We will soon implement Hyper-V support for Xen. Add a framework for
that.

This requires moving some of the hypervisor_* functions from xen.h to
hypervisor.h.

Signed-off-by: Wei Liu <liuwe@microsoft.com>
---
Changes in v5:
1. Make hypervisor_probe return const char *.

Changes in v4:
1. Add ASSERT_UNREACHABLE to stubs.
2. Move __read_mostly.
3. Return hops directly.
4. Drop Paul's review tag.
---
 xen/arch/x86/guest/Makefile            |  2 +
 xen/arch/x86/guest/hypervisor.c        | 45 +++++++++++++++++++
 xen/include/asm-x86/guest.h            |  1 +
 xen/include/asm-x86/guest/hypervisor.h | 62 ++++++++++++++++++++++++++
 xen/include/asm-x86/guest/xen.h        | 12 -----
 5 files changed, 110 insertions(+), 12 deletions(-)
 create mode 100644 xen/arch/x86/guest/hypervisor.c
 create mode 100644 xen/include/asm-x86/guest/hypervisor.h

diff --git a/xen/arch/x86/guest/Makefile b/xen/arch/x86/guest/Makefile
index 6806f04947..f63d64bbee 100644
--- a/xen/arch/x86/guest/Makefile
+++ b/xen/arch/x86/guest/Makefile
@@ -1 +1,3 @@
+obj-y += hypervisor.o
+
 subdir-$(CONFIG_XEN_GUEST) += xen
diff --git a/xen/arch/x86/guest/hypervisor.c b/xen/arch/x86/guest/hypervisor.c
new file mode 100644
index 0000000000..c35c610d01
--- /dev/null
+++ b/xen/arch/x86/guest/hypervisor.c
@@ -0,0 +1,45 @@
+/******************************************************************************
+ * arch/x86/guest/hypervisor.c
+ *
+ * Support for detecting and running under a hypervisor.
+ *
+ * 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 <xen/types.h>
+
+#include <asm/cache.h>
+#include <asm/guest/hypervisor.h>
+
+static const struct hypervisor_ops __read_mostly *ops;
+
+const char *__init hypervisor_probe(void)
+{
+    if ( ops )
+        return ops->name;
+
+    return NULL;
+}
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * tab-width: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/xen/include/asm-x86/guest.h b/xen/include/asm-x86/guest.h
index a38c6b5b3f..8e167165ae 100644
--- a/xen/include/asm-x86/guest.h
+++ b/xen/include/asm-x86/guest.h
@@ -20,6 +20,7 @@
 #define __X86_GUEST_H__
 
 #include <asm/guest/hypercall.h>
+#include <asm/guest/hypervisor.h>
 #include <asm/guest/pvh-boot.h>
 #include <asm/guest/xen.h>
 #include <asm/pv/shim.h>
diff --git a/xen/include/asm-x86/guest/hypervisor.h b/xen/include/asm-x86/guest/hypervisor.h
new file mode 100644
index 0000000000..392f4b90ae
--- /dev/null
+++ b/xen/include/asm-x86/guest/hypervisor.h
@@ -0,0 +1,62 @@
+/******************************************************************************
+ * asm-x86/guest/hypervisor.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_HYPERVISOR_H__
+#define __X86_HYPERVISOR_H__
+
+struct hypervisor_ops {
+    /* Name of the hypervisor */
+    const char *name;
+    /* Main setup routine */
+    void (*setup)(void);
+    /* AP setup */
+    void (*ap_setup)(void);
+    /* Resume from suspension */
+    void (*resume)(void);
+};
+
+#ifdef CONFIG_GUEST
+
+const char *hypervisor_probe(void);
+void hypervisor_setup(void);
+void hypervisor_ap_setup(void);
+void hypervisor_resume(void);
+
+#else
+
+#include <xen/lib.h>
+#include <xen/types.h>
+
+static inline const char *hypervisor_probe(void) { return NULL; }
+static inline void hypervisor_setup(void) { ASSERT_UNREACHABLE(); }
+static inline void hypervisor_ap_setup(void) { ASSERT_UNREACHABLE(); }
+static inline void hypervisor_resume(void) { ASSERT_UNREACHABLE(); }
+
+#endif  /* CONFIG_GUEST */
+
+#endif /* __X86_HYPERVISOR_H__ */
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * tab-width: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/xen/include/asm-x86/guest/xen.h b/xen/include/asm-x86/guest/xen.h
index b015ed1883..3145f75361 100644
--- a/xen/include/asm-x86/guest/xen.h
+++ b/xen/include/asm-x86/guest/xen.h
@@ -33,11 +33,8 @@ extern bool pv_console;
 extern uint32_t xen_cpuid_base;
 
