[PATCH v2 10/24] hw/xen: populate store frontend nodes with XenStore PFN/port

[David Woodhouse <dwmw2@infradead.org>]

From: David Woodhouse <dwmw@amazon.co.uk>

This is kind of redundant since without being able to get these through
some other method (HVMOP_get_param) the guest wouldn't be able to access
XenStore in order to find them. But Xen populates them, and it does
allow guests to *rebind* to the event channel port after a reset.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
---
 hw/i386/kvm/xen_xenstore.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/hw/i386/kvm/xen_xenstore.c b/hw/i386/kvm/xen_xenstore.c
index ef8aaa4c42..61692d4489 100644
--- a/hw/i386/kvm/xen_xenstore.c
+++ b/hw/i386/kvm/xen_xenstore.c
@@ -1434,6 +1434,7 @@ static void alloc_guest_port(XenXenstoreState *s)
 int xen_xenstore_reset(void)
 {
     XenXenstoreState *s = xen_xenstore_singleton;
+    GList *perms;
     int err;
 
     if (!s) {
@@ -1461,6 +1462,16 @@ int xen_xenstore_reset(void)
     }
     s->be_port = err;
 
+    /* Create frontend store nodes */
+    perms = g_list_append(NULL, xs_perm_as_string(XS_PERM_NONE, DOMID_QEMU));
+    perms = g_list_append(perms, xs_perm_as_string(XS_PERM_READ, xen_domid));
+
+    relpath_printf(s, perms, "store/port", "%u", s->guest_port);
+    relpath_printf(s, perms, "store/ring-ref", "%lu",
+                   XEN_SPECIAL_PFN(XENSTORE));
+
+    g_list_free_full(perms, g_free);
+
     /*
      * We don't actually access the guest's page through the grant, because
      * this isn't real Xen, and we can just use the page we gave it in the
-- 
2.40.1