hvm: Fail attempts to add pages to guest pseudophys memory map above

4GB when running with AMD NPT on PAE host.
From: Wei Huang <Wei.Huang2@amd.com>
Signed-off-by: Keir Fraser <keir@xensource.com>

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index dcdcceb8415ab50cf7446af64fd13f94ceb7ea0a..89a90f8d7323b02bc4b3827b8fd21be95a15094e 100644 (file)
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -53,10 +53,11 @@
 /*
  * Xen command-line option to allow/disallow hardware-assisted paging.
  * Since the phys-to-machine table of AMD NPT is in host format, 32-bit Xen
- * could only support guests using NPT with up to a 4GB memory map. Therefore
- * we only allow HAP by default on 64-bit Xen.
+ * can only support guests using NPT with up to a 4GB memory map. Therefore
+ * we disallow HAP by default on PAE Xen (by default we want to support an
+ * 8GB pseudophysical memory map for HVM guests on a PAE host).
  */
-static int opt_hap_permitted = (BITS_PER_LONG == 8);
+static int opt_hap_permitted = (CONFIG_PAGING_LEVELS != 3);
 boolean_param("hap", opt_hap_permitted);
 
 int hvm_enabled __read_mostly;

diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index 0dfdaaceb55bef0431fa2a48f97116e3e19a4f8b..ae158fdac5cc7f68b9e0874d6fd9aa62f508ef73 100644 (file)
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -219,15 +219,17 @@ set_p2m_entry(struct domain *d, unsigned long gfn, mfn_t mfn, p2m_type_t p2mt)
         goto out;
 #endif
 #if CONFIG_PAGING_LEVELS >= 3
-    // When using PAE Xen, we only allow 33 bits of pseudo-physical
-    // address in translated guests (i.e. 8 GBytes).  This restriction
-    // comes from wanting to map the P2M table into the 16MB RO_MPT hole
-    // in Xen's address space for translated PV guests.
-    //
+    /*
+     * When using PAE Xen, we only allow 33 bits of pseudo-physical
+     * address in translated guests (i.e. 8 GBytes).  This restriction
+     * comes from wanting to map the P2M table into the 16MB RO_MPT hole
+     * in Xen's address space for translated PV guests.
+     * When using AMD's NPT on PAE Xen, we are restricted to 4GB.
+     */
     if ( !p2m_next_level(d, &table_mfn, &table, &gfn_remainder, gfn,
                          L3_PAGETABLE_SHIFT - PAGE_SHIFT,
-                         (CONFIG_PAGING_LEVELS == 3
-                          ? 8
+                         ((CONFIG_PAGING_LEVELS == 3)
+                          ? (hvm_funcs.hap_supported ? 4 : 8)
                           : L3_PAGETABLE_ENTRIES),
                          PGT_l2_page_table) )
         goto out;
@@ -686,16 +688,26 @@ guest_physmap_remove_page(struct domain *d, unsigned long gfn,
     p2m_unlock(d);
 }
 
-void
+int
 guest_physmap_add_entry(struct domain *d, unsigned long gfn,
                         unsigned long mfn, p2m_type_t t)
 {
     unsigned long ogfn;
     p2m_type_t ot;
     mfn_t omfn;
+    int rc = 0;
 
     if ( !paging_mode_translate(d) )
-        return;
+        return -EINVAL;
+
+#if CONFIG_PAGING_LEVELS == 3
+    /* 32bit PAE nested paging does not support over 4GB guest due to 
+     * hardware translation limit. This limitation is checked by comparing
+     * gfn with 0xfffffUL.
+     */
+    if ( paging_mode_hap(d) && (gfn > 0xfffffUL) )
+        return -EINVAL;
+#endif
 
     p2m_lock(d);
     audit_p2m(d);
@@ -735,18 +747,22 @@ guest_physmap_add_entry(struct domain *d, unsigned long gfn,
 
     if ( mfn_valid(_mfn(mfn)) ) 
     {
-        set_p2m_entry(d, gfn, _mfn(mfn), t);
+        if ( !set_p2m_entry(d, gfn, _mfn(mfn), t) )
+            rc = -EINVAL;
         set_gpfn_from_mfn(mfn, gfn);
     }
     else
     {
         gdprintk(XENLOG_WARNING, "Adding bad mfn to p2m map (%#lx -> %#lx)\n",
                  gfn, mfn);
-        set_p2m_entry(d, gfn, _mfn(INVALID_MFN), p2m_invalid);
+        if ( !set_p2m_entry(d, gfn, _mfn(INVALID_MFN), p2m_invalid) )
+            rc = -EINVAL;
     }
 
     audit_p2m(d);
     p2m_unlock(d);
+
+    return rc;
 }
 
 /* Walk the whole p2m table, changing any entries of the old type

diff --git a/xen/common/memory.c b/xen/common/memory.c
index 783de29749fb689d41b028d0dff1c998cef512e6..704497944af79f30ae1879c3cca29027781617d4 100644 (file)
--- a/xen/common/memory.c
+++ b/xen/common/memory.c
@@ -131,7 +131,8 @@ static void populate_physmap(struct memop_args *a)
         if ( unlikely(paging_mode_translate(d)) )
         {
             for ( j = 0; j < (1 << a->extent_order); j++ )
-                guest_physmap_add_page(d, gpfn + j, mfn + j);
+                if ( guest_physmap_add_page(d, gpfn + j, mfn + j) )
+                    goto out;
         }
         else
         {
@@ -445,8 +446,9 @@ static long memory_exchange(XEN_GUEST_HANDLE(xen_memory_exchange_t) arg)
             mfn = page_to_mfn(page);
             if ( unlikely(paging_mode_translate(d)) )
             {
+                /* Ignore failure here. There's nothing we can do. */
                 for ( k = 0; k < (1UL << exch.out.extent_order); k++ )
-                    guest_physmap_add_page(d, gpfn + k, mfn + k);
+                    (void)guest_physmap_add_page(d, gpfn + k, mfn + k);
             }
             else
             {

diff --git a/xen/include/asm-x86/p2m.h b/xen/include/asm-x86/p2m.h
index c2801694281bd891d7b281410fe34cbcb81737f6..38a9cec7bdb6077580d105f5f9aa082609fa36e8 100644 (file)
--- a/xen/include/asm-x86/p2m.h
+++ b/xen/include/asm-x86/p2m.h
@@ -201,14 +201,17 @@ int p2m_alloc_table(struct domain *d,
 void p2m_teardown(struct domain *d);
 
 /* Add a page to a domain's p2m table */
-void guest_physmap_add_entry(struct domain *d, unsigned long gfn,
+int guest_physmap_add_entry(struct domain *d, unsigned long gfn,
                              unsigned long mfn, p2m_type_t t);
 
-/* Untyped version for RAM only, for compatibility */
-static inline void guest_physmap_add_page(struct domain *d, unsigned long gfn,
-                                          unsigned long mfn)
+/* Untyped version for RAM only, for compatibility 
+ *
+ * Return 0 for success
+ */
+static inline int guest_physmap_add_page(struct domain *d, unsigned long gfn,
+                                         unsigned long mfn)
 {
-    guest_physmap_add_entry(d, gfn, mfn, p2m_ram_rw);
+    return guest_physmap_add_entry(d, gfn, mfn, p2m_ram_rw);
 }
 
 /* Remove a page from a domain's p2m table */