Commit 22043a3c authored Oct 31, 2017 by Dave Martin Committed by Will Deacon Nov 03, 2017

arm64/sve: Low-level CPU setup



To enable the kernel to use SVE, SVE traps from EL1 to EL2 must be
disabled.  To take maximum advantage of the hardware, the full
available vector length also needs to be enabled for EL1 by
programming ZCR_EL2.LEN.  (The kernel will program ZCR_EL1.LEN as
required, but this cannot override the limit set by ZCR_EL2.)

This patch makes the appropriate changes to the EL2 early setup
code.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>

parent d0b8cd31

arch/arm64/kernel/head.S

+12 −1

Original line number	Diff line number	Diff line
		@@ -524,8 +524,19 @@ CPU_LE( movk x0, #0x30d0, lsl #16 ) // Clear EE and E0E on LE systems
		mov x0, #0x33ff
		msr cptr_el2, x0 // Disable copro. traps to EL2

		/* SVE register access */
		mrs x1, id_aa64pfr0_el1
		ubfx x1, x1, #ID_AA64PFR0_SVE_SHIFT, #4
		cbz x1, 7f

		bic x0, x0, #CPTR_EL2_TZ // Also disable SVE traps
		msr cptr_el2, x0 // Disable copro. traps to EL2
		isb
		mov x1, #ZCR_ELx_LEN_MASK // SVE: Enable full vector
		msr_s SYS_ZCR_EL2, x1 // length for EL1.

		/* Hypervisor stub */
		adr_l x0, __hyp_stub_vectors
		7: adr_l x0, __hyp_stub_vectors
		msr vbar_el2, x0

		/* spsr */