xen/arm: configure dom0less domain for enabling xenstore after boot

Export evtchn_alloc_unbound and make it __must_check.

If "xen,enhanced" is enabled, then add to dom0less domains:

- the hypervisor node in device tree
- the xenstore event channel

The xenstore event channel is also used for the first notification to
let the guest know that xenstore has become available.

Signed-off-by: Luca Miccio <lucmiccio@gmail.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
Reviewed-by: Bertrand Marquis <bertrand.marquis@arm.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
CC: Julien Grall <julien@xen.org>
CC: Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>
CC: Bertrand Marquis <bertrand.marquis@arm.com>

xen/arch/arm/domain_build.c

@@ -27,6 +27,7 @@
 #include <asm/setup.h>
 #include <asm/cpufeature.h>
 #include <asm/domain_build.h>
+#include <xen/event.h>
 
 #include <xen/irq.h>
 #include <xen/grant_table.h>
@@ -2813,6 +2814,8 @@ static int __init prepare_dtb_domU(struct domain *d, struct kernel_info *kinfo)
     int ret;
 
     kinfo->phandle_gic = GUEST_PHANDLE_GIC;
+    kinfo->gnttab_start = GUEST_GNTTAB_BASE;
+    kinfo->gnttab_size = GUEST_GNTTAB_SIZE;
 
     addrcells = GUEST_ROOT_ADDRESS_CELLS;
     sizecells = GUEST_ROOT_SIZE_CELLS;
@@ -2887,6 +2890,13 @@ static int __init prepare_dtb_domU(struct domain *d, struct kernel_info *kinfo)
             goto err;
     }
 
+    if ( kinfo->dom0less_enhanced )
+    {
+        ret = make_hypervisor_node(d, kinfo, addrcells, sizecells);
+        if ( ret )
+            goto err;
+    }
+
     ret = fdt_end_node(kinfo->fdt);
     if ( ret < 0 )
         goto err;
@@ -3153,6 +3163,25 @@ static int __init construct_domain(struct domain *d, struct kernel_info *kinfo)
     return 0;
 }
 
+static int __init alloc_xenstore_evtchn(struct domain *d)
+{
+    evtchn_alloc_unbound_t alloc;
+    int rc;
+
+    alloc.dom = d->domain_id;
+    alloc.remote_dom = hardware_domain->domain_id;
+    rc = evtchn_alloc_unbound(&alloc);
+    if ( rc )
+    {
+        printk("Failed allocating event channel for domain\n");
+        return rc;
+    }
+
+    d->arch.hvm.params[HVM_PARAM_STORE_EVTCHN] = alloc.port;
+
+    return 0;
+}
+
 static int __init construct_domU(struct domain *d,
                                  const struct dt_device_node *node)
 {
@@ -3222,6 +3251,15 @@ static int __init construct_domU(struct domain *d,
     if ( rc < 0 )
         return rc;
 
+    if ( kinfo.dom0less_enhanced )
+    {
+        ASSERT(hardware_domain);
+        rc = alloc_xenstore_evtchn(d);
+        if ( rc < 0 )
+            return rc;
+        d->arch.hvm.params[HVM_PARAM_STORE_PFN] = ~0ULL;
+    }
+
     return rc;
 }
 

xen/common/event_channel.c

@@ -290,7 +290,7 @@ void evtchn_free(struct domain *d, struct evtchn *chn)
     xsm_evtchn_close_post(chn);
 }
 
-static int evtchn_alloc_unbound(evtchn_alloc_unbound_t *alloc)
+int evtchn_alloc_unbound(evtchn_alloc_unbound_t *alloc)
 {
     struct evtchn *chn;
     struct domain *d;

xen/include/xen/event.h

@@ -71,6 +71,9 @@ void evtchn_free(struct domain *d, struct evtchn *chn);
 /* Allocate a specific event channel port. */
 int evtchn_allocate_port(struct domain *d, unsigned int port);
 
+/* Allocate a new event channel */
+int __must_check evtchn_alloc_unbound(evtchn_alloc_unbound_t *alloc);
+
 /* Unmask a local event-channel port. */
 int evtchn_unmask(unsigned int port);