x86/ioreq server: synchronously reset outstanding p2m_ioreq_server entries when an...

After an ioreq server has unmapped, the remaining p2m_ioreq_server
entries need to be reset back to p2m_ram_rw. This patch does this
synchronously by iterating the p2m table.

The synchronous resetting is necessary because we need to guarantee
the p2m table is clean before another ioreq server is mapped. And
since the sweeping of p2m table could be time consuming, it is done
with hypercall continuation.

Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
Reviewed-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: George Dunlap <george.dunlap@citrix.com>

diff --git a/xen/arch/x86/hvm/dm.c b/xen/arch/x86/hvm/dm.c
index 7e0da8103353d7a686ee302b60db32f57b7a8562..d72b7bd8357e9d7f37be4f3ea0d1e6eac1ab4540 100644 (file)
--- a/xen/arch/x86/hvm/dm.c
+++ b/xen/arch/x86/hvm/dm.c
@@ -384,15 +384,50 @@ static int dm_op(domid_t domid,
 
     case XEN_DMOP_map_mem_type_to_ioreq_server:
     {
-        const struct xen_dm_op_map_mem_type_to_ioreq_server *data =
+        struct xen_dm_op_map_mem_type_to_ioreq_server *data =
             &op.u.map_mem_type_to_ioreq_server;
+        unsigned long first_gfn = data->opaque;
+
+        const_op = false;
 
         rc = -EOPNOTSUPP;
         if ( !hap_enabled(d) )
             break;
 
-        rc = hvm_map_mem_type_to_ioreq_server(d, data->id,
-                                              data->type, data->flags);
+        if ( first_gfn == 0 )
+            rc = hvm_map_mem_type_to_ioreq_server(d, data->id,
+                                                  data->type, data->flags);
+        else
+            rc = 0;
+
+        /*
+         * Iterate p2m table when an ioreq server unmaps from p2m_ioreq_server,
+         * and reset the remaining p2m_ioreq_server entries back to p2m_ram_rw.
+         */
+        if ( rc == 0 && data->flags == 0 )
+        {
+            struct p2m_domain *p2m = p2m_get_hostp2m(d);
+
+            while ( read_atomic(&p2m->ioreq.entry_count) &&
+                    first_gfn <= p2m->max_mapped_pfn )
+            {
+                /* Iterate p2m table for 256 gfns each time. */
+                p2m_finish_type_change(d, _gfn(first_gfn), 256,
+                                       p2m_ioreq_server, p2m_ram_rw);
+
+                first_gfn += 256;
+
+                /* Check for continuation if it's not the last iteration. */
+                if ( first_gfn <= p2m->max_mapped_pfn &&
+                     hypercall_preempt_check() )
+                {
+                    rc = -ERESTART;
+                    data->opaque = first_gfn;
+                    break;
+                }
+            }
+        }
+
         break;
     }
 

diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index 4169d18ddadfa02c57f13af65dcc009efe8d5af8..1d57e5c0550bc23fedb4e9a0c49e7a0b101726a3 100644 (file)
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -1011,6 +1011,35 @@ void p2m_change_type_range(struct domain *d,
     p2m_unlock(p2m);
 }
 
+/* Synchronously modify the p2m type for a range of gfns from ot to nt. */
+void p2m_finish_type_change(struct domain *d,
+                            gfn_t first_gfn, unsigned long max_nr,
+                            p2m_type_t ot, p2m_type_t nt)
+{
+    struct p2m_domain *p2m = p2m_get_hostp2m(d);
+    p2m_type_t t;
+    unsigned long gfn = gfn_x(first_gfn);
+    unsigned long last_gfn = gfn + max_nr - 1;
+
+    ASSERT(ot != nt);
+    ASSERT(p2m_is_changeable(ot) && p2m_is_changeable(nt));
+
+    p2m_lock(p2m);
+
+    last_gfn = min(last_gfn, p2m->max_mapped_pfn);
+    while ( gfn <= last_gfn )
+    {
+        get_gfn_query_unlocked(d, gfn, &t);
+
+        if ( t == ot )
+            p2m_change_type_one(d, gfn, t, nt);
+
+        gfn++;
+    }
+
+    p2m_unlock(p2m);
+}
+
 /*
  * Returns:
  *    0              for success

diff --git a/xen/include/asm-x86/p2m.h b/xen/include/asm-x86/p2m.h
index f27b3a6844c3f0089106ba0d647b45e3435bbccd..7574a9b66ebd6c6bc70b9d509ac941ee50ee974b 100644 (file)
--- a/xen/include/asm-x86/p2m.h
+++ b/xen/include/asm-x86/p2m.h
@@ -606,6 +606,12 @@ void p2m_change_type_range(struct domain *d,
 int p2m_change_type_one(struct domain *d, unsigned long gfn,
                         p2m_type_t ot, p2m_type_t nt);
 
+/* Synchronously change the p2m type for a range of gfns */
+void p2m_finish_type_change(struct domain *d,
+                            gfn_t first_gfn,
+                            unsigned long max_nr,
+                            p2m_type_t ot, p2m_type_t nt);
+
 /* Report a change affecting memory types. */
 void p2m_memory_type_changed(struct domain *d);