Add support of Xen PV console via UART-like driver

CODEOWNERS

@@ -24,6 +24,7 @@
 /arch/arm/core/aarch32/cortex_a_r/        @MaureenHelm @galak @ioannisg @bbolen @stephanosio
 /arch/arm64/                              @carlocaione
 /arch/arm64/core/cortex_r/                @povergoing
+/arch/arm64/core/xen/                     @lorc @firscity
 /arch/common/                             @ioannisg @andyross
 /soc/arc/snps_*/                          @abrodkin @ruuddw @evgeniy-paltsev
 /soc/nios2/                               @nashif
@@ -60,7 +61,7 @@
 /soc/arm64/qemu_cortex_a53/               @carlocaione
 /soc/arm64/bcm_vk/                        @abhishek-brcm
 /soc/arm64/nxp_layerscape/                @JiafeiPan
-/soc/arm64/xenvm/                         @lorc
+/soc/arm64/xenvm/                         @lorc @firscity
 /soc/arm64/arm/                           @povergoing
 /soc/arm64/arm/fvp_aemv8a/                @carlocaione
 /submanifests/*                           @mbolivar-nordic
@@ -166,7 +167,7 @@
 /boards/arm64/qemu_cortex_a53/            @carlocaione
 /boards/arm64/bcm958402m2_a72/            @abhishek-brcm
 /boards/arm64/nxp_ls1046ardb/             @JiafeiPan
-/boards/arm64/xenvm/                      @lorc
+/boards/arm64/xenvm/                      @lorc @firscity
 /boards/arm64/fvp_baser_aemv8r/           @povergoing
 /boards/arm64/fvp_base_revc_2xaemv8a/     @carlocaione
 /boards/arm64/intel_socfpga_agilex_socdk/ @siclim @ngboonkhai
@@ -343,6 +344,8 @@
 /drivers/serial/serial_test.c             @str4t0m
 /drivers/serial/*esp32c3*                 @uLipe
 /drivers/serial/*esp32s2*                 @glaubermaroto
+/drivers/serial/Kconfig.xen               @lorc @firscity
+/drivers/serial/uart_hvc_xen.c            @lorc @firscity
 /drivers/disk/                            @jfischer-no
 /drivers/disk/sdmmc_sdhc.h                @JunYangNXP
 /drivers/disk/sdmmc_spi.c                 @JunYangNXP
@@ -389,6 +392,7 @@
 /drivers/wifi/eswifi/                     @loicpoulain @nandojve
 /drivers/wifi/winc1500/                   @kludentwo
 /drivers/virtualization/		  @tbursztyka
+/drivers/xen/                             @lorc @firscity
 /dts/arc/                                 @abrodkin @ruuddw @iriszzw @evgeniy-paltsev
 /dts/arm/acsip/                           @NorthernDean
 /dts/arm/atmel/sam4e*                     @nandojve

arch/arm64/core/CMakeLists.txt

@@ -30,3 +30,5 @@ if ((CONFIG_MP_NUM_CPUS GREATER 1) OR (CONFIG_SMP))
 endif ()
 
 zephyr_cc_option_ifdef(CONFIG_USERSPACE -mno-outline-atomics)
+
+add_subdirectory_ifdef(CONFIG_SOC_XENVM xen)

arch/arm64/core/xen/CMakeLists.txt

@@ -0,0 +1,10 @@
+# SPDX-License-Identifier: Apache-2.0
+# Copyright (c) 2021 EPAM Systems
+
+# Needed to separate definitions in common Xen headers
+zephyr_compile_options($<$<COMPILE_LANGUAGE:ASM>:-D__ASSEMBLY__>)
+
+# Xen interface version used in headers for correct definition
+zephyr_compile_options(-D__XEN_INTERFACE_VERSION__=0x00040e00)
+
+zephyr_library_sources(hypercall.S)