 void probe_hypervisor(void);
-void hypervisor_setup(void);
-void hypervisor_ap_setup(void);
 int hypervisor_alloc_unused_page(mfn_t *mfn);
 int hypervisor_free_unused_page(mfn_t mfn);
-void hypervisor_resume(void);
 
 DECLARE_PER_CPU(unsigned int, vcpu_id);
 DECLARE_PER_CPU(struct vcpu_info *, vcpu_info);
@@ -49,15 +46,6 @@ DECLARE_PER_CPU(struct vcpu_info *, vcpu_info);
 
 static inline void probe_hypervisor(void) {}
 
-static inline void hypervisor_setup(void)
-{
-    ASSERT_UNREACHABLE();
-}
-static inline void hypervisor_ap_setup(void)
-{
-    ASSERT_UNREACHABLE();
-}
-
 #endif /* CONFIG_XEN_GUEST */
 #endif /* __X86_GUEST_XEN_H__ */
 
-- 
2.20.1


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On 30.11.2019 12:57, Wei Liu wrote:
> We will soon implement Hyper-V support for Xen. Add a framework for
> that.
> 
> This requires moving some of the hypervisor_* functions from xen.h to
> hypervisor.h.
> 
> Signed-off-by: Wei Liu <liuwe@microsoft.com>

Acked-by: Jan Beulich <jbeulich@suse.com>
with one more adjustment (sorry for noticing only now):

> --- /dev/null
> +++ b/xen/arch/x86/guest/hypervisor.c
> @@ -0,0 +1,45 @@
> +/******************************************************************************
> + * arch/x86/guest/hypervisor.c
> + *
> + * Support for detecting and running under a hypervisor.
> + *
> + * 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 <xen/types.h>
> +
> +#include <asm/cache.h>
> +#include <asm/guest/hypervisor.h>
> +
> +static const struct hypervisor_ops __read_mostly *ops;

The __read_mostly is misplaced - it's an attribute of the variable,
not its type, and hence belongs after the * . It just so happens
that the compiler is (still) relatively relaxed in what it accepts,
but I think at least the gcc manual has a warning towards future
more strict behavior.

Jan

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On Tue, Dec 03, 2019 at 03:49:33PM +0100, Jan Beulich wrote:
> On 30.11.2019 12:57, Wei Liu wrote:
> > We will soon implement Hyper-V support for Xen. Add a framework for
> > that.
> > 
> > This requires moving some of the hypervisor_* functions from xen.h to
> > hypervisor.h.
> > 
> > Signed-off-by: Wei Liu <liuwe@microsoft.com>
> 
> Acked-by: Jan Beulich <jbeulich@suse.com>
[...]
> > +#include <asm/guest/hypervisor.h>
> > +
> > +static const struct hypervisor_ops __read_mostly *ops;
> 
> The __read_mostly is misplaced - it's an attribute of the variable,
> not its type, and hence belongs after the * . It just so happens
> that the compiler is (still) relatively relaxed in what it accepts,
> but I think at least the gcc manual has a warning towards future
> more strict behavior.

Fixed.

Wei.

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