[PATCH v5 3/4] x86/resctrl: Add sparse_masks file in info

From: Maciej Wieczor-Retman
Date: Tue Oct 10 2023 - 06:43:30 EST


From: Fenghua Yu <fenghua.yu@xxxxxxxxx>

Add the interface in resctrl FS to show if sparse cache allocation
bit masks are supported on the platform. Reading the file returns
either a "1" if non-contiguous 1s are supported and "0" otherwise.
The file path is /sys/fs/resctrl/info/{resource}/sparse_masks, where
{resource} can be either "L2" or "L3".

Signed-off-by: Fenghua Yu <fenghua.yu@xxxxxxxxx>
Signed-off-by: Maciej Wieczor-Retman <maciej.wieczor-retman@xxxxxxxxx>
Tested-by: Peter Newman <peternewman@xxxxxxxxxx>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
Reviewed-by: Peter Newman <peternewman@xxxxxxxxxx>
Reviewed-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>
Reviewed-by: Babu Moger <babu.moger@xxxxxxx>
---
Changelog v5:
- Add Babu's reviewed-by tag.

Changelog v4:
- Add Ilpo's reviewed-by tag.
- Add Reinette's reviewed-by tag.

Changelog v3:
- Add Peter's tested-by and reviewed-by tags.
- Reword patch message slightly. (Reinette)

Changelog v2:
- Change bitmap naming convention to bit mask. (Reinette)
- Change file name to "sparse_masks". (Reinette)

arch/x86/kernel/cpu/resctrl/rdtgroup.c | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)

diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 725344048f85..945801898a4d 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -895,6 +895,17 @@ static int rdt_shareable_bits_show(struct kernfs_open_file *of,
return 0;
}

+static int rdt_has_sparse_bitmasks_show(struct kernfs_open_file *of,
+ struct seq_file *seq, void *v)
+{
+ struct resctrl_schema *s = of->kn->parent->priv;
+ struct rdt_resource *r = s->res;
+
+ seq_printf(seq, "%u\n", r->cache.arch_has_sparse_bitmasks);
+
+ return 0;
+}
+
/**
* rdt_bit_usage_show - Display current usage of resources
*
@@ -1839,6 +1850,13 @@ static struct rftype res_common_files[] = {
.seq_show = rdtgroup_size_show,
.fflags = RF_CTRL_BASE,
},
+ {
+ .name = "sparse_masks",
+ .mode = 0444,
+ .kf_ops = &rdtgroup_kf_single_ops,
+ .seq_show = rdt_has_sparse_bitmasks_show,
+ .fflags = RF_CTRL_INFO | RFTYPE_RES_CACHE,
+ },

};

--
2.42.0