gnttab: don't flush the TLB on grant ops for auto-translated guests

For auto-translated guests the p2m code will do the necessary TLB
flushes, so there's no need to perform any TLB flushes in generic
grant table code.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Tim Deegan <tim@xen.org>

diff --git a/xen/common/grant_table.c b/xen/common/grant_table.c
index 778bdb76720b26ef2d8b598b37f58189e6205164..2c93d9cc38a1d2da5217ffbb8fe156471307225f 100644 (file)
--- a/xen/common/grant_table.c
+++ b/xen/common/grant_table.c
@@ -147,6 +147,12 @@ struct active_grant_entry {
 #define active_entry(t, e) \
     ((t)->active[(e)/ACGNT_PER_PAGE][(e)%ACGNT_PER_PAGE])
 
+static inline void gnttab_flush_tlb(const struct domain *d)
+{
+    if ( !paging_mode_external(d) )
+        flush_tlb_mask(d->domain_dirty_cpumask);
+}
+
 static inline unsigned int
 num_act_frames_from_sha_frames(const unsigned int num)
 {
@@ -1096,7 +1102,7 @@ gnttab_unmap_grant_ref(
             guest_handle_add_offset(uop, 1);
         }
 
-        flush_tlb_mask(current->domain->domain_dirty_cpumask);
+        gnttab_flush_tlb(current->domain);
 
         for ( i = 0; i < partial_done; i++ )
             __gnttab_unmap_common_complete(&(common[i]));
@@ -1111,7 +1117,7 @@ gnttab_unmap_grant_ref(
     return 0;
 
 fault:
-    flush_tlb_mask(current->domain->domain_dirty_cpumask);
+    gnttab_flush_tlb(current->domain);
 
     for ( i = 0; i < partial_done; i++ )
         __gnttab_unmap_common_complete(&(common[i]));
@@ -1159,7 +1165,7 @@ gnttab_unmap_and_replace(
             guest_handle_add_offset(uop, 1);
         }
         
-        flush_tlb_mask(current->domain->domain_dirty_cpumask);
+        gnttab_flush_tlb(current->domain);
         
         for ( i = 0; i < partial_done; i++ )
             __gnttab_unmap_common_complete(&(common[i]));
@@ -1174,7 +1180,7 @@ gnttab_unmap_and_replace(
     return 0;
 
 fault:
-    flush_tlb_mask(current->domain->domain_dirty_cpumask);
+    gnttab_flush_tlb(current->domain);
 
     for ( i = 0; i < partial_done; i++ )
         __gnttab_unmap_common_complete(&(common[i]));
@@ -1566,7 +1572,7 @@ gnttab_transfer(
         }
 
         guest_physmap_remove_page(d, gop.mfn, mfn, 0);
-        flush_tlb_mask(d->domain_dirty_cpumask);
+        gnttab_flush_tlb(d);
 
         /* Find the target domain. */
         if ( unlikely((e = rcu_lock_domain_by_id(gop.domid)) == NULL) )