x86: introduce CONFIG_HYPERV and detection code

We use the same code structure as we did for Xen.

As starters, detect Hyper-V in probe routine. More complex
functionalities will be added later.

Signed-off-by: Wei Liu <liuwe@microsoft.com>
Reviewed-by: Paul Durrant <pdurrant@amazon.com>
Acked-by: Jan Beulich <jbeulich@suse.com>

xen/arch/x86/Kconfig

@@ -164,6 +164,14 @@ endchoice
 config GUEST
 	bool
 
+config HYPERV_GUEST
+	bool "Hyper-V Guest"
+	select GUEST
+	---help---
+	  Support for Xen detecting when it is running under Hyper-V.
+
+	  If unsure, say N.
+
 config XEN_GUEST
 	bool "Xen Guest"
 	select GUEST

xen/arch/x86/guest/Makefile

@@ -1,3 +1,4 @@
 obj-y += hypervisor.o
 
+subdir-$(CONFIG_HYPERV_GUEST) += hyperv
 subdir-$(CONFIG_XEN_GUEST) += xen

xen/arch/x86/guest/hyperv/Makefile

@@ -0,0 +1 @@
+obj-y += hyperv.o

xen/arch/x86/guest/hyperv/hyperv.c

@@ -0,0 +1,54 @@
+/******************************************************************************
+ * arch/x86/guest/hyperv/hyperv.c
+ *
+ * Support for detecting and running under Hyper-V.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Copyright (c) 2019 Microsoft.
+ */
+#include <xen/init.h>
+
+#include <asm/guest.h>
+
+static const struct hypervisor_ops ops = {
+    .name = "Hyper-V",
+};
+
+const struct hypervisor_ops *__init hyperv_probe(void)
+{
+    uint32_t eax, ebx, ecx, edx;
+
+    cpuid(0x40000000, &eax, &ebx, &ecx, &edx);
+    if ( !((ebx == 0x7263694d) &&  /* "Micr" */
+           (ecx == 0x666f736f) &&  /* "osof" */
+           (edx == 0x76482074)) )  /* "t Hv" */
+        return NULL;
+
+    cpuid(0x40000001, &eax, &ebx, &ecx, &edx);
+    if ( eax != 0x31237648 )    /* Hv#1 */
+        return NULL;
+
+    return &ops;
+}
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * tab-width: 4
+ * indent-tabs-mode: nil
+ * End:
+ */

xen/arch/x86/guest/hypervisor.c

@@ -35,6 +35,14 @@ const char *__init hypervisor_probe(void)
     if ( ops )
         return ops->name;
 
+    /*
+     * Detection of Hyper-V must come after Xen to avoid false positive due
+     * to viridian support
+     */
+    ops = hyperv_probe();
+    if ( ops )
+        return ops->name;
+
     return NULL;
 }
 

xen/include/asm-x86/guest.h

@@ -20,6 +20,7 @@
 #define __X86_GUEST_H__
 
 #include <asm/guest/hypercall.h>
+#include <asm/guest/hyperv.h>
 #include <asm/guest/hypervisor.h>
 #include <asm/guest/pvh-boot.h>
 #include <asm/guest/xen.h>

xen/include/asm-x86/guest/hyperv.h

@@ -0,0 +1,43 @@
+/******************************************************************************
+ * asm-x86/guest/hyperv.h
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms and conditions of the GNU General Public
+ * License, version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Copyright (c) 2019 Microsoft.
+ */
+
+#ifndef __X86_GUEST_HYPERV_H__
+#define __X86_GUEST_HYPERV_H__
+
+#ifdef CONFIG_HYPERV_GUEST
+
+#include <asm/guest/hypervisor.h>
+
+const struct hypervisor_ops *hyperv_probe(void);
+
+#else
+
+static inline const struct hypervisor_ops *hyperv_probe(void) { return NULL; }
+
+#endif /* CONFIG_HYPERV_GUEST */
+#endif /* __X86_GUEST_HYPERV_H__ */
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * tab-width: 4
+ * indent-tabs-mode: nil
+ * End:
+ */