p2m: query/modify p2mt with p2m_lock held

Query and update the p2mt in set_mmio_p2m_entry, clear_mmio_p2m_entry
and set_shared_p2m_entry with the p2m_lock held.

Signed-off-by: Olaf Hering <olaf@aepfle.de>
Acked-by: Tim Deegan <tim@xen.org>
Committed-by: Tim Deegan <tim@xen.org>

xen/arch/x86/mm/p2m.c

@@ -583,9 +583,11 @@ set_mmio_p2m_entry(struct domain *d, unsigned long gfn, mfn_t mfn)
     if ( !paging_mode_translate(d) )
         return 0;
 
+    p2m_lock(p2m);
     omfn = gfn_to_mfn_query(d, gfn, &ot);
     if ( p2m_is_grant(ot) )
     {
+        p2m_unlock(p2m);
         domain_crash(d);
         return 0;
     }
@@ -596,7 +598,6 @@ set_mmio_p2m_entry(struct domain *d, unsigned long gfn, mfn_t mfn)
     }
 
     P2M_DEBUG("set mmio %lx %lx\n", gfn, mfn_x(mfn));
-    p2m_lock(p2m);
     rc = set_p2m_entry(p2m, gfn, mfn, 0, p2m_mmio_direct, p2m->default_access);
     audit_p2m(p2m, 1);
     p2m_unlock(p2m);
@@ -618,18 +619,20 @@ clear_mmio_p2m_entry(struct domain *d, unsigned long gfn)
     if ( !paging_mode_translate(d) )
         return 0;
 
-    mfn = gfn_to_mfn(d, gfn, &t);
+    p2m_lock(p2m);
+    mfn = gfn_to_mfn_query(d, gfn, &t);
 
     /* Do not use mfn_valid() here as it will usually fail for MMIO pages. */
     if ( (INVALID_MFN == mfn_x(mfn)) || (t != p2m_mmio_direct) )
     {
         gdprintk(XENLOG_ERR,
             "clear_mmio_p2m_entry: gfn_to_mfn failed! gfn=%08lx\n", gfn);
-        return 0;
+        goto out;
     }
-    p2m_lock(p2m);
     rc = set_p2m_entry(p2m, gfn, _mfn(INVALID_MFN), 0, p2m_invalid, p2m->default_access);
     audit_p2m(p2m, 1);
+
+out:
     p2m_unlock(p2m);
 
     return rc;
@@ -646,6 +649,7 @@ set_shared_p2m_entry(struct domain *d, unsigned long gfn, mfn_t mfn)
     if ( !paging_mode_translate(p2m->domain) )
         return 0;
 
+    p2m_lock(p2m);
     omfn = gfn_to_mfn_query(p2m->domain, gfn, &ot);
     /* At the moment we only allow p2m change if gfn has already been made
      * sharable first */
@@ -655,7 +659,6 @@ set_shared_p2m_entry(struct domain *d, unsigned long gfn, mfn_t mfn)
     set_gpfn_from_mfn(mfn_x(omfn), INVALID_M2P_ENTRY);
 
     P2M_DEBUG("set shared %lx %lx\n", gfn, mfn_x(mfn));
-    p2m_lock(p2m);
     rc = set_p2m_entry(p2m, gfn, mfn, 0, p2m_ram_shared, p2m->default_access);
     p2m_unlock(p2m);
     if ( 0 == rc )