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xen/mapcache: add an ability to create dummy mappings

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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.druzhinin@citrix.com>
Reviewed-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
This commit is contained in:
Igor Druzhinin 2017-07-10 23:40:01 +01:00 committed by Stefano Stabellini
parent 697b66d006
commit 759235653d
1 changed files with 36 additions and 8 deletions
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44
hw/i386/xen/xen-mapcache.c
View File

@ -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 +180,25 @@ 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);
}
} 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->vaddr_base = vaddr_base;
@ -190,6 +207,12 @@ static void xen_remap_bucket(MapCacheEntry *entry,
entry->valid_mapping = (unsigned long *) g_malloc0(sizeof(unsigned long) *
BITS_TO_LONGS(size >> XC_PAGE_SHIFT));
if (dummy) {
entry->flags |= XEN_MAPCACHE_ENTRY_DUMMY;
} else {
entry->flags &= ~(XEN_MAPCACHE_ENTRY_DUMMY);
}
ram_block_notify_add(entry->vaddr_base, entry->size);
bitmap_zero(entry->valid_mapping, nb_pfn);
for (i = 0; i < nb_pfn; i++) {
@ -211,6 +234,7 @@ 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 +286,14 @@ 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 +306,10 @@ tryagain:
translated = true;
goto tryagain;
}
if (!dummy && runstate_check(RUN_STATE_INMIGRATE)) {
dummy = true;
goto tryagain;
}
trace_xen_map_cache_return(NULL);
return NULL;
}