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authorPeter Xu <peterx@redhat.com>2019-06-03 14:50:53 +0800
committerJuan Quintela <quintela@redhat.com>2019-07-15 15:39:03 +0200
commit9f4bf4baa8b820c7930e23c9566c9493db7e1d25 (patch)
treef5dc29b8ced986ff6c8dd73c471799f200dfdefa /accel
parent4a12a11a39a6d8399dd222ae2cebe08a8529224a (diff)
kvm: Persistent per kvmslot dirty bitmap
When synchronizing dirty bitmap from kernel KVM we do it in a per-kvmslot fashion and we allocate the userspace bitmap for each of the ioctl. This patch instead make the bitmap cache be persistent then we don't need to g_malloc0() every time. More importantly, the cached per-kvmslot dirty bitmap will be further used when we want to add support for the KVM_CLEAR_DIRTY_LOG and this cached bitmap will be used to guarantee we won't clear any unknown dirty bits otherwise that can be a severe data loss issue for migration code. Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Juan Quintela <quintela@redhat.com> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Message-Id: <20190603065056.25211-9-peterx@redhat.com> Signed-off-by: Juan Quintela <quintela@redhat.com>
Diffstat (limited to 'accel')
-rw-r--r--accel/kvm/kvm-all.c10
1 files changed, 7 insertions, 3 deletions
diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index a3df19da56..23ace52b9e 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -516,17 +516,19 @@ static int kvm_physical_sync_dirty_bitmap(KVMMemoryListener *kml,
*/
size = ALIGN(((mem->memory_size) >> TARGET_PAGE_BITS),
/*HOST_LONG_BITS*/ 64) / 8;
- d.dirty_bitmap = g_malloc0(size);
+ if (!mem->dirty_bmap) {
+ /* Allocate on the first log_sync, once and for all */
+ mem->dirty_bmap = g_malloc0(size);
+ }
+ d.dirty_bitmap = mem->dirty_bmap;
d.slot = mem->slot | (kml->as_id << 16);
if (kvm_vm_ioctl(s, KVM_GET_DIRTY_LOG, &d) == -1) {
DPRINTF("ioctl failed %d\n", errno);
- g_free(d.dirty_bitmap);
return -1;
}
kvm_get_dirty_pages_log_range(section, d.dirty_bitmap);
- g_free(d.dirty_bitmap);
}
return 0;
@@ -801,6 +803,8 @@ static void kvm_set_phys_mem(KVMMemoryListener *kml,
}
/* unregister the slot */
+ g_free(mem->dirty_bmap);
+ mem->dirty_bmap = NULL;
mem->memory_size = 0;
mem->flags = 0;
err = kvm_set_user_memory_region(kml, mem, false);