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[Qemu-devel] [PATCH v4 08/11] kvm: Persistent per kvmslot dirty bitmap
From: |
Peter Xu |
Subject: |
[Qemu-devel] [PATCH v4 08/11] kvm: Persistent per kvmslot dirty bitmap |
Date: |
Mon, 3 Jun 2019 14:50:53 +0800 |
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 <address@hidden>
---
accel/kvm/kvm-all.c | 10 +++++++---
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 b686531586..9fb0694772 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -511,17 +511,19 @@ 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;
@@ -796,6 +798,8 @@ 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 {
--
2.17.1
- [Qemu-devel] [PATCH v4 00/11] kvm/migration: support KVM_CLEAR_DIRTY_LOG, Peter Xu, 2019/06/03
- [Qemu-devel] [PATCH v4 01/11] migration: No need to take rcu during sync_dirty_bitmap, Peter Xu, 2019/06/03
- [Qemu-devel] [PATCH v4 02/11] memory: Remove memory_region_get_dirty(), Peter Xu, 2019/06/03
- [Qemu-devel] [PATCH v4 03/11] memory: Don't set migration bitmap when without migration, Peter Xu, 2019/06/03
- [Qemu-devel] [PATCH v4 04/11] bitmap: Add bitmap_copy_with_{src|dst}_offset(), Peter Xu, 2019/06/03
- [Qemu-devel] [PATCH v4 05/11] memory: Pass mr into snapshot_and_clear_dirty, Peter Xu, 2019/06/03
- [Qemu-devel] [PATCH v4 06/11] memory: Introduce memory listener hook log_clear(), Peter Xu, 2019/06/03
- [Qemu-devel] [PATCH v4 07/11] kvm: Update comments for sync_dirty_bitmap, Peter Xu, 2019/06/03
- [Qemu-devel] [PATCH v4 08/11] kvm: Persistent per kvmslot dirty bitmap,
Peter Xu <=
- [Qemu-devel] [PATCH v4 09/11] kvm: Introduce slots lock for memory listener, Peter Xu, 2019/06/03
- [Qemu-devel] [PATCH v4 10/11] kvm: Support KVM_CLEAR_DIRTY_LOG, Peter Xu, 2019/06/03
- [Qemu-devel] [PATCH v4 11/11] migration: Split log_clear() into smaller chunks, Peter Xu, 2019/06/03