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From: Juan Quintela <quintela@redhat.com>
To: qemu-devel@nongnu.org
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>,
	Juan Quintela <quintela@redhat.com>,
	Laurent Vivier <lvivier@redhat.com>,
	kvm@vger.kernel.org, Thomas Huth <thuth@redhat.com>,
	Richard Henderson <rth@twiddle.net>,
	Paolo Bonzini <pbonzini@redhat.com>, Peter Xu <peterx@redhat.com>
Subject: [PULL 15/19] kvm: Persistent per kvmslot dirty bitmap
Date: Thu, 11 Jul 2019 12:44:08 +0200
Message-ID: <20190711104412.31233-16-quintela@redhat.com> (raw)
In-Reply-To: <20190711104412.31233-1-quintela@redhat.com>

From: Peter Xu <peterx@redhat.com>

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>
Message-Id: <20190603065056.25211-9-peterx@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
---
 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 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 {
-- 
2.21.0


  parent reply index

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-11 10:43 [PULL 00/19] Migration patches Juan Quintela
2019-07-11 10:43 ` [PULL 01/19] migration: fix multifd_recv event typo Juan Quintela
2019-07-11 10:43 ` [PULL 02/19] migration-test: rename parameter to parameter_int Juan Quintela
2019-07-11 10:43 ` [PULL 03/19] migration-test: Add migration multifd test Juan Quintela
2019-07-11 10:43 ` [PULL 04/19] migration/multifd: call multifd_send_sync_main when sending RAM_SAVE_FLAG_EOS Juan Quintela
2019-07-11 10:43 ` [PULL 05/19] migration/xbzrle: update cache and current_data in one place Juan Quintela
2019-07-11 10:43 ` [PULL 06/19] cutils: remove one unnecessary pointer operation Juan Quintela
2019-07-11 10:44 ` [PULL 07/19] migration/multifd: sync packet_num after all thread are done Juan Quintela
2019-07-11 10:44 ` [PULL 08/19] migratioin/ram.c: reset complete_round when we gets a queued page Juan Quintela
2019-07-11 10:44 ` [PULL 09/19] migration: No need to take rcu during sync_dirty_bitmap Juan Quintela
2019-07-11 10:44 ` [PULL 10/19] memory: Don't set migration bitmap when without migration Juan Quintela
2019-07-11 10:44 ` [PULL 11/19] bitmap: Add bitmap_copy_with_{src|dst}_offset() Juan Quintela
2019-07-11 10:44 ` [PULL 12/19] memory: Pass mr into snapshot_and_clear_dirty Juan Quintela
2019-07-11 10:44 ` [PULL 13/19] memory: Introduce memory listener hook log_clear() Juan Quintela
2019-07-11 10:44 ` [PULL 14/19] kvm: Update comments for sync_dirty_bitmap Juan Quintela
2019-07-11 10:44 ` Juan Quintela [this message]
2019-07-11 10:44 ` [PULL 16/19] kvm: Introduce slots lock for memory listener Juan Quintela
2019-07-11 10:44 ` [PULL 17/19] kvm: Support KVM_CLEAR_DIRTY_LOG Juan Quintela
2019-07-11 10:44 ` [PULL 19/19] migration: allow private destination ram with x-ignore-shared Juan Quintela
2019-07-11 11:19 ` [PULL 00/19] Migration patches Paolo Bonzini
2019-07-11 11:32   ` Juan Quintela
2019-07-11 11:34   ` Dr. David Alan Gilbert
2019-07-11 11:40     ` [Qemu-devel] " Peter Maydell
2019-07-11 12:39 ` Peter Maydell
2019-07-12 14:06   ` Juan Quintela
2019-07-11 12:55 ` Christian Borntraeger
2019-07-11 13:01   ` [Qemu-devel] " Peter Maydell
2019-07-11 13:00 ` no-reply
2019-07-12 14:33 ` no-reply
2019-07-12 14:31 Juan Quintela
2019-07-12 14:32 ` [PULL 15/19] kvm: Persistent per kvmslot dirty bitmap Juan Quintela

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