[PATCH WIP 2/6] xen/arm: Introduce xen_guest_init

[Stefano Stabellini <stefano.stabellini@eu.citrix.com>]

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 independant, 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.

Probably we can get rid of this as soon as we have better DT support.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
---
 arch/arm/xen/enlighten.c  |   12 ++++++++----
 arch/x86/xen/enlighten.c  |    8 ++++++++
 drivers/tty/hvc/hvc_xen.c |    3 +++
 include/xen/xen.h         |    2 ++
 4 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c
index 7d76962..e1c2e4d 100644
--- a/arch/arm/xen/enlighten.c
+++ b/arch/arm/xen/enlighten.c
@@ -127,12 +127,16 @@ out:
 }
 EXPORT_SYMBOL_GPL(xen_remap_domain_mfn_range);
 
-void __ref xen_hvm_init_shared_info(void)
+static void __init xen_hvm_init_shared_info(void)
 {
 	int cpu;
 	struct xen_add_to_physmap xatp;
 	static struct shared_info *shared_info_page = 0;
 
+	/* already setup */
+	if (shared_info_page != 0 && HYPERVISOR_shared_info == shared_info_page)
+		return;
+
 	if (!shared_info_page)
 		shared_info_page = (struct shared_info *)
 			get_zeroed_page(GFP_KERNEL);
@@ -161,11 +165,11 @@ void __ref xen_hvm_init_shared_info(void)
 		per_cpu(xen_vcpu, cpu) = &HYPERVISOR_shared_info->vcpu_info[cpu];
 	}
 }
+core_initcall(xen_hvm_init_shared_info);
 
-static int __init xen_hvm_guest_init(void)
+int __init xen_guest_init(void)
 {
 	xen_hvm_init_shared_info();
 	return 0;
 }
-
-core_initcall(xen_hvm_guest_init);
+EXPORT_SYMBOL(xen_guest_init);
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 1f92865..0bad7b5 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1420,4 +1420,12 @@ 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(xen_guest_init);
 #endif
diff --git a/drivers/tty/hvc/hvc_xen.c b/drivers/tty/hvc/hvc_xen.c
index 3ae96a9..52a98ff 100644
--- a/drivers/tty/hvc/hvc_xen.c
+++ b/drivers/tty/hvc/hvc_xen.c
@@ -578,6 +578,9 @@ static int xen_cons_init(void)
 	if (!xen_domain())
 		return 0;
 
+	/* retrieve xen infos  */
+	xen_guest_init();
+
 	if (xen_initial_domain())
 		ops = &dom0_hvc_ops;
 	else {
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