x86/P2M: introduce p2m_{add,remove}_page()

Rename guest_physmap_add_entry() to p2m_add_page(); make
guest_physmap_remove_page() a trivial wrapper around p2m_remove_page().
This way callers can use suitable pairs of functions (previously
violated by hvm/grant_table.c).

In HVM-specific code further avoid going through the guest_physmap_*()
layer, and instead use the two new/renamed functions directly.

Ultimately the goal is to have guest_physmap_...() functions cover all
types of guests, but p2m_...() dealing only with translated ones.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Paul Durrant <paul@xen.org>
Reviewed-by: George Dunlap <george.dunlap@citrix.com>

xen/arch/x86/hvm/dom0_build.c

@@ -173,8 +173,7 @@ static int __init pvh_populate_memory_range(struct domain *d,
             continue;
         }
 
-        rc = guest_physmap_add_page(d, _gfn(start), page_to_mfn(page),
-                                    order);
+        rc = p2m_add_page(d, _gfn(start), page_to_mfn(page), order, p2m_ram_rw);
         if ( rc != 0 )
         {
             printk("Failed to populate memory: [%#lx,%#lx): %d\n",

xen/arch/x86/hvm/grant_table.c

@@ -39,9 +39,8 @@ int create_grant_p2m_mapping(uint64_t addr, mfn_t frame,
         p2mt = p2m_grant_map_ro;
     else
         p2mt = p2m_grant_map_rw;
-    rc = guest_physmap_add_entry(current->domain,
-                                 _gfn(addr >> PAGE_SHIFT),
-                                 frame, PAGE_ORDER_4K, p2mt);
+    rc = p2m_add_page(current->domain, _gfn(addr >> PAGE_SHIFT),
+                      frame, PAGE_ORDER_4K, p2mt);
     if ( rc )
         return GNTST_general_error;
     else
@@ -68,7 +67,7 @@ int replace_grant_p2m_mapping(uint64_t addr, mfn_t frame,
                  type, mfn_x(old_mfn), mfn_x(frame));
         return GNTST_general_error;
     }
-    if ( guest_physmap_remove_page(d, _gfn(gfn), frame, PAGE_ORDER_4K) )
+    if ( p2m_remove_page(d, _gfn(gfn), frame, PAGE_ORDER_4K) )
     {
         put_gfn(d, gfn);
         return GNTST_general_error;

xen/arch/x86/hvm/ioreq.c

@@ -188,8 +188,7 @@ static void hvm_remove_ioreq_gfn(struct ioreq_server *s, bool buf)
     if ( gfn_eq(iorp->gfn, INVALID_GFN) )
         return;
 
-    if ( guest_physmap_remove_page(d, iorp->gfn,
-                                   page_to_mfn(iorp->page), 0) )
+    if ( p2m_remove_page(d, iorp->gfn, page_to_mfn(iorp->page), 0) )
         domain_crash(d);
     clear_page(iorp->va);
 }
@@ -205,8 +204,7 @@ static int hvm_add_ioreq_gfn(struct ioreq_server *s, bool buf)
 
     clear_page(iorp->va);
 
-    rc = guest_physmap_add_page(d, iorp->gfn,
-                                page_to_mfn(iorp->page), 0);
+    rc = p2m_add_page(d, iorp->gfn, page_to_mfn(iorp->page), 0, p2m_ram_rw);
     if ( rc == 0 )
         paging_mark_pfn_dirty(d, _pfn(gfn_x(iorp->gfn)));
 

xen/arch/x86/include/asm/p2m.h

@@ -577,10 +577,11 @@ int p2m_alloc_table(struct p2m_domain *p2m);
 void p2m_teardown(struct p2m_domain *p2m);
 void p2m_final_teardown(struct domain *d);
 
-/* Add a page to a domain's p2m table */
-int guest_physmap_add_entry(struct domain *d, gfn_t gfn,
-                            mfn_t mfn, unsigned int page_order,
-                            p2m_type_t t);
+/* Add/remove a page to/from a domain's p2m table. */
+int p2m_add_page(struct domain *d, gfn_t gfn, mfn_t mfn,
+                 unsigned int page_order, p2m_type_t t);
+int p2m_remove_page(struct domain *d, gfn_t gfn, mfn_t mfn,
+                    unsigned int page_order);
 
