[PATCH v5 04/16] fs/resctrl: Introduce kernel mode policy enum

[Babu Moger]

Kernel mode traffic can use different allocation and monitoring
associations than the originating user task. On x86, Privilege Level Zero
Association (PLZA) enables the kernel to switch to a different CLOSID/RMID
when entering kernel mode.

Architectures need a common way to name kernel modes before resctrl
can report what is active or what the platform supports.

Introduce enum resctrl_kernel_mode:
  - RESCTRL_INHERIT_USER: Kernel mode inherits allocation and monitoring
    from the user task.
  - RESCTRL_ASSIGN_GLOBAL_ENABLE_PER_CPU: Kernel mode may use allocation
    and/or monitoring associations that differ from the user task. On x86,
    CLOSID and RMID can be configured independently for kernel mode.

Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
---
v5: Collapse the two global-assign modes into a single
    RESCTRL_ASSIGN_GLOBAL_ENABLE_PER_CPU value. Update the changelog to
    match the enum names and descriptions in the code.

v4: Updated the changelog to be generic as possible.
    Moved the enum resctrl_kernel_mode to include/linux/resctrl.h.
    Updated the code comments to be generic.
    Removed resctrl_kmode_cfg from the code. This definition can be fs
    specific only and architectures dont need to know.
    Changed enum name to resctrl_kernel_mode from resctrl_kernel_modes.

v3: Removed resctrl_kmode definition.
    Changed the kernel mode definitions to enum resctrl_kernel_modes.
    Used BIT() to set/test the features.
    Added details to changelog.

v2: New patch to handle PLZA interfaces with /sys/fs/resctrl/info/ directory.
    https://lore.kernel.org/lkml/2ab556af-095b-422b-9396-f845c6fd0342@xxxxxxxxx/
---
 include/linux/resctrl.h | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index dd09c2ce9a0f..4245d1e65ccc 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -704,6 +704,31 @@ int resctrl_arch_io_alloc_enable(struct rdt_resource *r, bool enable);
  */
 bool resctrl_arch_get_io_alloc_enabled(struct rdt_resource *r);
 
+/**
+ * enum resctrl_kernel_mode - Kernel mode control and monitoring association.
+ *
+ * @RESCTRL_INHERIT_USER:
+ *     Kernel mode inherits both allocation and monitoring associations
+ *     from the user space task. On x86, kernel uses the same CLOSID and
+ *     RMID as the user-space task.
+ *
+ * @RESCTRL_ASSIGN_GLOBAL_ENABLE_PER_CPU:
+ *     Kernel mode may use allocation and monitoring associations that
+ *     differ from the user task. On x86, CLOSID and RMID are configured
+ *     independently; either or both may differ from user mode.
+ *
+ *     All online CPUs are included by default. A subset may be selected
+ *     through the resctrl group interface, and a CTRL_MON or MON group
+ *     may be associated with this mode.
+ */
+enum resctrl_kernel_mode {
+	RESCTRL_INHERIT_USER,
+	RESCTRL_ASSIGN_GLOBAL_ENABLE_PER_CPU,
+	RESCTRL_KMODE_LAST = RESCTRL_ASSIGN_GLOBAL_ENABLE_PER_CPU
+};
+
+#define RESCTRL_NUM_KERNEL_MODES (RESCTRL_KMODE_LAST + 1)
+
 extern unsigned int resctrl_rmid_realloc_threshold;
 extern unsigned int resctrl_rmid_realloc_limit;
 
-- 
2.43.0