[PATCH v5 4/7] xen/arm: configure dom0less domain for enabling xenstore after boot

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

From: Luca Miccio <lucmiccio@xxxxxxxxx>

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@xxxxxxxxx>
Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxx>
CC: Julien Grall <julien@xxxxxxx>
CC: Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>
CC: Bertrand Marquis <bertrand.marquis@xxxxxxx>
CC: Jan Beulich <jbeulich@xxxxxxxx>

---
I removed Bertrand's reviewed-by due to merging this patch with "xen:
export evtchn_alloc_unbound"

Changes in v5:
- merge with "xen: export evtchn_alloc_unbound"
- __must_check

Changes in v3:
- use evtchn_alloc_unbound

Changes in v2:
- set HVM_PARAM_STORE_PFN to ~0ULL at domain creation
- in alloc_xenstore_evtchn do not call _evtchn_alloc_unbound

xen: export evtchn_alloc_unbound

It will be used during dom0less domains construction.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxx>
---
 xen/arch/arm/domain_build.c | 37 +++++++++++++++++++++++++++++++++++++
 xen/common/event_channel.c  |  2 +-
 xen/include/xen/event.h     |  3 +++
 3 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index a877ccf585..249efbf804 100644
--- a/xen/arch/arm/domain_build.c
+++ b/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>
@@ -2809,6 +2810,8 @@ 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;
@@ -2883,6 +2886,13 @@ 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;
@@ -3149,6 +3159,25 @@ 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)
 {
@@ -3213,6 +3242,14 @@ static int __init construct_domU(struct domain *d,
     if ( rc < 0 )
         return rc;
 
+    if ( kinfo.dom0less_enhanced )
+    {
+        rc = alloc_xenstore_evtchn(d);
+        if ( rc < 0 )
+            return rc;
+        d->arch.hvm.params[HVM_PARAM_STORE_PFN] = ~0ULL;
+    }
+
     return rc;
 }
 
diff --git a/xen/common/event_channel.c b/xen/common/event_channel.c
index ffb042a241..2f6a89f52d 100644
--- a/xen/common/event_channel.c
+++ b/xen/common/event_channel.c
@@ -289,7 +289,7 @@ 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;
diff --git a/xen/include/xen/event.h b/xen/include/xen/event.h
index 21c95e14fd..f3021fe304 100644
--- a/xen/include/xen/event.h
+++ b/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);
 
-- 
2.25.1