Dummys are simple anonymous mappings that are placed instead
of regular foreign mappings in certain situations when we need
to postpone the actual mapping but still have to give a
memory region to QEMU to play with.
This is planned to be used for restore on Xen.
Signed-off-by: Igor Druzhinin <igor.druzhi...@citrix.com>
---
hw/i386/xen/xen-mapcache.c | 40 ++++++++++++++++++++++++++++++++--------
1 file changed, 32 insertions(+), 8 deletions(-)
diff --git a/hw/i386/xen/xen-mapcache.c b/hw/i386/xen/xen-mapcache.c
index e60156c..cd4e746 100644
--- a/hw/i386/xen/xen-mapcache.c
+++ b/hw/i386/xen/xen-mapcache.c
@@ -53,6 +53,8 @@ typedef struct MapCacheEntry {
uint8_t *vaddr_base;
unsigned long *valid_mapping;
uint8_t lock;
+#define XEN_MAPCACHE_ENTRY_DUMMY (1 << 0)
+ uint8_t flags;
hwaddr size;
struct MapCacheEntry *next;
} MapCacheEntry;
@@ -150,7 +152,8 @@ void xen_map_cache_init(phys_offset_to_gaddr_t f, void
*opaque)
static void xen_remap_bucket(MapCacheEntry *entry,
hwaddr size,
- hwaddr address_index)
+ hwaddr address_index,
+ bool dummy)
{
uint8_t *vaddr_base;
xen_pfn_t *pfns;
@@ -177,11 +180,27 @@ static void xen_remap_bucket(MapCacheEntry *entry,
pfns[i] = (address_index << (MCACHE_BUCKET_SHIFT-XC_PAGE_SHIFT)) + i;
}
- vaddr_base = xenforeignmemory_map(xen_fmem, xen_domid,
PROT_READ|PROT_WRITE,
- nb_pfn, pfns, err);
- if (vaddr_base == NULL) {
- perror("xenforeignmemory_map");
- exit(-1);
+ if (!dummy) {
+ vaddr_base = xenforeignmemory_map(xen_fmem, xen_domid,
+ PROT_READ|PROT_WRITE,
+ nb_pfn, pfns, err);
+ if (vaddr_base == NULL) {
+ perror("xenforeignmemory_map");
+ exit(-1);
+ }
+ entry->flags &= ~(XEN_MAPCACHE_ENTRY_DUMMY);
+ } else {
+ /*
+ * We create dummy mappings where we are unable to create a foreign
+ * mapping immediately due to certain circumstances (i.e. on resume
now)
+ */
+ vaddr_base = mmap(NULL, size, PROT_READ|PROT_WRITE,
+ MAP_ANON|MAP_SHARED, -1, 0);
+ if (vaddr_base == NULL) {
+ perror("mmap");
+ exit(-1);
+ }
+ entry->flags |= XEN_MAPCACHE_ENTRY_DUMMY;
}
entry->vaddr_base = vaddr_base;
@@ -211,6 +230,7 @@ static uint8_t *xen_map_cache_unlocked(hwaddr phys_addr,
hwaddr size,
hwaddr cache_size = size;
hwaddr test_bit_size;
bool translated = false;
+ bool dummy = false;
tryagain:
address_index = phys_addr >> MCACHE_BUCKET_SHIFT;
@@ -262,14 +282,14 @@ tryagain:
if (!entry) {
entry = g_malloc0(sizeof (MapCacheEntry));
pentry->next = entry;
- xen_remap_bucket(entry, cache_size, address_index);
+ xen_remap_bucket(entry, cache_size, address_index, dummy);
} else if (!entry->lock) {
if (!entry->vaddr_base || entry->paddr_index != address_index ||
entry->size != cache_size ||
!test_bits(address_offset >> XC_PAGE_SHIFT,
test_bit_size >> XC_PAGE_SHIFT,
entry->valid_mapping)) {
- xen_remap_bucket(entry, cache_size, address_index);
+ xen_remap_bucket(entry, cache_size, address_index, dummy);
}
}
@@ -282,6 +302,10 @@ tryagain:
translated = true;
goto tryagain;
}
+ if (!dummy && runstate_check(RUN_STATE_INMIGRATE)) {
+ dummy = true;
+ goto tryagain;
+ }
trace_xen_map_cache_return(NULL);
return NULL;
}
--
2.7.4