 /* Untyped version for RAM only, for compatibility and PV. */
 int __must_check guest_physmap_add_page(struct domain *d, gfn_t gfn, mfn_t mfn,

xen/arch/x86/mm/p2m.c

@@ -850,15 +850,17 @@ p2m_remove_entry(struct p2m_domain *p2m, gfn_t gfn, mfn_t mfn,
 }
 
 int
-guest_physmap_remove_page(struct domain *d, gfn_t gfn,
-                          mfn_t mfn, unsigned int page_order)
+p2m_remove_page(struct domain *d, gfn_t gfn, mfn_t mfn,
+                unsigned int page_order)
 {
     struct p2m_domain *p2m = p2m_get_hostp2m(d);
     int rc;
 
-    /* IOMMU for PV guests is handled in get_page_type() and put_page(). */
     if ( !paging_mode_translate(d) )
-        return 0;
+    {
+        ASSERT_UNREACHABLE();
+        return -EPERM;
+    }
 
     gfn_lock(p2m, gfn, page_order);
     rc = p2m_remove_entry(p2m, gfn, mfn, page_order);
@@ -867,6 +869,17 @@ guest_physmap_remove_page(struct domain *d, gfn_t gfn,
     return rc;
 }
 
+int
+guest_physmap_remove_page(struct domain *d, gfn_t gfn,
+                          mfn_t mfn, unsigned int page_order)
+{
+    /* IOMMU for PV guests is handled in get_page_type() and put_page(). */
+    if ( !paging_mode_translate(d) )
+        return 0;
+
+    return p2m_remove_page(d, gfn, mfn, page_order);
+}
+
 #endif /* CONFIG_HVM */
 
 int
@@ -905,14 +918,14 @@ guest_physmap_add_page(struct domain *d, gfn_t gfn, mfn_t mfn,
         return 0;
     }
 
-    return guest_physmap_add_entry(d, gfn, mfn, page_order, p2m_ram_rw);
+    return p2m_add_page(d, gfn, mfn, page_order, p2m_ram_rw);
 }
 
 #ifdef CONFIG_HVM
 
 int
-guest_physmap_add_entry(struct domain *d, gfn_t gfn, mfn_t mfn,
-                        unsigned int page_order, p2m_type_t t)
+p2m_add_page(struct domain *d, gfn_t gfn, mfn_t mfn,
+             unsigned int page_order, p2m_type_t t)
 {
     struct p2m_domain *p2m = p2m_get_hostp2m(d);
     unsigned long i;
@@ -2724,7 +2737,7 @@ static int p2m_add_foreign(struct domain *tdom, unsigned long fgfn,
     {
         if ( is_special_page(mfn_to_page(prev_mfn)) )
             /* Special pages are simply unhooked from this phys slot */
-            rc = guest_physmap_remove_page(tdom, _gfn(gpfn), prev_mfn, 0);
+            rc = p2m_remove_page(tdom, _gfn(gpfn), prev_mfn, 0);
         else
             /* Normal domain memory is freed, to avoid leaking memory. */
             rc = guest_remove_page(tdom, gpfn);
@@ -2732,7 +2745,7 @@ static int p2m_add_foreign(struct domain *tdom, unsigned long fgfn,
             goto put_both;
     }
     /*
-     * Create the new mapping. Can't use guest_physmap_add_page() because it
+     * Create the new mapping. Can't use p2m_add_page() because it
      * will update the m2p table which will result in  mfn -> gpfn of dom0
      * and not fgfn of domU.
      */
@@ -2846,7 +2859,7 @@ int xenmem_add_to_physmap_one(
     {
         if ( is_special_page(mfn_to_page(prev_mfn)) )
             /* Special pages are simply unhooked from this phys slot. */
-            rc = guest_physmap_remove_page(d, gpfn, prev_mfn, PAGE_ORDER_4K);
+            rc = p2m_remove_page(d, gpfn, prev_mfn, PAGE_ORDER_4K);
         else if ( !mfn_eq(mfn, prev_mfn) )
             /* Normal domain memory is freed, to avoid leaking memory. */
             rc = guest_remove_page(d, gfn_x(gpfn));
@@ -2854,11 +2867,11 @@ int xenmem_add_to_physmap_one(
 
     /* Unmap from old location, if any. */
     if ( !rc && old_gpfn != INVALID_M2P_ENTRY && !gfn_eq(_gfn(old_gpfn), gpfn) )
-        rc = guest_physmap_remove_page(d, _gfn(old_gpfn), mfn, PAGE_ORDER_4K);
+        rc = p2m_remove_page(d, _gfn(old_gpfn), mfn, PAGE_ORDER_4K);
 
     /* Map at new location. */
     if ( !rc )
-        rc = guest_physmap_add_page(d, gpfn, mfn, PAGE_ORDER_4K);
+        rc = p2m_add_page(d, gpfn, mfn, PAGE_ORDER_4K, p2m_ram_rw);
 
  put_all:
     put_gfn(d, gfn_x(gpfn));