arm64/cpufeature: Optionally disable MTE via command-line
MTE support needs to be optionally disabled in runtime
for HW issue workaround, FW development and some
evaluation works on system resource and performance.
This patch makes two changes:
(1) moves init of tag-allocation bits(ATA/ATA0) to
cpu_enable_mte() as not cached in TLB.
(2) allows ID_AA64PFR1_EL1.MTE to be overridden on
its shadow value by giving "arm64.nomte" on cmdline.
When the feature value is off, ATA and TCF will not set
and the related functionalities are accordingly suppressed.
Suggested-by: Catalin Marinas <catalin.marinas@arm.com>
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>
Link: https://lore.kernel.org/r/20210803070824.7586-2-yee.lee@mediatek.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 0ead8bf..51e6bf4 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -1843,6 +1843,9 @@ static void bti_enable(const struct arm64_cpu_capabilities *__unused)
#ifdef CONFIG_ARM64_MTE
static void cpu_enable_mte(struct arm64_cpu_capabilities const *cap)
{
+ sysreg_clear_set(sctlr_el1, 0, SCTLR_ELx_ATA | SCTLR_EL1_ATA0);
+ isb();
+
/*
* Clear the tags in the zero page. This needs to be done via the
* linear map which has the Tagged attribute.