[AGL/meta-agl-devel.git] /

From faa349f4d096554c6d5bfe74634599d2e26f64a7 Mon Sep 17 00:00:00 2001
From: Jan Kiszka <jan.kiszka@siemens.com>
Date: Sun, 11 Sep 2016 23:30:04 +0200
Subject: [PATCH 03/32] 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 <jan.kiszka@siemens.com>
---
 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

diff --git a/MAINTAINERS b/MAINTAINERS
index 9d3a5c54a41d..07cb4d674c93 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -8761,6 +8761,7 @@ 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 <linux@roeck-us.net>
diff --git a/drivers/virt/Kconfig b/drivers/virt/Kconfig
index 363af2eaf2ba..99c5eaca6952 100644
--- 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
diff --git a/drivers/virt/Makefile b/drivers/virt/Makefile
index fd331247c27a..89e86a1d0f19 100644
--- 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/
diff --git a/drivers/virt/jailhouse_dbgcon.c b/drivers/virt/jailhouse_dbgcon.c
new file mode 100644
index 000000000000..1fd201ea1460
--- /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 <jan.kiszka@siemens.com>
+ */
+
+#include <linux/console.h>
+#include <linux/hypervisor.h>
+#include <linux/module.h>
+#include <linux/serial_core.h>
+#ifdef CONFIG_X86
+#include <asm/alternative.h>
+#endif
+#ifdef CONFIG_ARM
+#include <asm/opcodes-virt.h>
+#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 <jan.kiszka@siemens.com>");
-- 
2.11.0