[PATCH v1 26/31] x86/resctrl: Describe resctrl's bitmap size assumptions

James Morse
2024-03-21T16:52:54Z

resctrl operates on configuration bitmaps and a bitmap of allocated
CLOSID, both are stored in a u32.

MPAM supports configuration/portion bitmaps and PARTIDs larger
than will fit in a u32.

Add some preprocessor values that make it clear why MPAM clamps
some of these values. This will make it easier to find code related
to these values if this resctrl behaviour ever changes.

Signed-off-by: James Morse <james.morse@arm.com>
---
include/linux/resctrl.h | 11 +++++++++++
1 file changed, 11 insertions(+)

diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index 84420253dc05..f463fb949677 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -26,6 +26,17 @@ int proc_resctrl_show(struct seq_file *m,
/* max value for struct rdt_domain's mbps_val */
#define MBA_MAX_MBPS U32_MAX

+/*
+ * Resctrl uses a u32 as a closid bitmap. The maximum closid is 32.
+ */
+#define RESCTRL_MAX_CLOSID 32
+
+/*
+ * Resctrl uses u32 to hold the user-space config. The maximum bitmap size is
+ * 32.
+ */
+#define RESCTRL_MAX_CBM 32
+
/**
* struct pseudo_lock_region - pseudo-lock region information
* @s: Resctrl schema for the resource to which this
--
2.39.2