fix(plat/marvell/a3k): disable HANDLE_EA_EL3_FIRST by default

It was enabled in commit 3c7dcdac5c ("marvell/a3700: Prevent SError
accessing PCIe link while it is down") with a workaround for a bug found
in U-Boot and Linux kernel driver pci-aardvark.c (PCIe controller driver
for Armada 37xx SoC) which results in SError interrupt caused by AXI
SLVERR on external access (syndrome 0xbf000002) and immediate kernel
panic.

Now when proper patches are in both U-Boot and Linux kernel projects,
this workaround in TF-A should not have to be enabled by default
anymore as it has unwanted side effects like propagating all external
aborts, including non-fatal/correctable into EL3 and making them as
fatal which cause immediate abort.

Add documentation for HANDLE_EA_EL3_FIRST build option into Marvell
Armada build section.

Signed-off-by: Pali Rohár <pali@kernel.org>
Change-Id: Ic92b65bf9923505ab682830afb66c2f6cec70491

docs/plat/marvell/armada/build.rst

@@ -139,6 +139,29 @@ A7K/8K/CN913x specific build options:
 
 Armada37x0 specific build options:
 
+- HANDLE_EA_EL3_FIRST
+
+        When ``HANDLE_EA_EL3_FIRST=1``, External Aborts and SError Interrupts will be always trapped
+        in TF-A. TF-A in this case enables dirty hack / workaround for a bug found in U-Boot and
+        Linux kernel PCIe controller driver pci-aardvark.c, traps and then masks SError interrupt
+        caused by AXI SLVERR on external access (syndrome 0xbf000002).
+
+        Otherwise when ``HANDLE_EA_EL3_FIRST=0``, these exceptions will be trapped in the current
+        exception level (or in EL1 if the current exception level is EL0). So exceptions caused by
+        U-Boot will be trapped in U-Boot, exceptions caused by Linux kernel (or user applications)
+        will be trapped in Linux kernel.
+
+        Mentioned bug in pci-aardvark.c driver is fixed in U-Boot version v2021.07 and Linux kernel
+        version v5.13 (workarounded since Linux kernel version 5.9) and also backported in Linux
+        kernel stable releases since versions v5.12.13, v5.10.46, v5.4.128, v4.19.198, v4.14.240.
+
+        If target system has already patched version of U-Boot and Linux kernel then it is strongly
+        recommended to not enable this workaround as it disallows propagating of all External Aborts
+        to running Linux kernel and makes correctable errors as fatal aborts.
+
+        This option is now disabled by default. In past this option was enabled by default in
+        TF-A versions v2.2, v2.3, v2.4 and v2.5.
+
 - CM3_SYSTEM_RESET
 
         When ``CM3_SYSTEM_RESET=1``, the Cortex-M3 secure coprocessor will be used for system reset.

plat/marvell/armada/a3k/common/a3700_common.mk

@@ -13,7 +13,6 @@ PLAT_INCLUDE_BASE		:= $(MARVELL_PLAT_INCLUDE_BASE)/$(PLAT_FAMILY)
 PLAT_COMMON_BASE		:= $(PLAT_FAMILY_BASE)/common
 MARVELL_DRV_BASE		:= drivers/marvell
 MARVELL_COMMON_BASE		:= $(MARVELL_PLAT_BASE)/common
-HANDLE_EA_EL3_FIRST		:= 1
 
 include plat/marvell/marvell.mk
 
@@ -53,7 +52,6 @@ BL31_SOURCES		+=	lib/cpus/aarch64/cortex_a53.S		\
 				$(PLAT_COMMON_BASE)/dram_win.c		\
 				$(PLAT_COMMON_BASE)/io_addr_dec.c	\
 				$(PLAT_COMMON_BASE)/marvell_plat_config.c     \
-				$(PLAT_COMMON_BASE)/a3700_ea.c		\
 				$(PLAT_FAMILY_BASE)/$(PLAT)/plat_bl31_setup.c \
 				$(MARVELL_COMMON_BASE)/marvell_cci.c	\
 				$(MARVELL_COMMON_BASE)/marvell_ddr_info.c	\
@@ -63,6 +61,10 @@ BL31_SOURCES		+=	lib/cpus/aarch64/cortex_a53.S		\
 				$(PLAT_COMMON_BASE)/a3700_sip_svc.c	\
 				$(MARVELL_DRV)
 
+ifeq ($(HANDLE_EA_EL3_FIRST),1)
+BL31_SOURCES		+=	$(PLAT_COMMON_BASE)/a3700_ea.c
+endif
+
 ifeq ($(CM3_SYSTEM_RESET),1)
 BL31_SOURCES		+=	$(PLAT_COMMON_BASE)/cm3_system_reset.c
 endif

plat/marvell/armada/a3k/common/a3700_ea.c

@@ -24,6 +24,10 @@ static const char *get_el_str(unsigned int el)
 }
 #endif /* !ENABLE_BACKTRACE */
 
+/*
+ * This source file with custom plat_ea_handler function is compiled only when
+ * building TF-A with compile option HANDLE_EA_EL3_FIRST=1
+ */
 void plat_ea_handler(unsigned int ea_reason, uint64_t syndrome, void *cookie,
 		void *handle, uint64_t flags)
 {