_value array element size. Below loop go through all
+ * counter_value array elements as per their size and add it to
+ * the output buffer.
+ */
+ for (i = 0; i < be16_to_cpu(arg->params.returned_values); i++) {
+ j = i * be16_to_cpu(arg->params.cv_element_size);
+
+ for (; j < (i + 1) * be16_to_cpu(arg->params.cv_element_size); j++)
+ *n += sprintf(buf + *n, "%02x", (u8)arg->bytes[j]);
+ *n += sprintf(buf + *n, "\n");
+ }
+
+ if (*n >= PAGE_SIZE) {
+ pr_info("System information exceeds PAGE_SIZE\n");
+ return -EFBIG;
+ }
+
+ return ret;
+}
+
+static ssize_t processor_bus_topology_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 0xD0 corresponds to request
+ * type 'Processor_bus_topology', to retrieve
+ * the system topology information.
+ * starting_index value implies the starting hardware
+ * chip id.
+ */
+ ret = systeminfo_gpci_request(PROCESSOR_BUS_TOPOLOGY, 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 make 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 value is part of counter_value
+ * buffer elements, use the starting index value in the last
+ * element and add 1 to make 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(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 DEVICE_ATTR_RO(kernel_version);
static DEVICE_ATTR_RO(cpumask);
@@ -118,6 +253,11 @@ static struct attribute *interface_attrs[] = {
&hv_caps_attr_expanded.attr,
&hv_caps_attr_lab.attr,
&hv_caps_attr_collect_privileged.attr,
+ /*
+ * This NULL is a placeholder for the processor_bus_topology
+ * attribute, set in init function if applicable.
+ */
+ NULL,
NULL,
};
@@ -143,8 +283,6 @@ static const struct attribute_group *attr_groups[] = {
NULL,
};
-static DEFINE_PER_CPU(char, hv_gpci_reqb[HGPCI_REQ_BUFFER_SIZE]) __aligned(sizeof(uint64_t));
-
static unsigned long single_gpci_request(u32 req, u32 starting_index,
u16 secondary_index, u8 version_in, u32 offset, u8 length,
u64 *value)
@@ -325,6 +463,44 @@ static int hv_gpci_cpu_hotplug_init(void)
ppc_hv_gpci_cpu_offline);
}
+static void add_sysinfo_interface_files(void)
+{
+ struct device_attribute *attr = NULL;
+ unsigned long ret;
+ struct hv_gpci_request_buffer *arg;
+
+ /* Check for counter request type PROCESSOR_BUS_TOPOLOGY 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);
+
+ ret = plpar_hcall_norets(H_GET_PERF_COUNTER_INFO,
+ virt_to_phys(arg), HGPCI_REQ_BUFFER_SIZE);
+
+ put_cpu_var(hv_gpci_reqb);
+
+ /*
+ * Add processor_bus_topology 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) {
+ pr_info("Memory allocation failed for sysinfo interface files\n");
+ return;
+ }
+
+ sysfs_attr_init(&attr->attr);
+ attr->attr.name = "processor_bug_topology";
+ attr->attr.mode = 0444;
+ attr->show = processor_bus_topology_show;
+ interface_attrs[INTERFACE_PROCESSOR_BUS_TOPOLOGY_ATTR] = &attr->attr;
+ } else
+ pr_devel("hcall failed, with error: 0x%lx\n", ret);
+}
+
static int hv_gpci_init(void)
{
int r;
@@ -388,6 +564,10 @@ static int hv_gpci_init(void)
if (r)
return r;
+ /* sysinfo interface files are only available for power10 and above platforms */
+ if (PVR_VER(mfspr(SPRN_PVR)) >= PVR_POWER10)
+ add_sysinfo_interface_files();
+
return 0;
}
--
2.39.3
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