[Xen-devel] [PATCH] xenstored: allow guests to reintroduce themselves

[Olaf Hering <olaf@xxxxxxxxx>]

# HG changeset patch
# User Olaf Hering <olaf@xxxxxxxxx>
# Date 1312202176 -7200
# Node ID edb96c34f4a638e8ba97933b6bd76ff72836353e
# Parent  0f36c2eec2e1576b4db6538b5f22d625587c1a15
xenstored: allow guests to reintroduce themselves

During kexec all old watches have to be removed, otherwise the new
kernel will receive unexpected events. Allow a guest to introduce itself
and cleanup all of its watches.

Signed-off-by: Olaf Hering <olaf@xxxxxxxxx>

diff -r 0f36c2eec2e1 -r edb96c34f4a6 tools/xenstore/xenstored_domain.c
--- a/tools/xenstore/xenstored_domain.c
+++ b/tools/xenstore/xenstored_domain.c
@@ -315,7 +315,7 @@ void do_introduce(struct connection *con
 {
        struct domain *domain;
        char *vec[3];
-       unsigned int domid;
+       unsigned int domid, target;
        unsigned long mfn;
        evtchn_port_t port;
        int rc;
@@ -326,7 +326,7 @@ void do_introduce(struct connection *con
                return;
        }
 
-       if (conn->id != 0 || !conn->can_write) {
+       if (!conn->can_write) {
                send_error(conn, EACCES);
                return;
        }
@@ -340,19 +340,26 @@ void do_introduce(struct connection *con
                send_error(conn, EINVAL);
                return;
        }
+       /* Allow guest to reset all watches */
+       if (domid != DOMID_SELF && conn->id != 0) {
+               send_error(conn, EACCES);
+               return;
+       }
 
-       domain = find_domain_by_domid(domid);
+       target = domid == DOMID_SELF ? conn->id : domid;
+
+       domain = find_domain_by_domid(target);
 
        if (domain == NULL) {
                interface = xc_map_foreign_range(
-                       *xc_handle, domid,
+                       *xc_handle, target,
                        getpagesize(), PROT_READ|PROT_WRITE, mfn);
                if (!interface) {
                        send_error(conn, errno);
                        return;
                }
                /* Hang domain off "in" until we're finished. */
-               domain = new_domain(in, domid, port);
+               domain = new_domain(in, target, port);
                if (!domain) {
                        munmap(interface, getpagesize());
                        send_error(conn, errno);
@@ -365,11 +372,11 @@ void do_introduce(struct connection *con
                talloc_steal(domain->conn, domain);
 
                fire_watches(NULL, "@introduceDomain", false);
-       } else if ((domain->mfn == mfn) && (domain->conn != conn)) {
+       } else if ((domain->mfn == mfn) && ((domain->conn != conn) || domid == 
DOMID_SELF)) {
                /* Use XS_INTRODUCE for recreating the xenbus event-channel. */
                if (domain->port)
                        xc_evtchn_unbind(xce_handle, domain->port);
-               rc = xc_evtchn_bind_interdomain(xce_handle, domid, port);
+               rc = xc_evtchn_bind_interdomain(xce_handle, target, port);
                domain->port = (rc == -1) ? 0 : rc;
                domain->remote_port = port;
        } else {

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