[RFC PATCH v2 1/3] arch/x86: add the support of ACRN guest

[Zhao Yakui]

ACRN is one open-source hypervisour, which is maintained by Linux
foundation. This is to add the para-virtualization support so that
it allows the Linux guest to run on acrn-hypervisor.

This adds x86_hyper_acrn into supported hypervisors array, which enables
Linux ACRN guest running on ACRN hypervisor. It is restricted to X86_64.

v1->v2: Change the CONFIG_ACRN to CONFIG_ACRN_GUEST, which makes it easy to
understand.
        Remove the export of x86_hyper_acrn.

Co-developed-by: Jason Chen CJ <jason.cj.chen@xxxxxxxxx>
Signed-off-by: Jason Chen CJ <jason.cj.chen@xxxxxxxxx>
Signed-off-by: Zhao Yakui <yakui.zhao@xxxxxxxxx>
---
 arch/x86/Kconfig                  |  8 ++++++++
 arch/x86/include/asm/hypervisor.h |  1 +
 arch/x86/kernel/cpu/Makefile      |  1 +
 arch/x86/kernel/cpu/acrn.c        | 35 +++++++++++++++++++++++++++++++++++
 arch/x86/kernel/cpu/hypervisor.c  |  4 ++++
 5 files changed, 49 insertions(+)
 create mode 100644 arch/x86/kernel/cpu/acrn.c

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index c1f9b3c..d73225e 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -842,6 +842,14 @@ config JAILHOUSE_GUEST
 	  cell. You can leave this option disabled if you only want to start
 	  Jailhouse and run Linux afterwards in the root cell.
 
+config ACRN_GUEST
+	bool "ACRN Guest support"
+	depends on X86_64 && PARAVIRT
+	help
+	  This option allows to run Linux as guest in ACRN hypervisor. Enabling
+	  this will allow the kernel to boot in a paravirtualized environment
+	  under the ACRN hypervisor.
+
 endif #HYPERVISOR_GUEST
 
 source "arch/x86/Kconfig.cpu"
diff --git a/arch/x86/include/asm/hypervisor.h b/arch/x86/include/asm/hypervisor.h
index 8c5aaba..50a30f6 100644
--- a/arch/x86/include/asm/hypervisor.h
+++ b/arch/x86/include/asm/hypervisor.h
@@ -29,6 +29,7 @@ enum x86_hypervisor_type {
 	X86_HYPER_XEN_HVM,
 	X86_HYPER_KVM,
 	X86_HYPER_JAILHOUSE,
+	X86_HYPER_ACRN,
 };
 
 #ifdef CONFIG_HYPERVISOR_GUEST
diff --git a/arch/x86/kernel/cpu/Makefile b/arch/x86/kernel/cpu/Makefile
index cfd24f9..17a7cdf 100644
--- a/arch/x86/kernel/cpu/Makefile
+++ b/arch/x86/kernel/cpu/Makefile
@@ -44,6 +44,7 @@ obj-$(CONFIG_X86_CPU_RESCTRL)		+= resctrl/
 obj-$(CONFIG_X86_LOCAL_APIC)		+= perfctr-watchdog.o
 
 obj-$(CONFIG_HYPERVISOR_GUEST)		+= vmware.o hypervisor.o mshyperv.o
+obj-$(CONFIG_ACRN_GUEST)		+= acrn.o
 
 ifdef CONFIG_X86_FEATURE_NAMES
 quiet_cmd_mkcapflags = MKCAP   $@
diff --git a/arch/x86/kernel/cpu/acrn.c b/arch/x86/kernel/cpu/acrn.c
new file mode 100644
index 0000000..3956567
--- /dev/null
+++ b/arch/x86/kernel/cpu/acrn.c
@@ -0,0 +1,35 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ACRN detection support
+ *
+ * Copyright (C) 2019 Intel Corporation. All rights reserved.
+ *
+ * Jason Chen CJ <jason.cj.chen@xxxxxxxxx>
+ * Zhao Yakui <yakui.zhao@xxxxxxxxx>
+ *
+ */
+
+#include <asm/hypervisor.h>
+
+static uint32_t __init acrn_detect(void)
+{
+	return hypervisor_cpuid_base("ACRNACRNACRN\0\0", 0);
+}
+
+static void __init acrn_init_platform(void)
+{
+}
+
+static bool acrn_x2apic_available(void)
+{
+	/* do not support x2apic */
+	return false;
+}
+
+const __initconst struct hypervisor_x86 x86_hyper_acrn = {
+	.name                   = "ACRN",
+	.detect                 = acrn_detect,
+	.type			= X86_HYPER_ACRN,
+	.init.init_platform     = acrn_init_platform,
+	.init.x2apic_available  = acrn_x2apic_available,
+};
diff --git a/arch/x86/kernel/cpu/hypervisor.c b/arch/x86/kernel/cpu/hypervisor.c
index 479ca47..87e39ad 100644
--- a/arch/x86/kernel/cpu/hypervisor.c
+++ b/arch/x86/kernel/cpu/hypervisor.c
@@ -32,6 +32,7 @@ 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;
+extern const struct hypervisor_x86 x86_hyper_acrn;
 
 static const __initconst struct hypervisor_x86 * const hypervisors[] =
 {
@@ -49,6 +50,9 @@ static const __initconst struct hypervisor_x86 * const hypervisors[] =
 #ifdef CONFIG_JAILHOUSE_GUEST
 	&x86_hyper_jailhouse,
 #endif
+#ifdef CONFIG_ACRN_GUEST
+	&x86_hyper_acrn,
+#endif
 };
 
 enum x86_hypervisor_type x86_hyper_type;
-- 
2.7.4