[PATCH v2 0/1] Add option to disable mte support

[PATCH v2 0/1] Add option to disable mte support

[yee.lee]

From: Yee Lee <yee.lee@mediatek.com>

For some case of low-end devices with limited resources,
an option to disable mte support is necessary.

This patch Adds an alias in id-reg override mechanism
to suppress the mte feature via passing a param.

=== Test ===
QEMU5.2 + mte
passed "arm64.nomte" in cmdline
boot log:
..(skip)
[    0.000000] CPU features: SYS_ID_AA64PFR1_EL1[11:8]: forced to 0

Changed since v2:
 - Use id-reg override machanism to suppress feature. 

Yee Lee (1):
  arm64/cpufeature: Add arm64.nomte to override id-reg

 arch/arm64/kernel/idreg-override.c | 2 ++
 1 file changed, 2 insertions(+)

-- 
2.18.0

[PATCH v2 1/1] arm64/cpufeature: Add arm64.nomte to override id-reg

[yee.lee]

From: Yee Lee <yee.lee@mediatek.com>

Add an alias, "arm64.nomte", to override id-reg and
suppress mte feature.

Suggested-by: Marc Zyngier <maz@kernel.org>
Suggested-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Yee Lee <yee.lee@mediatek.com>
---
 arch/arm64/kernel/idreg-override.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/arm64/kernel/idreg-override.c b/arch/arm64/kernel/idreg-override.c
index 53a381a7f65d..d8e606fe3c21 100644
--- a/arch/arm64/kernel/idreg-override.c
+++ b/arch/arm64/kernel/idreg-override.c
@@ -54,6 +54,7 @@ static const struct ftr_set_desc pfr1 __initconst = {
 	.override	= &id_aa64pfr1_override,
 	.fields		= {
 	        { "bt", ID_AA64PFR1_BT_SHIFT },
+		{ "mte", ID_AA64PFR1_MTE_SHIFT},
 		{}
 	},
 };
@@ -100,6 +101,7 @@ static const struct {
 	{ "arm64.nopauth",
 	  "id_aa64isar1.gpi=0 id_aa64isar1.gpa=0 "
 	  "id_aa64isar1.api=0 id_aa64isar1.apa=0"	   },
+	{ "arm64.nomte",		"id_aa64pfr1.mte=0" },
 	{ "nokaslr",			"kaslr.disabled=1" },
 };
 
-- 
2.18.0