arch/arm64/core/xen/hypercall.S

@@ -0,0 +1,26 @@
+/*
+ * Copyright (c) 2021 EPAM Systems
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <toolchain.h>
+#include <linker/sections.h>
+#include <xen/public/arch-arm.h>
+#include <xen/public/xen.h>
+
+#define HYPERCALL(hypercall)			\
+GTEXT(HYPERVISOR_##hypercall);			\
+SECTION_FUNC(TEXT, HYPERVISOR_##hypercall)	\
+	mov x16, #__HYPERVISOR_##hypercall;	\
+	hvc XEN_HYPERCALL_TAG;			\
+	ret;
+
+_ASM_FILE_PROLOGUE
+
+HYPERCALL(console_io);
+HYPERCALL(grant_table_op);
+HYPERCALL(sched_op);
+HYPERCALL(event_channel_op);
+HYPERCALL(hvm_op);
+HYPERCALL(memory_op);

boards/arm64/xenvm/doc/index.rst

@@ -20,8 +20,6 @@ It provides minimal set of devices:
 
 * ARM Generic timer
 * GICv2
-* SBSA (subset of PL011) UART controller
-
 
 Hardware
 ********
@@ -35,8 +33,6 @@ The following hardware features are supported:
 +==============+=============+======================+
 | GIC          | virtualized | interrupt controller |
 +--------------+-------------+----------------------+
-| SBSA UART    | emulated    | serial port          |
-+--------------+-------------+----------------------+
 | ARM TIMER    | virtualized | system clock         |
 +--------------+-------------+----------------------+
 
@@ -57,13 +53,6 @@ boot log:
 
   (XEN) [    0.147541] Generic Timer IRQ: phys=30 hyp=26 virt=27 Freq: 8320 KHz
 
-Serial Port
------------
-
-This board configuration uses a single serial communication channel using SBSA
-UART. This is a minimal UART implementation provided by Xen. Xen PV Console is
-not supported at this moment.
-
 Interrupt Controller
 --------------------
 
@@ -88,13 +77,17 @@ configuration would not boot on your hardware. In this case you need to update
 configuration by altering device tree and Kconfig options. This will be covered
 in detail in next section.
 
-No Xen-specific features are supported at the moment. This includes:
+Most of Xen-specific features are not supported at the moment. This includes:
 
-* Xen Enlighten memory page
+* Xen Enlighten memory page (under development)
 * XenBus
-* Xen event channels
+* Xen event channels (under development)
 * Xen grant tables
-* Xen PV drivers (including PV console)
+* Xen PV drivers
+
+Now only following features are supported:
+* Xen PV console (UART-like driver with poll API, IRQ driven is under development)
+* Xen early console_io interface (mainly for debug purposes)
 
 Building and Running
 ********************
@@ -118,7 +111,6 @@ create guest configuration file :code:`zephyr.conf`. There is example:
    memory=16
    gic_version="v2"
    on_crash="preserve"
-   vuart="sbsa_uart"
 
 You need to upload both :code:`zephyr.bin` and :code:`zephyr.conf` to your Dom0
 and then you can run Zephyr by issuing
@@ -127,11 +119,17 @@ and then you can run Zephyr by issuing
 
    $ xl create zephyr.conf
 
-Next you need to attach to SBSA virtual console:
+Next you need to attach to PV console:
+
+.. code-block::
+
+   $ xl console zephyr
+
+Also this can be performed via single command:
 
 .. code-block::
 
-   $ xl console -t vuart zephyr
+   $ xl create -c zephyr.conf
 
 You will see Zephyr output:
 

boards/arm64/xenvm/xenvm.dts

@@ -25,9 +25,8 @@
 	#size-cells = <0x02>;
 
 	chosen {
-		zephyr,console = &sbsa;
-		zephyr,shell-uart = &sbsa;
 		zephyr,sram = &ram;
+		zephyr,console = &xen_hvc;
 	};
 
 	cpus {
@@ -78,12 +77,8 @@
 		interrupt-parent = <&gic>;
 	};
 
