Commit 71f1c396 authored by Kajol Jain's avatar Kajol Jain Committed by Michael Ellerman
Browse files

powerpc/hv_gpci: Add sysfs file inside hv_gpci device to show processor bus topology information 



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.

Reviewed-by: default avatarAthira Rajeev <atrajeev@linux.vnet.ibm.com>
Signed-off-by: default avatarKajol Jain <kjain@linux.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230729073455.7918-2-kjain@linux.ibm.com
parent 58b6fed8

arch/powerpc/perf/hv-gpci.c

+179 −2
Original line number Diff line number Diff line
@@ -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 +463,41 @@ 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)

			return;



		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;

	} else

		pr_devel("hcall failed, with error: 0x%lx\n", ret);

}



static int hv_gpci_init(void)

{

	int r;
@@ -388,6 +561,10 @@ 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;

}