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powerpc/hv-gpci: Add sysfs files inside hv-gpci device to show cpumask

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Patch here adds a cpumask attr to hv_gpci pmu along with ABI documentation.

Primary use to expose the cpumask is for the perf tool which has the
capability to parse the driver sysfs folder and understand the
cpumask file. Having cpumask file will reduce the number of perf command
line parameters (will avoid "-C" option in the perf tool
command line). It can also notify the user which is
the current cpu used to retrieve the counter data.

command:# cat /sys/devices/hv_gpci/cpumask
0

Signed-off-by: Kajol Jain <kjain@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201003074943.338618-5-kjain@linux.ibm.com
This commit is contained in:
Kajol Jain 2020-10-03 13:19:43 +05:30 committed by Michael Ellerman
parent dcb5cdf60a
commit 09b791d955
2 changed files with 25 additions and 0 deletions
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7
Documentation/ABI/testing/sysfs-bus-event_source-devices-hv_gpci
View File

@ -72,3 +72,10 @@ Contact: Linux on PowerPC Developer List <linuxppc-dev@lists.ozlabs.org>
Description:
A number indicating the latest version of the gpci interface
that the kernel is aware of.
What: /sys/devices/hv_gpci/cpumask
Date: October 2020
Contact: Linux on PowerPC Developer List <linuxppc-dev@lists.ozlabs.org>
Description: read only
This sysfs file exposes the cpumask which is designated to make
HCALLs to retrieve hv-gpci pmu event counter data.

18
arch/powerpc/perf/hv-gpci.c
View File

@ -96,7 +96,15 @@ static ssize_t kernel_version_show(struct device *dev,
return sprintf(page, "0x%x\n", COUNTER_INFO_VERSION_CURRENT);
}
static ssize_t cpumask_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
return cpumap_print_to_pagebuf(true, buf, &hv_gpci_cpumask);
}
static DEVICE_ATTR_RO(kernel_version);
static DEVICE_ATTR_RO(cpumask);
HV_CAPS_ATTR(version, "0x%x\n");
HV_CAPS_ATTR(ga, "%d\n");
HV_CAPS_ATTR(expanded, "%d\n");
@ -113,6 +121,15 @@ static struct attribute *interface_attrs[] = {
NULL,
};
static struct attribute *cpumask_attrs[] = {
&dev_attr_cpumask.attr,
NULL,
};
static struct attribute_group cpumask_attr_group = {
.attrs = cpumask_attrs,
};
static struct attribute_group interface_group = {
.name = "interface",
.attrs = interface_attrs,
@ -122,6 +139,7 @@ static const struct attribute_group *attr_groups[] = {
&format_group,
&event_group,
&interface_group,
&cpumask_attr_group,
NULL,
};