arm64: mte: CPU feature detection and initial sysreg configuration

Add the cpufeature and hwcap entries to detect the presence of MTE. Any
secondary CPU not supporting the feature, if detected on the boot CPU,
will be parked.

Add the minimum SCTLR_EL1 and HCR_EL2 bits for enabling MTE. The Normal
Tagged memory type is configured in MAIR_EL1 before the MMU is enabled
in order to avoid disrupting other CPUs in the CnP domain.

Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Co-developed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Suzuki K Poulose <Suzuki.Poulose@arm.com>

arch/arm64/mm/proc.S

@@ -18,6 +18,7 @@
 #include <asm/cpufeature.h>
 #include <asm/alternative.h>
 #include <asm/smp.h>
+#include <asm/sysreg.h>
 
 #ifdef CONFIG_ARM64_64K_PAGES
 #define TCR_TG_FLAGS	TCR_TG0_64K | TCR_TG1_64K
@@ -425,6 +426,29 @@ SYM_FUNC_START(__cpu_setup)
 	 * Memory region attributes
 	 */
 	mov_q	x5, MAIR_EL1_SET
+#ifdef CONFIG_ARM64_MTE
+	/*
+	 * Update MAIR_EL1, GCR_EL1 and TFSR*_EL1 if MTE is supported
+	 * (ID_AA64PFR1_EL1[11:8] > 1).
+	 */
+	mrs	x10, ID_AA64PFR1_EL1
+	ubfx	x10, x10, #ID_AA64PFR1_MTE_SHIFT, #4
+	cmp	x10, #ID_AA64PFR1_MTE
+	b.lt	1f
+
+	/* Normal Tagged memory type at the corresponding MAIR index */
+	mov	x10, #MAIR_ATTR_NORMAL_TAGGED
+	bfi	x5, x10, #(8 *  MT_NORMAL_TAGGED), #8
+
+	/* initialize GCR_EL1: all non-zero tags excluded by default */
+	mov	x10, #(SYS_GCR_EL1_RRND | SYS_GCR_EL1_EXCL_MASK)
+	msr_s	SYS_GCR_EL1, x10
+
+	/* clear any pending tag check faults in TFSR*_EL1 */
+	msr_s	SYS_TFSR_EL1, xzr
+	msr_s	SYS_TFSRE0_EL1, xzr
+1:
+#endif
 	msr	mair_el1, x5
 	/*
 	 * Set/prepare TCR and TTBR. We use 512GB (39-bit) address range for