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Message-ID: <176382649929.498.8411171126977024741.tip-bot2@tip-bot2>
Date: Sat, 22 Nov 2025 15:48:19 -0000
From: "tip-bot2 for Babu Moger" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Babu Moger <babu.moger@....com>, "Borislav Petkov (AMD)" <bp@...en8.de>,
Reinette Chatre <reinette.chatre@...el.com>, x86@...nel.org,
linux-kernel@...r.kernel.org
Subject: [tip: x86/cache] fs/resctrl: Update bit_usage to reflect io_alloc
The following commit has been merged into the x86/cache branch of tip:
Commit-ID: ac7de456a37f9b126eb53b89c2bb27d625dc5fd9
Gitweb: https://git.kernel.org/tip/ac7de456a37f9b126eb53b89c2bb27d625dc5fd9
Author: Babu Moger <babu.moger@....com>
AuthorDate: Wed, 12 Nov 2025 18:57:36 -06:00
Committer: Borislav Petkov (AMD) <bp@...en8.de>
CommitterDate: Sat, 22 Nov 2025 14:30:34 +01:00
fs/resctrl: Update bit_usage to reflect io_alloc
The "shareable_bits" and "bit_usage" resctrl files associated with cache
resources give insight into how instances of a cache is used.
Update the annotated capacity bitmasks displayed by "bit_usage" to include the
cache portions allocated for I/O via the "io_alloc" feature. "shareable_bits"
is a global bitmask of shareable cache with I/O and can thus not present the
per-domain I/O allocations possible with the "io_alloc" feature. Revise the
"shareable_bits" documentation to direct users to "bit_usage" for accurate
cache usage information.
Signed-off-by: Babu Moger <babu.moger@....com>
Signed-off-by: Borislav Petkov (AMD) <bp@...en8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@...el.com>
Link: https://patch.msgid.link/e02a0d424129fd7f3e45822a559b1c614ae4652a.1762995456.git.babu.moger@amd.com
---
Documentation/filesystems/resctrl.rst | 35 +++++++++++++++-----------
fs/resctrl/ctrlmondata.c | 2 +-
fs/resctrl/internal.h | 1 +-
fs/resctrl/rdtgroup.c | 21 ++++++++++++++--
4 files changed, 42 insertions(+), 17 deletions(-)
diff --git a/Documentation/filesystems/resctrl.rst b/Documentation/filesystems/resctrl.rst
index bbc4b6c..8c8ce67 100644
--- a/Documentation/filesystems/resctrl.rst
+++ b/Documentation/filesystems/resctrl.rst
@@ -96,12 +96,19 @@ related to allocation:
must be set when writing a mask.
"shareable_bits":
- Bitmask of shareable resource with other executing
- entities (e.g. I/O). User can use this when
- setting up exclusive cache partitions. Note that
- some platforms support devices that have their
- own settings for cache use which can over-ride
- these bits.
+ Bitmask of shareable resource with other executing entities
+ (e.g. I/O). Applies to all instances of this resource. User
+ can use this when setting up exclusive cache partitions.
+ Note that some platforms support devices that have their
+ own settings for cache use which can over-ride these bits.
+
+ When "io_alloc" is enabled, a portion of each cache instance can
+ be configured for shared use between hardware and software.
+ "bit_usage" should be used to see which portions of each cache
+ instance is configured for hardware use via "io_alloc" feature
+ because every cache instance can have its "io_alloc" bitmask
+ configured independently via "io_alloc_cbm".
+
"bit_usage":
Annotated capacity bitmasks showing how all
instances of the resource are used. The legend is:
@@ -115,16 +122,16 @@ related to allocation:
"H":
Corresponding region is used by hardware only
but available for software use. If a resource
- has bits set in "shareable_bits" but not all
- of these bits appear in the resource groups'
- schematas then the bits appearing in
- "shareable_bits" but no resource group will
- be marked as "H".
