xen/arm: compile and run xenbus

bind_evtchn_to_irqhandler can legitimately return 0 (irq 0): it is not
an error.

If Linux is running as an HVM domain and is running as Dom0, use
xenstored_local_init to initialize the xenstore page and event channel.

Changes in v4:
- do not xs_reset_watches on dom0.

Changes in v2:
- refactor xenbus_init.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
[v5: Fixed case switch indentations]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

3 files changed, 41 insertions, 16 deletions

diff --git a/drivers/xen/xenbus/xenbus_comms.c b/drivers/xen/xenbus/xenbus_comms.c
index 52fe7ad07666..c5aa55c5d371 100644
--- a/drivers/xen/xenbus/xenbus_comms.c
+++ b/drivers/xen/xenbus/xenbus_comms.c
@@ -224,7 +224,7 @@ int xb_init_comms(void)
                 int err;
                 err = bind_evtchn_to_irqhandler(xen_store_evtchn, wake_waiting,
                                                 0, "xenbus", &xb_waitq);
-                if (err <= 0) {
+                if (err < 0) {
                         printk(KERN_ERR "XENBUS request irq failed %i\n", err);
                         return err;
                 }
diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c
index 91d3d6544a7b..038b71dbf03c 100644
--- a/drivers/xen/xenbus/xenbus_probe.c
+++ b/drivers/xen/xenbus/xenbus_probe.c
@@ -719,17 +719,47 @@ static int __init xenstored_local_init(void)
         return err;
 }
 
+enum xenstore_init {
+        UNKNOWN,
+        PV,
+        HVM,
+        LOCAL,
+};
 static int __init xenbus_init(void)
 {
         int err = 0;
+        enum xenstore_init usage = UNKNOWN;
+        uint64_t v = 0;
 
         if (!xen_domain())
                 return -ENODEV;
 
         xenbus_ring_ops_init();
 
-        if (xen_hvm_domain()) {
-                uint64_t v = 0;
+        if (xen_pv_domain())
+                usage = PV;
+        if (xen_hvm_domain())
+                usage = HVM;
+        if (xen_hvm_domain() && xen_initial_domain())
+                usage = LOCAL;
+        if (xen_pv_domain() && !xen_start_info->store_evtchn)
+                usage = LOCAL;
+        if (xen_pv_domain() && xen_start_info->store_evtchn)
+                xenstored_ready = 1;
+
+        switch (usage) {
+        case LOCAL:
+                err = xenstored_local_init();
+                if (err)
+                        goto out_error;
+                xen_store_interface = mfn_to_virt(xen_store_mfn);
+                break;
+        case PV:
+                xen_store_evtchn = xen_start_info->store_evtchn;
+                xen_store_mfn = xen_start_info->store_mfn;
+                xen_store_interface = mfn_to_virt(xen_store_mfn);
+                break;
+        case HVM:
                 err = hvm_get_parameter(HVM_PARAM_STORE_EVTCHN, &v);
                 if (err)
                         goto out_error;
@@ -738,18 +768,12 @@ static int __init xenbus_init(void)
                 if (err)
                         goto out_error;
                 xen_store_mfn = (unsigned long)v;
-                xen_store_interface = ioremap(xen_store_mfn << PAGE_SHIFT, PAGE_SIZE);
-        } else {
-                xen_store_evtchn = xen_start_info->store_evtchn;
-                xen_store_mfn = xen_start_info->store_mfn;
-                if (xen_store_evtchn)
-                        xenstored_ready = 1;
-                else {
-                        err = xenstored_local_init();
-                        if (err)
-                                goto out_error;
-                }
-                xen_store_interface = mfn_to_virt(xen_store_mfn);
+                xen_store_interface =
+                        ioremap(xen_store_mfn << PAGE_SHIFT, PAGE_SIZE);
+                break;
+        default:
+                pr_warn("Xenstore state unknown\n");
+                break;
         }
 
         /* Initialize the interface to xenstore. */
diff --git a/drivers/xen/xenbus/xenbus_xs.c b/drivers/xen/xenbus/xenbus_xs.c
index bce15cf4a8df..131dec04794e 100644
--- a/drivers/xen/xenbus/xenbus_xs.c
+++ b/drivers/xen/xenbus/xenbus_xs.c
@@ -44,6 +44,7 @@
 #include <linux/rwsem.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
+#include <asm/xen/hypervisor.h>
 #include <xen/xenbus.h>
 #include <xen/xen.h>
 #include "xenbus_comms.h"
@@ -622,7 +623,7 @@ static void xs_reset_watches(void)
 {
         int err, supported = 0;
 
-        if (!xen_hvm_domain())
+        if (!xen_hvm_domain() || xen_initial_domain())
                 return;
 
         err = xenbus_scanf(XBT_NIL, "control",