From 58d058f1fe1cc5981c57be8b48d3b2f74f25c0d6 Mon Sep 17 00:00:00 2001 From: Jan Kiszka Date: Sun, 11 Sep 2016 23:30:04 +0200 Subject: [PATCH] jailhouse: Add simple debug console via the hypervisor Jailhouse allows explicitly enabled cells to write character-wise messages to the hypervisor debug console. Make use of this for a platform-agnostic boot diagnosis channel, specifically for non-root cells. This also comes with earlycon support. Signed-off-by: Jan Kiszka (cherry picked from commit 60685bd589aef4972d20724863079edf2039eaa2) From http://git.kiszka.org/?p=linux.git;a=shortlog;h=refs/heads/queues/jailhouse --- MAINTAINERS | 1 + drivers/virt/Kconfig | 11 +++++ drivers/virt/Makefile | 1 + drivers/virt/jailhouse_dbgcon.c | 103 ++++++++++++++++++++++++++++++++++++++++ 4 files changed, 116 insertions(+) create mode 100644 drivers/virt/jailhouse_dbgcon.c --- a/MAINTAINERS +++ b/MAINTAINERS @@ -8772,6 +8772,7 @@ L: jailhouse-dev@googlegroups.com S: Maintained F: arch/x86/kernel/jailhouse.c F: arch/x86/include/asm/jailhouse_para.h +F: drivers/virt/jailhouse_dbgcon.c JC42.4 TEMPERATURE SENSOR DRIVER M: Guenter Roeck --- a/drivers/virt/Kconfig +++ b/drivers/virt/Kconfig @@ -31,5 +31,16 @@ config FSL_HV_MANAGER 4) A kernel interface for receiving callbacks when a managed partition shuts down. +config JAILHOUSE_DBGCON + tristate "Jailhouse console driver" + depends on X86 || ARM || ARM64 + help + The Jailhouse hypervisor provides a simple write-only console for + debugging the bootstrap process of its cells. This driver registers + a console with the kernel to make use of it. + + Note that Jailhouse has to be configured to permit a cell the usage + of the console interface. + source "drivers/virt/vboxguest/Kconfig" endif --- a/drivers/virt/Makefile +++ b/drivers/virt/Makefile @@ -4,4 +4,5 @@ # obj-$(CONFIG_FSL_HV_MANAGER) += fsl_hypervisor.o +obj-$(CONFIG_JAILHOUSE_DBGCON) += jailhouse_dbgcon.o obj-y += vboxguest/ --- /dev/null +++ b/drivers/virt/jailhouse_dbgcon.c @@ -0,0 +1,103 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Console driver for running over the Jailhouse partitioning hypervisor + * + * Copyright (c) Siemens AG, 2016-2018 + * + * Authors: + * Jan Kiszka + */ + +#include +#include +#include +#include +#ifdef CONFIG_X86 +#include +#endif +#ifdef CONFIG_ARM +#include +#endif + +#define JAILHOUSE_HC_DEBUG_CONSOLE_PUTC 8 + +static void hypervisor_putc(char c) +{ +#if defined(CONFIG_X86) + int result; + + asm volatile( + ALTERNATIVE(".byte 0x0f,0x01,0xc1", ".byte 0x0f,0x01,0xd9", + X86_FEATURE_VMMCALL) + : "=a" (result) + : "a" (JAILHOUSE_HC_DEBUG_CONSOLE_PUTC), "D" (c) + : "memory"); +#elif defined(CONFIG_ARM) + register u32 num_res asm("r0") = JAILHOUSE_HC_DEBUG_CONSOLE_PUTC; + register u32 arg1 asm("r1") = c; + + asm volatile( + __HVC(0x4a48) + : "=r" (num_res) + : "r" (num_res), "r" (arg1) + : "memory"); +#elif defined(CONFIG_ARM64) + register u64 num_res asm("x0") = JAILHOUSE_HC_DEBUG_CONSOLE_PUTC; + register u64 arg1 asm("x1") = c; + + asm volatile( + "hvc #0x4a48\n\t" + : "=r" (num_res) + : "r" (num_res), "r" (arg1) + : "memory"); +#else +#error Unsupported architecture. +#endif +} + +static void jailhouse_dbgcon_write(struct console *con, const char *s, + unsigned count) +{ + while (count > 0) { + hypervisor_putc(*s); + count--; + s++; + } +} + +static int __init early_jailhouse_dbgcon_setup(struct earlycon_device *device, + const char *options) +{ + device->con->write = jailhouse_dbgcon_write; + return 0; +} + +EARLYCON_DECLARE(jailhouse, early_jailhouse_dbgcon_setup); + +static struct console jailhouse_dbgcon = { + .name = "jailhouse", + .write = jailhouse_dbgcon_write, + .flags = CON_PRINTBUFFER | CON_ANYTIME, + .index = -1, +}; + +static int __init jailhouse_dbgcon_init(void) +{ + if (!jailhouse_paravirt()) + return -ENODEV; + + register_console(&jailhouse_dbgcon); + return 0; +} + +static void __exit jailhouse_dbgcon_exit(void) +{ + unregister_console(&jailhouse_dbgcon); +} + +module_init(jailhouse_dbgcon_init); +module_exit(jailhouse_dbgcon_exit); + +MODULE_LICENSE("GPL v2"); +MODULE_DESCRIPTION("Jailhouse debug console driver"); +MODULE_AUTHOR("Jan Kiszka ");