+ has bits set in "shareable_bits" or "io_alloc_cbm"
+ but not all of these bits appear in the resource
+ groups' schemata then the bits appearing in
+ "shareable_bits" or "io_alloc_cbm" but no
+ resource group will be marked as "H".
"X":
Corresponding region is available for sharing and
- used by hardware and software. These are the
- bits that appear in "shareable_bits" as
- well as a resource group's allocation.
+ used by hardware and software. These are the bits
+ that appear in "shareable_bits" or "io_alloc_cbm"
+ as well as a resource group's allocation.
"S":
Corresponding region is used by software
and available for sharing.
diff --git a/fs/resctrl/ctrlmondata.c b/fs/resctrl/ctrlmondata.c
index 332918f..b2d178d 100644
--- a/fs/resctrl/ctrlmondata.c
+++ b/fs/resctrl/ctrlmondata.c
@@ -750,7 +750,7 @@ out:
* resource. Note that if Code Data Prioritization (CDP) is enabled, the number
* of available CLOSIDs is reduced by half.
*/
-static u32 resctrl_io_alloc_closid(struct rdt_resource *r)
+u32 resctrl_io_alloc_closid(struct rdt_resource *r)
{
if (resctrl_arch_get_cdp_enabled(r->rid))
return resctrl_arch_get_num_closid(r) / 2 - 1;
diff --git a/fs/resctrl/internal.h b/fs/resctrl/internal.h
index e1eda74..bff4a54 100644
--- a/fs/resctrl/internal.h
+++ b/fs/resctrl/internal.h
@@ -442,6 +442,7 @@ int resctrl_io_alloc_cbm_show(struct kernfs_open_file *of, struct seq_file *seq,
void *v);
ssize_t resctrl_io_alloc_cbm_write(struct kernfs_open_file *of, char *buf,
size_t nbytes, loff_t off);
+u32 resctrl_io_alloc_closid(struct rdt_resource *r);
#ifdef CONFIG_RESCTRL_FS_PSEUDO_LOCK
int rdtgroup_locksetup_enter(struct rdtgroup *rdtgrp);
diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index 3614974..8e39dfd 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -1062,15 +1062,17 @@ static int rdt_bit_usage_show(struct kernfs_open_file *of,
cpus_read_lock();
mutex_lock(&rdtgroup_mutex);
- hw_shareable = r->cache.shareable_bits;
list_for_each_entry(dom, &r->ctrl_domains, hdr.list) {
if (sep)
seq_putc(seq, ';');
+ hw_shareable = r->cache.shareable_bits;
sw_shareable = 0;
exclusive = 0;
seq_printf(seq, "%d=", dom->hdr.id);
for (i = 0; i < closids_supported(); i++) {
- if (!closid_allocated(i))
+ if (!closid_allocated(i) ||
+ (resctrl_arch_get_io_alloc_enabled(r) &&
+ i == resctrl_io_alloc_closid(r)))
continue;
ctrl_val = resctrl_arch_get_config(r, dom, i,
s->conf_type);
@@ -1098,6 +1100,21 @@ static int rdt_bit_usage_show(struct kernfs_open_file *of,
break;
}
}
+
+ /*
+ * When the "io_alloc" feature is enabled, a portion of the cache
+ * is configured for shared use between hardware and software.
+ * Also, when CDP is enabled the CBMs of CDP_CODE and CDP_DATA
+ * resources are kept in sync. So, the CBMs for "io_alloc" can
+ * be accessed through either resource.
+ */
+ if (resctrl_arch_get_io_alloc_enabled(r)) {
+ ctrl_val = resctrl_arch_get_config(r, dom,
+ resctrl_io_alloc_closid(r),
+ s->conf_type);
+ hw_shareable |= ctrl_val;
+ }
+
for (i = r->cache.cbm_len - 1; i >= 0; i--) {
pseudo_locked = dom->plr ? dom->plr->cbm : 0;
hwb = test_bit(i, &hw_shareable);
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