FVP: Remove GIC initialisation from secondary core cold boot

During the secondary cores' cold boot path, the cores initialise the GIC
CPU interface. However this is a redundant action since 1) the cores are
powered down immediately after that, 2) the GIC CPU interface is
initialised from scratch when the secondary cores are powered up again
later.

Moreover, this part of code was introducing a bug. In a GICv3 system,
the GIC's CPU interface system registers must not be written without the
core being marked as "awake" in the redistributor. However, this
sequence was performing such accesses and this would cause those cores
to hang. The hang was caused by the DSB instruction that would never
complete because of the GIC not recognising those writes.

For the two aforementioned reasons, the entire part of the GIC CPU
interface initialisation is removed.

Change-Id: I6c33a1edda69dd5b6add16a27390a70731b5532a
Signed-off-by: John Tsichritzis <[email protected]>

diff --git a/plat/arm/board/fvp/aarch64/fvp_helpers.S b/plat/arm/board/fvp/aarch64/fvp_helpers.S
index 09f19f6c351eaedece2937913aafa64b7f3d1bd9..8efc2386cfd943bc19add56b90d2fd5972e04256 100644 (file)
--- a/plat/arm/board/fvp/aarch64/fvp_helpers.S
+++ b/plat/arm/board/fvp/aarch64/fvp_helpers.S
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2013-2017, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2013-2019, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -16,14 +16,6 @@
        .globl  plat_is_my_cpu_primary
        .globl  plat_arm_calc_core_pos
 
-       .macro  fvp_choose_gicmmap  param1, param2, x_tmp, w_tmp, res
-       mov_imm \x_tmp, V2M_SYSREGS_BASE + V2M_SYS_ID
-       ldr     \w_tmp, [\x_tmp]
-       ubfx    \w_tmp, \w_tmp, #V2M_SYS_ID_BLD_SHIFT, #V2M_SYS_ID_BLD_LENGTH
-       cmp     \w_tmp, #BLD_GIC_VE_MMAP
-       csel    \res, \param1, \param2, eq
-       .endm
-
        /* -----------------------------------------------------
         * void plat_secondary_cold_boot_setup (void);
         *
@@ -49,35 +41,6 @@ func plat_secondary_cold_boot_setup
        mov_imm x1, PWRC_BASE
        str     w0, [x1, #PPOFFR_OFF]
 
-       /* ---------------------------------------------
-        * Disable GIC bypass as well
-        * ---------------------------------------------
-        */
-       /* Check for GICv3 system register access */
-       mrs     x0, id_aa64pfr0_el1
-       ubfx    x0, x0, #ID_AA64PFR0_GIC_SHIFT, #ID_AA64PFR0_GIC_WIDTH
-       cmp     x0, #1
-       b.ne    gicv2_bypass_disable
-
-       /* Check for SRE enable */
-       mrs     x1, ICC_SRE_EL3
-       tst     x1, #ICC_SRE_SRE_BIT
-       b.eq    gicv2_bypass_disable
-
-       mrs     x2, ICC_SRE_EL3
-       orr     x2, x2, #(ICC_SRE_DIB_BIT | ICC_SRE_DFB_BIT)
-       msr     ICC_SRE_EL3, x2
-       b       secondary_cold_boot_wait
-
-gicv2_bypass_disable:
-       mov_imm x0, VE_GICC_BASE
-       mov_imm x1, BASE_GICC_BASE
-       fvp_choose_gicmmap      x0, x1, x2, w2, x1
-       mov     w0, #(IRQ_BYP_DIS_GRP1 | FIQ_BYP_DIS_GRP1)
-       orr     w0, w0, #(IRQ_BYP_DIS_GRP0 | FIQ_BYP_DIS_GRP0)
-       str     w0, [x1, #GICC_CTLR]
-
-secondary_cold_boot_wait:
        /* ---------------------------------------------
         * There is no sane reason to come out of this
         * wfi so panic if we do. This cpu will be pow-