-	sbsa: sbsa-pl011@22000000 {
-		compatible = "arm,sbsa-uart";
-		reg = <0x00 0x22000000 0x00 0x1000>;
-		interrupts = <GIC_SPI 0x00 IRQ_TYPE_LEVEL IRQ_DEFAULT_PRIORITY>;
-		interrupt-parent = <&gic>;
-		current-speed = <0x1c200>;
-		label = "UART";
+	xen_hvc: hvc {
+		compatible = "xen,uart_hvc";
+		status = "okay";
 	};
 };

boards/arm64/xenvm/xenvm_defconfig

@@ -14,7 +14,9 @@ CONFIG_MAX_XLAT_TABLES=10
 CONFIG_CONSOLE=y
 CONFIG_UART_CONSOLE=y
 
-# Enable serial port
-CONFIG_UART_PL011=y
-CONFIG_UART_PL011_SBSA=y
-CONFIG_UART_INTERRUPT_DRIVEN=n
+# Enable PV hypervisor console
+CONFIG_UART_XEN_HVC=y
+
+# Enable logging subsys
+CONFIG_LOG=y
+CONFIG_LOG_MODE_MINIMAL=y

drivers/CMakeLists.txt

@@ -63,3 +63,4 @@ add_subdirectory_ifdef(CONFIG_BBRAM            bbram)
 add_subdirectory_ifdef(CONFIG_FPGA             fpga)
 add_subdirectory_ifdef(CONFIG_PINCTRL pinctrl)
 add_subdirectory_ifdef(CONFIG_MBOX             mbox)
+add_subdirectory_ifdef(CONFIG_BOARD_XENVM xen)

drivers/serial/CMakeLists.txt

@@ -45,6 +45,7 @@ zephyr_library_sources_ifdef(CONFIG_UART_RCAR uart_rcar.c)
 zephyr_library_sources_ifdef(CONFIG_UART_XEC uart_mchp_xec.c)
 zephyr_library_sources_ifdef(CONFIG_UART_NEORV32 uart_neorv32.c)
 zephyr_library_sources_ifdef(CONFIG_USART_GD32 usart_gd32.c)
+zephyr_library_sources_ifdef(CONFIG_UART_XEN_HVC uart_hvc_xen.c)
 
 zephyr_library_sources_ifdef(CONFIG_USERSPACE   uart_handlers.c)
 

drivers/serial/Kconfig

@@ -171,4 +171,6 @@ source "drivers/serial/Kconfig.test"
 
 source "drivers/serial/Kconfig.neorv32"
 
+source "drivers/serial/Kconfig.xen"
+
 endif # SERIAL

drivers/serial/Kconfig.xen

@@ -0,0 +1,30 @@
+# Xen hypervisor console via UART setup
+#
+# Copyright (c) 2021 EPAM Systems
+# SPDX-License-Identifier: Apache-2.0
+#
+
+config UART_XEN_HVC
+	bool "Xen hypervisor console UART Driver"
+	select SERIAL_HAS_DRIVER
+	depends on BOARD_XENVM
+	default y
+	help
+	  Enable Xen hypervisor console driver.
+
+config XEN_HVC_INIT_PRIORITY
+	int "Xen hypervisor console init priority"
+	depends on UART_XEN_HVC
+	default 55
+	help
+	  Set init priority for Xen HVC, should be inited before UART
+	  console driver (HVC gets inited on PRE_KERNEL_1 stage).
+
+config XEN_EARLY_CONSOLEIO
+	bool "Early printk/stdout through console_io Xen interface"
+	depends on BOARD_XENVM
+	default n
+	help
+	  Enable setting of console_io symbol hook for stdout and printk.
+	  Log output will become available on PRE_KERNEL_1 stage. Requires
+	  Xen, compiled with CONFIG_DEBUG flag.