[Qemu-devel] [PATCH 2/5] xen mapcache: Check if a memory space has moved.

[Anthony PERARD <anthony.perard@citrix.com>]

This patch change 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>
---
 xen-all.c      |   19 +++++++++++++++++++
 xen-mapcache.c |    8 ++++++--
 xen-mapcache.h |    1 +
 3 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/xen-all.c b/xen-all.c
index b5e28ab..40e8869 100644
--- a/xen-all.c
+++ b/xen-all.c
@@ -83,6 +83,8 @@ typedef struct XenIOState {
     Notifier exit;
 } XenIOState;
 
+XenIOState *xen_io_state = NULL;
+
 /* Xen specific function for piix pci */
 
 int xen_pci_slot_get_pirq(PCIDevice *pci_dev, int irq_num)
@@ -218,6 +220,22 @@ static XenPhysmap *get_physmapping(XenIOState *state,
     return NULL;
 }
 
+target_phys_addr_t xen_addr_actually_is(target_phys_addr_t start_addr, ram_addr_t size)
+{
+    if (xen_io_state) {
+        target_phys_addr_t addr = start_addr & TARGET_PAGE_MASK;
+        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,
@@ -891,6 +909,7 @@ int xen_hvm_init(void)
     XenIOState *state;
 
     state = g_malloc0(sizeof (XenIOState));
+    xen_io_state = state;
 
     state->xce_handle = xen_xc_evtchn_open(NULL, 0);
     if (state->xce_handle == XC_HANDLER_INITIAL_VALUE) {
diff --git a/xen-mapcache.c b/xen-mapcache.c
index 7bcb86e..73927ab 100644
--- a/xen-mapcache.c
+++ b/xen-mapcache.c
@@ -191,10 +191,14 @@ 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_offset = phys_addr & (MCACHE_BUCKET_SIZE - 1);
+    target_phys_addr_t address_index;
+    target_phys_addr_t address_offset;
     target_phys_addr_t __size = size;
 
+    phys_addr = xen_addr_actually_is(phys_addr, size);
+    address_index  = phys_addr >> MCACHE_BUCKET_SHIFT;
+    address_offset = phys_addr & (MCACHE_BUCKET_SIZE - 1);
+
     trace_xen_map_cache(phys_addr);
 
     if (address_index == mapcache->last_address_index && !lock && !__size) {
diff --git a/xen-mapcache.h b/xen-mapcache.h
index da874ca..5e561c5 100644
--- a/xen-mapcache.h
+++ b/xen-mapcache.h
@@ -19,6 +19,7 @@ uint8_t *xen_map_cache(target_phys_addr_t phys_addr, target_phys_addr_t size,
 ram_addr_t xen_ram_addr_from_mapcache(void *ptr);
 void xen_invalidate_map_cache_entry(uint8_t *buffer);
 void xen_invalidate_map_cache(void);
+target_phys_addr_t xen_addr_actually_is(target_phys_addr_t start_addr, ram_addr_t size);
 
 #else
 
-- 
Anthony PERARD