git.openwrt.org Git - openwrt/staging/xback.git/blob

   1 From 58d058f1fe1cc5981c57be8b48d3b2f74f25c0d6 Mon Sep 17 00:00:00 2001
   2 From: Jan Kiszka <jan.kiszka@siemens.com>
   3 Date: Sun, 11 Sep 2016 23:30:04 +0200
   4 Subject: [PATCH] jailhouse: Add simple debug console via the hypervisor
   5
   6 Jailhouse allows explicitly enabled cells to write character-wise
   7 messages to the hypervisor debug console. Make use of this for a
   8 platform-agnostic boot diagnosis channel, specifically for non-root
   9 cells. This also comes with earlycon support.
  10
  11 Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
  12 (cherry picked from commit 60685bd589aef4972d20724863079edf2039eaa2)
  13 From http://git.kiszka.org/?p=linux.git;a=shortlog;h=refs/heads/queues/jailhouse
  14 ---
  15  MAINTAINERS                     |   1 +
  16  drivers/virt/Kconfig            |  11 +++++
  17  drivers/virt/Makefile           |   1 +
  18  drivers/virt/jailhouse_dbgcon.c | 103 ++++++++++++++++++++++++++++++++++++++++
  19  4 files changed, 116 insertions(+)
  20  create mode 100644 drivers/virt/jailhouse_dbgcon.c
  21
  22 --- a/MAINTAINERS
  23 +++ b/MAINTAINERS
  24 @@ -8773,6 +8773,7 @@ L:        jailhouse-dev@googlegroups.com
  25  S:     Maintained
  26  F:     arch/x86/kernel/jailhouse.c
  27  F:     arch/x86/include/asm/jailhouse_para.h
  28 +F:     drivers/virt/jailhouse_dbgcon.c
  29
  30  JC42.4 TEMPERATURE SENSOR DRIVER
  31  M:     Guenter Roeck <linux@roeck-us.net>
  32 --- a/drivers/virt/Kconfig
  33 +++ b/drivers/virt/Kconfig
  34 @@ -31,5 +31,16 @@ config FSL_HV_MANAGER
  35            4) A kernel interface for receiving callbacks when a managed
  36              partition shuts down.
  37
  38 +config JAILHOUSE_DBGCON
  39 +       tristate "Jailhouse console driver"
  40 +       depends on X86 || ARM || ARM64
  41 +       help
  42 +         The Jailhouse hypervisor provides a simple write-only console for
  43 +         debugging the bootstrap process of its cells. This driver registers
  44 +         a console with the kernel to make use of it.
  45 +
  46 +         Note that Jailhouse has to be configured to permit a cell the usage
  47 +         of the console interface.
  48 +
  49  source "drivers/virt/vboxguest/Kconfig"
  50  endif
  51 --- a/drivers/virt/Makefile
  52 +++ b/drivers/virt/Makefile
  53 @@ -4,4 +4,5 @@
  54  #
  55
  56  obj-$(CONFIG_FSL_HV_MANAGER)   += fsl_hypervisor.o
  57 +obj-$(CONFIG_JAILHOUSE_DBGCON) += jailhouse_dbgcon.o
  58  obj-y                          += vboxguest/
  59 --- /dev/null
  60 +++ b/drivers/virt/jailhouse_dbgcon.c
  61 @@ -0,0 +1,103 @@
  62 +/* SPDX-License-Identifier: GPL-2.0 */
  63 +/*
  64 + * Console driver for running over the Jailhouse partitioning hypervisor
  65 + *
  66 + * Copyright (c) Siemens AG, 2016-2018
  67 + *
  68 + * Authors:
  69 + *  Jan Kiszka <jan.kiszka@siemens.com>
  70 + */
  71 +
  72 +#include <linux/console.h>
  73 +#include <linux/hypervisor.h>
  74 +#include <linux/module.h>
  75 +#include <linux/serial_core.h>
  76 +#ifdef CONFIG_X86
  77 +#include <asm/alternative.h>
  78 +#endif
  79 +#ifdef CONFIG_ARM
  80 +#include <asm/opcodes-virt.h>
  81 +#endif
  82 +
  83 +#define JAILHOUSE_HC_DEBUG_CONSOLE_PUTC                8
  84 +
  85 +static void hypervisor_putc(char c)
  86 +{
  87 +#if defined(CONFIG_X86)
  88 +       int result;
  89 +
  90 +       asm volatile(
  91 +               ALTERNATIVE(".byte 0x0f,0x01,0xc1", ".byte 0x0f,0x01,0xd9",
  92 +                           X86_FEATURE_VMMCALL)
  93 +               : "=a" (result)
  94 +               : "a" (JAILHOUSE_HC_DEBUG_CONSOLE_PUTC), "D" (c)
  95 +               : "memory");
  96 +#elif defined(CONFIG_ARM)
  97 +       register u32 num_res asm("r0") = JAILHOUSE_HC_DEBUG_CONSOLE_PUTC;
  98 +       register u32 arg1 asm("r1") = c;
  99 +
 100 +       asm volatile(
 101 +               __HVC(0x4a48)
 102 +               : "=r" (num_res)
 103 +               : "r" (num_res), "r" (arg1)
 104 +               : "memory");
 105 +#elif defined(CONFIG_ARM64)
 106 +       register u64 num_res asm("x0") = JAILHOUSE_HC_DEBUG_CONSOLE_PUTC;
 107 +       register u64 arg1 asm("x1") = c;
 108 +
 109 +       asm volatile(
 110 +               "hvc #0x4a48\n\t"
 111 +               : "=r" (num_res)
 112 +               : "r" (num_res), "r" (arg1)
 113 +               : "memory");
 114 +#else
 115 +#error Unsupported architecture.
 116 +#endif
 117 +}
 118 +
 119 +static void jailhouse_dbgcon_write(struct console *con, const char *s,
 120 +                                  unsigned count)
 121 +{
 122 +       while (count > 0) {
 123 +               hypervisor_putc(*s);
 124 +               count--;
 125 +               s++;
 126 +       }
 127 +}
 128 +
 129 +static int __init early_jailhouse_dbgcon_setup(struct earlycon_device *device,
 130 +                                              const char *options)
 131 +{
 132 +       device->con->write = jailhouse_dbgcon_write;
 133 +       return 0;
 134 +}
 135 +
 136 +EARLYCON_DECLARE(jailhouse, early_jailhouse_dbgcon_setup);
 137 +
 138 +static struct console jailhouse_dbgcon = {
 139 +       .name = "jailhouse",
 140 +       .write = jailhouse_dbgcon_write,
 141 +       .flags = CON_PRINTBUFFER | CON_ANYTIME,
 142 +       .index = -1,
 143 +};
 144 +
 145 +static int __init jailhouse_dbgcon_init(void)
 146 +{
 147 +       if (!jailhouse_paravirt())
 148 +               return -ENODEV;
 149 +
 150 +       register_console(&jailhouse_dbgcon);
 151 +       return 0;
 152 +}
 153 +
 154 +static void __exit jailhouse_dbgcon_exit(void)
 155 +{
 156 +       unregister_console(&jailhouse_dbgcon);
 157 +}
 158 +
 159 +module_init(jailhouse_dbgcon_init);
 160 +module_exit(jailhouse_dbgcon_exit);
 161 +
 162 +MODULE_LICENSE("GPL v2");
 163 +MODULE_DESCRIPTION("Jailhouse debug console driver");
 164 +MODULE_AUTHOR("Jan Kiszka <jan.kiszka@siemens.com>");