x86/jailhouse: Add infrastructure for running in non-root cell

The Jailhouse hypervisor is able to statically partition a multicore
system into multiple so-called cells. Linux is used as boot loader and
continues to run in the root cell after Jailhouse is enabled. Linux can
also run in non-root cells.

Jailhouse does not emulate usual x86 devices. It also provides no
complex ACPI but basic platform information that the boot loader
forwards via setup data. This adds the infrastructure to detect when
running in a non-root cell so that the platform can be configured as
required in succeeding steps.

Support is limited to x86-64 so far, primarily because no boot loader
stub exists for i386 and, thus, we wouldn't be able to test the 32-bit
path.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: jailhouse-dev@googlegroups.com
Link: https://lkml.kernel.org/r/7f823d077b38b1a70c526b40b403f85688c137d3.1511770314.git.jan.kiszka@siemens.com

1 files changed, 73 insertions, 0 deletions

diff --git a/arch/x86/kernel/jailhouse.c b/arch/x86/kernel/jailhouse.c
new file mode 100644
index 000000000000..1186b8909595
--- /dev/null
+++ b/arch/x86/kernel/jailhouse.c
@@ -0,0 +1,73 @@
+// SPDX-License-Identifier: GPL2.0
+/*
+ * Jailhouse paravirt_ops implementation
+ *
+ * Copyright (c) Siemens AG, 2015-2017
+ *
+ * Authors:
+ *  Jan Kiszka <jan.kiszka@siemens.com>
+ */
+
+#include <linux/kernel.h>
+#include <asm/cpu.h>
+#include <asm/hypervisor.h>
+#include <asm/setup.h>
+
+static __initdata struct jailhouse_setup_data setup_data;
+
+static uint32_t jailhouse_cpuid_base(void)
+{
+	if (boot_cpu_data.cpuid_level < 0 ||
+	    !boot_cpu_has(X86_FEATURE_HYPERVISOR))
+		return 0;
+
+	return hypervisor_cpuid_base("Jailhouse\0\0\0", 0);
+}
+
+static uint32_t __init jailhouse_detect(void)
+{
+	return jailhouse_cpuid_base();
+}
+
+static void __init jailhouse_init_platform(void)
+{
+	u64 pa_data = boot_params.hdr.setup_data;
+	struct setup_data header;
+	void *mapping;
+
+	while (pa_data) {
+		mapping = early_memremap(pa_data, sizeof(header));
+		memcpy(&header, mapping, sizeof(header));
+		early_memunmap(mapping, sizeof(header));
+
+		if (header.type == SETUP_JAILHOUSE &&
+		    header.len >= sizeof(setup_data)) {
+			pa_data += offsetof(struct setup_data, data);
+
+			mapping = early_memremap(pa_data, sizeof(setup_data));
+			memcpy(&setup_data, mapping, sizeof(setup_data));
+			early_memunmap(mapping, sizeof(setup_data));
+
+			break;
+		}
+
+		pa_data = header.next;
+	}
+
+	if (!pa_data)
+		panic("Jailhouse: No valid setup data found");
+
+	if (setup_data.compatible_version > JAILHOUSE_SETUP_REQUIRED_VERSION)
+		panic("Jailhouse: Unsupported setup data structure");
+}
+
+bool jailhouse_paravirt(void)
+{
+	return jailhouse_cpuid_base() != 0;
+}
+
+const struct hypervisor_x86 x86_hyper_jailhouse __refconst = {
+	.name			= "Jailhouse",
+	.detect			= jailhouse_detect,
+	.init.init_platform	= jailhouse_init_platform,
+};