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

arch/x86/Kconfig

@@ -796,6 +796,14 @@ config PARAVIRT_TIME_ACCOUNTING
 config PARAVIRT_CLOCK
 	bool
 
+config JAILHOUSE_GUEST
+	bool "Jailhouse non-root cell support"
+	depends on X86_64
+	---help---
+	  This option allows to run Linux as guest in a Jailhouse non-root
+	  cell. You can leave this option disabled if you only want to start
+	  Jailhouse and run Linux afterwards in the root cell.
+
 endif #HYPERVISOR_GUEST
 
 config NO_BOOTMEM

arch/x86/include/asm/hypervisor.h

@@ -28,6 +28,7 @@ enum x86_hypervisor_type {
 	X86_HYPER_XEN_PV,
 	X86_HYPER_XEN_HVM,
 	X86_HYPER_KVM,
+	X86_HYPER_JAILHOUSE,
 };
 
 #ifdef CONFIG_HYPERVISOR_GUEST

arch/x86/include/asm/jailhouse_para.h

@@ -0,0 +1,26 @@
+/* SPDX-License-Identifier: GPL2.0 */
+
+/*
+ * Jailhouse paravirt_ops implementation
+ *
+ * Copyright (c) Siemens AG, 2015-2017
+ *
+ * Authors:
+ *  Jan Kiszka <jan.kiszka@siemens.com>
+ */
+
+#ifndef _ASM_X86_JAILHOUSE_PARA_H
+#define _ASM_X86_JAILHOUSE_PARA_H
+
+#include <linux/types.h>
+
+#ifdef CONFIG_JAILHOUSE_GUEST
+bool jailhouse_paravirt(void);
+#else
+static inline bool jailhouse_paravirt(void)
+{
+	return false;
+}
+#endif
+
+#endif /* _ASM_X86_JAILHOUSE_PARA_H */

arch/x86/include/uapi/asm/bootparam.h

@@ -9,6 +9,7 @@
 #define SETUP_PCI			3
 #define SETUP_EFI			4
 #define SETUP_APPLE_PROPERTIES		5
+#define SETUP_JAILHOUSE			6
 
 /* ram_size flags */
 #define RAMDISK_IMAGE_START_MASK	0x07FF
@@ -126,6 +127,27 @@ struct boot_e820_entry {
 	__u32 type;
 } __attribute__((packed));
 
+/*
+ * Smallest compatible version of jailhouse_setup_data required by this kernel.
+ */
+#define JAILHOUSE_SETUP_REQUIRED_VERSION	1
+
+/*
+ * The boot loader is passing platform information via this Jailhouse-specific
+ * setup data structure.
+ */
+struct jailhouse_setup_data {
+	u16	version;
+	u16	compatible_version;
+	u16	pm_timer_address;
+	u16	num_cpus;
+	u64	pci_mmconfig_base;
+	u32	tsc_khz;
+	u32	apic_khz;
+	u8	standard_ioapic;
+	u8	cpu_ids[255];
+} __attribute__((packed));
+
 /* The so-called "zeropage" */
 struct boot_params {
 	struct screen_info screen_info;			/* 0x000 */

arch/x86/kernel/Makefile

@@ -112,6 +112,8 @@ obj-$(CONFIG_PARAVIRT_SPINLOCKS)+= paravirt-spinlocks.o
 obj-$(CONFIG_PARAVIRT_CLOCK)	+= pvclock.o
 obj-$(CONFIG_X86_PMEM_LEGACY_DEVICE) += pmem.o
 
+obj-$(CONFIG_JAILHOUSE_GUEST)	+= jailhouse.o
+
 obj-$(CONFIG_EISA)		+= eisa.o
 obj-$(CONFIG_PCSPKR_PLATFORM)	+= pcspeaker.o
 

arch/x86/kernel/cpu/hypervisor.c

@@ -31,6 +31,7 @@ extern const struct hypervisor_x86 x86_hyper_ms_hyperv;
 extern const struct hypervisor_x86 x86_hyper_xen_pv;
 extern const struct hypervisor_x86 x86_hyper_xen_hvm;
 extern const struct hypervisor_x86 x86_hyper_kvm;
+extern const struct hypervisor_x86 x86_hyper_jailhouse;
 
 static const __initconst struct hypervisor_x86 * const hypervisors[] =
 {
@@ -45,6 +46,9 @@ static const __initconst struct hypervisor_x86 * const hypervisors[] =
 #ifdef CONFIG_KVM_GUEST
 	&x86_hyper_kvm,
 #endif
+#ifdef CONFIG_JAILHOUSE_GUEST
+	&x86_hyper_jailhouse,
+#endif
 };
 
 enum x86_hypervisor_type x86_hyper_type;

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,
+};