Re: [PATCH v11 5/5] Documentation: document the preferred tag checking mode feature

Document the functionality added in the previous patches.

Link: https://linux-review.googlesource.com/id/I48217cc3e8b8da33abc08cbaddc11cf4360a1b86
Signed-off-by: Peter Collingbourne <redacted>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Will Deacon <will@kernel.org>
---
v10:
- document that setting the sysfs node may not take effect
  immediately
- unabbreviate month name

v9:
- add documentation for sysfs node under Documentation/ABI

 .../ABI/testing/sysfs-devices-system-cpu      | 18 +++++++
 .../arm64/memory-tagging-extension.rst        | 48 ++++++++++++++++---
 2 files changed, 59 insertions(+), 7 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu
index 160b10c029c0..5f87b146deb9 100644
--- a/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu

@@ -640,3 +640,21 @@ Description:	SPURR ticks for cpuX when it was idle.
 
 		This sysfs interface exposes the number of SPURR ticks
 		for cpuX when it was idle.
+
+What: 		/sys/devices/system/cpu/cpuX/mte_tcf_preferred
+Date:		July 2021
+Contact:	Linux ARM Kernel Mailing list <linux-arm-kernel@lists.infradead.org>
+Description:	Preferred MTE tag checking mode
+
+		When a user program specifies more than one MTE tag checking
+		mode, this sysfs node is used to specify which mode should
+		be preferred when running on that CPU. Possible values:
+
+		================  ==============================================
+		"sync"	  	  Prefer synchronous mode
+		"async"	  	  Prefer asynchronous mode
+		================  ==============================================
+
+		Changes to this sysfs node may not take effect immediately.