xen mapcache: check if memory region has moved.

This patch changes the xen_map_cache behavior. Before trying to map a guest
addr, mapcache will look into the list of range of address that have been moved
(physmap/set_memory). There is currently one memory space like this, the vram,
"moved" from were it's allocated to were the guest will look into.

This help to have a succefull migration.

Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>

xen-all.c

@@ -225,6 +225,22 @@ static XenPhysmap *get_physmapping(XenIOState *state,
     return NULL;
 }
 
+static target_phys_addr_t xen_phys_offset_to_gaddr(target_phys_addr_t start_addr,
+                                                   ram_addr_t size, void *opaque)
+{
+    target_phys_addr_t addr = start_addr & TARGET_PAGE_MASK;
+    XenIOState *xen_io_state = opaque;
+    XenPhysmap *physmap = NULL;
+
+    QLIST_FOREACH(physmap, &xen_io_state->physmap, list) {
+        if (range_covers_byte(physmap->phys_offset, physmap->size, addr)) {
+            return physmap->start_addr;
+        }
+    }
+
+    return start_addr;
+}
+
 #if CONFIG_XEN_CTRL_INTERFACE_VERSION >= 340
 static int xen_add_to_physmap(XenIOState *state,
                               target_phys_addr_t start_addr,
@@ -1043,7 +1059,7 @@ int xen_hvm_init(void)
     }
 
     /* Init RAM management */
-    xen_map_cache_init();
+    xen_map_cache_init(xen_phys_offset_to_gaddr, state);
     xen_ram_init(ram_size);
 
     qemu_add_vm_change_state_handler(xen_hvm_change_state_handler, state);

xen-mapcache.c

@@ -78,6 +78,9 @@ typedef struct MapCache {
     uint8_t *last_address_vaddr;
     unsigned long max_mcache_size;
     unsigned int mcache_bucket_shift;
+
+    phys_offset_to_gaddr_t phys_offset_to_gaddr;
+    void *opaque;
 } MapCache;
 
 static MapCache *mapcache;
@@ -91,13 +94,16 @@ static inline int test_bits(int nr, int size, const unsigned long *addr)
         return 0;
 }
 
-void xen_map_cache_init(void)
+void xen_map_cache_init(phys_offset_to_gaddr_t f, void *opaque)
 {
     unsigned long size;
     struct rlimit rlimit_as;
 
     mapcache = g_malloc0(sizeof (MapCache));
 
+    mapcache->phys_offset_to_gaddr = f;
+    mapcache->opaque = opaque;
+
     QTAILQ_INIT(&mapcache->locked_entries);
     mapcache->last_address_index = -1;
 
@@ -193,9 +199,14 @@ uint8_t *xen_map_cache(target_phys_addr_t phys_addr, target_phys_addr_t size,
                        uint8_t lock)
 {
     MapCacheEntry *entry, *pentry = NULL;
-    target_phys_addr_t address_index  = phys_addr >> MCACHE_BUCKET_SHIFT;
+    target_phys_addr_t address_index;
-    target_phys_addr_t address_offset = phys_addr & (MCACHE_BUCKET_SIZE - 1);
+    target_phys_addr_t address_offset;
     target_phys_addr_t __size = size;
+    bool translated = false;
+
+tryagain:
+    address_index  = phys_addr >> MCACHE_BUCKET_SHIFT;
+    address_offset = phys_addr & (MCACHE_BUCKET_SIZE - 1);
 
     trace_xen_map_cache(phys_addr);
 
@@ -237,6 +248,11 @@ uint8_t *xen_map_cache(target_phys_addr_t phys_addr, target_phys_addr_t size,
     if(!test_bits(address_offset >> XC_PAGE_SHIFT, size >> XC_PAGE_SHIFT,
                 entry->valid_mapping)) {
         mapcache->last_address_index = -1;
+        if (!translated && mapcache->phys_offset_to_gaddr) {
+            phys_addr = mapcache->phys_offset_to_gaddr(phys_addr, size, mapcache->opaque);
+            translated = true;
+            goto tryagain;
+        }
         trace_xen_map_cache_return(NULL);
         return NULL;
     }

xen-mapcache.h

@@ -11,9 +11,13 @@
 
 #include <stdlib.h>
 
+typedef target_phys_addr_t (*phys_offset_to_gaddr_t)(target_phys_addr_t start_addr,
+                                                     ram_addr_t size,
+                                                     void *opaque);
 #ifdef CONFIG_XEN
 
-void xen_map_cache_init(void);
+void xen_map_cache_init(phys_offset_to_gaddr_t f,
+                        void *opaque);
 uint8_t *xen_map_cache(target_phys_addr_t phys_addr, target_phys_addr_t size,
                        uint8_t lock);
 ram_addr_t xen_ram_addr_from_mapcache(void *ptr);
@@ -22,7 +26,8 @@ void xen_invalidate_map_cache(void);
 
 #else
 
-static inline void xen_map_cache_init(void)
+static inline void xen_map_cache_init(phys_offset_to_gaddr_t f,
+                                      void *opaque)
 {
 }