xen: refactor Xen hypervisor Kconfig options

Xen-related Kconfig options were highly dependand on BOARD/SOC xenvm.
It is not correct because Xen support may be used on any board and SoC.

So, Kconfig structure was refactored, now CONFIG_XEN is located in
arch/ directory (same as in Linux kernel) and can be selected for
any Cortex-A arm64 setup (no other platforms are currently supported).

Also remove confusion in Domain 0 naming: Domain-0, initial domain,
Dom0, privileged domain etc. Now all options related to Xen Domain 0
will be controlled by CONFIG_XEN_DOM0.

Signed-off-by: Dmytro Firsov <dmytro_firsov@epam.com>

arch/arm64/core/CMakeLists.txt

@@ -54,4 +54,4 @@ if(CMAKE_C_COMPILER_ID STREQUAL "GNU")
   zephyr_cc_option(-moverride=tune=no_ldp_stp_qregs)
 endif()
 
-add_subdirectory_ifdef(CONFIG_SOC_XENVM xen)
+add_subdirectory_ifdef(CONFIG_XEN xen)

arch/arm64/core/Kconfig

@@ -197,6 +197,8 @@ config ARMV8_A
 	  so that it can support some features included in the AArch64 state.
 	  It supports the T32 and A32 instruction sets.
 
+rsource "xen/Kconfig"
+
 endif # CPU_CORTEX_A
 
 if CPU_AARCH64_CORTEX_R

arch/arm64/core/xen/Kconfig

@@ -0,0 +1,20 @@
+# Xen hypervisor configuration options
+
+# Copyright (c) 2023 EPAM Systems
+# SPDX-License-Identifier: Apache-2.0
+
+config XEN
+	bool
+	default y
+	depends on ARMV8_A
+	depends on DT_HAS_XEN_XEN_ENABLED
+	help
+	  Enables support of Xen hypervisor on arm64 platform. Get enabled
+	  when board device tree contains "hypervisor" node with "xen,xen"
+	  compatible enabled.
+
+config XEN_DOM0
+	bool "Zephyr as Xen Domain 0"
+	depends on XEN
+	help
+	  Built binary will be used as Xen privileged domain (Domain 0).

drivers/CMakeLists.txt

@@ -15,7 +15,7 @@ add_subdirectory(usb_c)
 add_subdirectory_ifdef(CONFIG_ADC adc)
 add_subdirectory_ifdef(CONFIG_AUDIO audio)
 add_subdirectory_ifdef(CONFIG_BBRAM bbram)
-add_subdirectory_ifdef(CONFIG_BOARD_XENVM xen)
+add_subdirectory_ifdef(CONFIG_XEN xen)
 add_subdirectory_ifdef(CONFIG_BT_DRIVERS bluetooth)
 add_subdirectory_ifdef(CONFIG_CACHE_MANAGEMENT cache)
 add_subdirectory_ifdef(CONFIG_CAN can)

drivers/serial/Kconfig.xen

@@ -1,6 +1,6 @@
 # Xen hypervisor console via UART setup
 #
-# Copyright (c) 2021 EPAM Systems
+# Copyright (c) 2021-2023 EPAM Systems
 # SPDX-License-Identifier: Apache-2.0
 #
 
@@ -10,7 +10,7 @@ config UART_XEN_HVC
 	depends on DT_HAS_XEN_HVC_UART_ENABLED
 	select SERIAL_HAS_DRIVER
 	select SERIAL_SUPPORT_INTERRUPT
-	depends on !XEN_INITIAL_DOMAIN
+	depends on XEN && !XEN_DOM0
 	help
 	  Enable Xen ring buffer based hypervisor console driver. Used
 	  for Zephyr as unprivileged domain.
@@ -18,8 +18,7 @@ config UART_XEN_HVC
 config UART_XEN_HVC_CONSOLEIO
 	bool "Xen hypervisor Dom0 console UART driver"
 	select SERIAL_HAS_DRIVER
-	depends on BOARD_XENVM
+	depends on XEN_DOM0
-	depends on XEN_INITIAL_DOMAIN
 	default y
 	help
 	  Enable Xen hypervisor console driver. Used for Zephyr as
@@ -35,7 +34,6 @@ config XEN_HVC_INIT_PRIORITY
 
 config XEN_EARLY_CONSOLEIO
 	bool "Early printk/stdout through console_io Xen interface"
-	depends on BOARD_XENVM
 	depends on UART_XEN_HVC
 	help
 	  Enable setting of console_io symbol hook for stdout and printk.

drivers/xen/Kconfig

@@ -1,7 +1,7 @@
 # SPDX-License-Identifier: Apache-2.0
-# Copyright (c) 2022 EPAM Systems
+# Copyright (c) 2022-2023 EPAM Systems
 
-if SOC_XENVM
+if XEN
 
 menu "Xen drivers"
 
@@ -22,4 +22,4 @@ config XEN_GRANT_TABLE_INIT_PRIORITY
 
 endmenu
 
-endif # SOC_XENVM
+endif # XEN

soc/arm64/xenvm/Kconfig.soc

@@ -6,9 +6,3 @@ config SOC_XENVM
 	select ARM64
 	select ARM_ARCH_TIMER if SYS_CLOCK_EXISTS
 	select CPU_CORTEX_A72
-
-config XEN_INITIAL_DOMAIN
-	bool "Zephyr as Xen Domain 0"
-	depends on SOC_XENVM
-	help
-	  Built binary will be used as Xen privileged domain.