[PATCH 12/24] xen/arm: Introduce xen_guest_init

[Stefano Stabellini <stefano.stabellini-mvvWK6WmYclDPfheJLI6IQ@public.gmane.org>]

We used to rely on a core_initcall to initialize Xen on ARM, however
core_initcalls are actually called after early consoles are initialized.
That means that hvc_xen.c is going to be initialized before Xen.

Given the lack of a better alternative, just call a new Xen
initialization function (xen_guest_init) from xen_cons_init.

xen_guest_init has to be arch independent, so write both an ARM and an
x86 implementation. The x86 implementation is currently empty because we
can be sure that xen_hvm_guest_init is called early enough.

Signed-off-by: Stefano Stabellini <stefano.stabellini-mvvWK6WmYclDPfheJLI6IQ@public.gmane.org>
---
 arch/arm/xen/enlighten.c  |    7 ++++++-
 arch/x86/xen/enlighten.c  |    8 ++++++++
 drivers/tty/hvc/hvc_xen.c |    7 ++++++-
 include/xen/xen.h         |    2 ++
 4 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c
index 8c923af..dc68074 100644
--- a/arch/arm/xen/enlighten.c
+++ b/arch/arm/xen/enlighten.c
@@ -44,7 +44,7 @@ EXPORT_SYMBOL_GPL(xen_remap_domain_mfn_range);
  * - one interrupt for Xen event notifications;
  * - one memory region to map the grant_table.
  */
-static int __init xen_guest_init(void)
+int __init xen_guest_init(void)
 {
 	int cpu;
 	struct xen_add_to_physmap xatp;
@@ -58,6 +58,10 @@ static int __init xen_guest_init(void)
 	}
 	xen_domain_type = XEN_HVM_DOMAIN;
 
+	/* already setup */
+	if (shared_info_page != 0 && HYPERVISOR_shared_info == shared_info_page)
+		return 0;
+
 	if (!shared_info_page)
 		shared_info_page = (struct shared_info *)
 			get_zeroed_page(GFP_KERNEL);
@@ -88,4 +92,5 @@ static int __init xen_guest_init(void)
 	}
 	return 0;
 }
+EXPORT_SYMBOL_GPL(xen_guest_init);
 core_initcall(xen_guest_init);
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index ff962d4..6131d43 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1567,4 +1567,12 @@ const struct hypervisor_x86 x86_hyper_xen_hvm __refconst = {
 	.init_platform		= xen_hvm_guest_init,
 };
 EXPORT_SYMBOL(x86_hyper_xen_hvm);
+
+int __init xen_guest_init(void)
+{
+	/* do nothing: rely on x86_hyper_xen_hvm for the initialization */
+	return 0;
+	
+}
+EXPORT_SYMBOL_GPL(xen_guest_init);
 #endif
diff --git a/drivers/tty/hvc/hvc_xen.c b/drivers/tty/hvc/hvc_xen.c
index dc07f56..3c04fb8 100644
--- a/drivers/tty/hvc/hvc_xen.c
+++ b/drivers/tty/hvc/hvc_xen.c
@@ -577,6 +577,12 @@ static void __exit xen_hvc_fini(void)
 static int xen_cons_init(void)
 {
 	const struct hv_ops *ops;
+	int r;
+
+	/* retrieve xen infos  */
+	r = xen_guest_init();
+	if (r < 0)
+		return r;
 
 	if (!xen_domain())
 		return 0;
@@ -584,7 +590,6 @@ static int xen_cons_init(void)
 	if (xen_initial_domain())
 		ops = &dom0_hvc_ops;
 	else {
-		int r;
 		ops = &domU_hvc_ops;
 
 		if (xen_hvm_domain())
diff --git a/include/xen/xen.h b/include/xen/xen.h
index 2c0d3a5..792a4d2 100644
--- a/include/xen/xen.h
+++ b/include/xen/xen.h
@@ -9,8 +9,10 @@ enum xen_domain_type {
 
 #ifdef CONFIG_XEN
 extern enum xen_domain_type xen_domain_type;
+int xen_guest_init(void);
 #else
 #define xen_domain_type		XEN_NATIVE
+static inline int xen_guest_init(void) { return 0; }
 #endif
 
 #define xen_domain()		(xen_domain_type != XEN_NATIVE)
-- 
1.7.2.5