[PATCH v2 07/10] powerpc/hv_gpci: Add sysfs file inside hv_gpci device to show affinity domain via domain information

From: Kajol Jain
Date: Mon Jul 10 2023 - 05:28:52 EST


The hcall H_GET_PERF_COUNTER_INFO with counter request value as
AFFINITY_DOMAIN_INFORMATION_BY_DOMAIN(0XB0), can be used to get
the system affinity domain via domain information. To expose the system
affinity domain via domain information, patch adds sysfs file called
"affinity_domain_via_domain" to the "/sys/devices/hv_gpci/interface/"
of hv_gpci pmu driver.

Add new entry for AFFINITY_DOMAIN_VIA_DOM in sysinfo_counter_request
array, which points to the counter request value
"affinity_domain_via_domain" in hv-gpci.c file.

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

Signed-off-by: Kajol Jain <kjain@xxxxxxxxxxxxx>
---
arch/powerpc/perf/hv-gpci.c | 80 ++++++++++++++++++++++++++++++++++++-
1 file changed, 79 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/perf/hv-gpci.c b/arch/powerpc/perf/hv-gpci.c
index 68502cb18262..326b758df7c8 100644
--- a/arch/powerpc/perf/hv-gpci.c
+++ b/arch/powerpc/perf/hv-gpci.c
@@ -106,19 +106,22 @@ static ssize_t cpumask_show(struct device *dev,
#define INTERFACE_PROCESSOR_BUS_TOPOLOGY_ATTR 6
#define INTERFACE_PROCESSOR_CONFIG_ATTR 7
#define INTERFACE_AFFINITY_DOMAIN_VIA_VP_ATTR 8
-#define INTERFACE_NULL_ATTR 9
+#define INTERFACE_AFFINITY_DOMAIN_VIA_DOM_ATTR 9
+#define INTERFACE_NULL_ATTR 10

/* Counter request value to retrieve system information */
enum {
PROCESSOR_BUS_TOPOLOGY,
PROCESSOR_CONFIG,
AFFINITY_DOMAIN_VIA_VP, /* affinity domain via virtual processor */
+ AFFINITY_DOMAIN_VIA_DOM, /* affinity domain via domain */
};

static int sysinfo_counter_request[] = {
[PROCESSOR_BUS_TOPOLOGY] = 0xD0,
[PROCESSOR_CONFIG] = 0x90,
[AFFINITY_DOMAIN_VIA_VP] = 0xA0,
+ [AFFINITY_DOMAIN_VIA_DOM] = 0xB0,
};

static DEFINE_PER_CPU(char, hv_gpci_reqb[HGPCI_REQ_BUFFER_SIZE]) __aligned(sizeof(uint64_t));
@@ -389,6 +392,72 @@ static ssize_t affinity_domain_via_virtual_processor_show(struct device *dev,
return ret;
}

+static ssize_t affinity_domain_via_domain_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 0xB0 corresponds to request
+ * type 'Affinity_domain_information_by_domain',
+ * 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_DOM],
+ 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 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 + 1] +
+ (arg->bytes[last_element] << 8) + 1;
+
+ memset(arg, 0, HGPCI_REQ_BUFFER_SIZE);
+
+ ret = systeminfo_gpci_request(sysinfo_counter_request[AFFINITY_DOMAIN_VIA_DOM],
+ 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);

@@ -420,6 +489,11 @@ static struct attribute *interface_attrs[] = {
* attribute, set in init function if applicable.
*/
NULL,
+ /*
+ * This NULL is a placeholder for the affinity_domain_via_domain
+ * attribute, set in init function if applicable.
+ */
+ NULL,
NULL,
};

@@ -677,6 +751,10 @@ static struct device_attribute *sysinfo_device_attr_create(int
attr->attr.name = "affinity_domain_via_virtual_processor";
attr->show = affinity_domain_via_virtual_processor_show;
break;
+ case INTERFACE_AFFINITY_DOMAIN_VIA_DOM_ATTR:
+ attr->attr.name = "affinity_domain_via_domain";
+ attr->show = affinity_domain_via_domain_show;
+ break;
}
} else
pr_devel("hcall failed, with error: 0x%lx\n", ret);
--
2.31.1