diff options
| author | Peter Xu <peterx@redhat.com> | 2019-06-03 14:50:53 +0800 |
|---|---|---|
| committer | Juan Quintela <quintela@redhat.com> | 2019-07-15 15:39:03 +0200 |
| commit | 9f4bf4baa8b820c7930e23c9566c9493db7e1d25 (patch) | |
| tree | f5dc29b8ced986ff6c8dd73c471799f200dfdefa | |
| parent | 4a12a11a39a6d8399dd222ae2cebe08a8529224a (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>
| -rw-r--r-- | accel/kvm/kvm-all.c | 10 | ||||
| -rw-r--r-- | include/sysemu/kvm_int.h | 2 |
2 files changed, 9 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); diff --git a/include/sysemu/kvm_int.h b/include/sysemu/kvm_int.h index f838412491..687a2ee423 100644 --- a/include/sysemu/kvm_int.h +++ b/include/sysemu/kvm_int.h @@ -21,6 +21,8 @@ typedef struct KVMSlot int slot; int flags; int old_flags; + /* Dirty bitmap cache for the slot */ + unsigned long *dirty_bmap; } KVMSlot; typedef struct KVMMemoryListener { |