From nobody Mon Feb 9 01:20:51 2026 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1557296618; cv=none; d=zoho.com; s=zohoarc; b=eADmVwwUQ+riN2svRHbP5+Y65OGIBeWXNMk9CA9sYV6Cz3LNR53Z9W8A+2/w3JpFHzgEYZO2EnxahNDgVjf2eBixA3yr51e8oSjJjaDVzHwBkzsEuB9h2jNRaIoATO1SEIFH+ZOK480YJZHHNUPeqgnaywy3zpWGxvUBCUI2/FU= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zoho.com; s=zohoarc; t=1557296618; h=Cc:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:Message-ID:References:Sender:Subject:To:ARC-Authentication-Results; bh=l9tf+YRhl35k00uIIVx57FIDKmshjf7+kNkoVpLLqsw=; b=YL6xSsLY/5zm9wYbIWhFOYl33Rm/0VsnyTnoKUI7f6smGFQJBuZefcGnks5ggZUIs1CajSudI2Xz8gRMah9sLhJxE9MwEz+KbMXvPTr7XgrETjlaT1IZ5ZezlvTZoZZGwhyMlAG6Z2GxUeePUsoK5zQjF7bFyKc1fzQcrm8zbsU= ARC-Authentication-Results: i=1; mx.zoho.com; spf=pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail header.from= (p=none dis=none) header.from= Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1557296618823679.7849308648248; Tue, 7 May 2019 23:23:38 -0700 (PDT) Received: from localhost ([127.0.0.1]:60155 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hOFzL-0007zU-EP for importer@patchew.org; Wed, 08 May 2019 02:23:35 -0400 Received: from eggs.gnu.org ([209.51.188.92]:40001) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hOFrv-0000ys-FI for qemu-devel@nongnu.org; Wed, 08 May 2019 02:15:56 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hOFru-0004JM-DB for qemu-devel@nongnu.org; Wed, 08 May 2019 02:15:55 -0400 Received: from mx1.redhat.com ([209.132.183.28]:59764) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hOFru-0004Ib-5Z for qemu-devel@nongnu.org; Wed, 08 May 2019 02:15:54 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 8722F5946B for ; Wed, 8 May 2019 06:15:53 +0000 (UTC) Received: from xz-x1.nay.redhat.com (dhcp-15-205.nay.redhat.com [10.66.15.205]) by smtp.corp.redhat.com (Postfix) with ESMTP id 7382716BF0; Wed, 8 May 2019 06:15:51 +0000 (UTC) From: Peter Xu To: qemu-devel@nongnu.org Date: Wed, 8 May 2019 14:15:20 +0800 Message-Id: <20190508061523.17666-9-peterx@redhat.com> In-Reply-To: <20190508061523.17666-1-peterx@redhat.com> References: <20190508061523.17666-1-peterx@redhat.com> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Wed, 08 May 2019 06:15:53 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH 08/11] kvm: Persistent per kvmslot dirty bitmap X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Laurent Vivier , Paolo Bonzini , "Dr . David Alan Gilbert" , peterx@redhat.com, Juan Quintela Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" 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 --- accel/kvm/kvm-all.c | 39 +++++++++++++++++++++------------------ include/sysemu/kvm_int.h | 2 ++ 2 files changed, 23 insertions(+), 18 deletions(-) diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c index b686531586..334c610918 100644 --- a/accel/kvm/kvm-all.c +++ b/accel/kvm/kvm-all.c @@ -497,31 +497,14 @@ static int kvm_physical_sync_dirty_bitmap(KVMMemoryLi= stener *kml, return 0; } =20 - /* XXX bad kernel interface alert - * For dirty bitmap, kernel allocates array of size aligned to - * bits-per-long. But for case when the kernel is 64bits and - * the userspace is 32bits, userspace can't align to the same - * bits-per-long, since sizeof(long) is different between kernel - * and user space. This way, userspace will provide buffer which - * may be 4 bytes less than the kernel will use, resulting in - * userspace memory corruption (which is not detectable by valgrind - * too, in most cases). - * So for now, let's align to 64 instead of HOST_LONG_BITS here, in - * a hope that sizeof(long) won't become >8 any time soon. - */ - size =3D ALIGN(((mem->memory_size) >> TARGET_PAGE_BITS), - /*HOST_LONG_BITS*/ 64) / 8; - d.dirty_bitmap =3D g_malloc0(size); - + d.dirty_bitmap =3D mem->dirty_bmap; d.slot =3D mem->slot | (kml->as_id << 16); if (kvm_vm_ioctl(s, KVM_GET_DIRTY_LOG, &d) =3D=3D -1) { DPRINTF("ioctl failed %d\n", errno); - g_free(d.dirty_bitmap); return -1; } =20 kvm_get_dirty_pages_log_range(section, d.dirty_bitmap); - g_free(d.dirty_bitmap); } =20 return 0; @@ -765,6 +748,7 @@ static void kvm_set_phys_mem(KVMMemoryListener *kml, MemoryRegion *mr =3D section->mr; bool writeable =3D !mr->readonly && !mr->rom_device; hwaddr start_addr, size; + unsigned long bmap_size; void *ram; =20 if (!memory_region_is_ram(mr)) { @@ -796,6 +780,8 @@ static void kvm_set_phys_mem(KVMMemoryListener *kml, } =20 /* unregister the slot */ + g_free(mem->dirty_bmap); + mem->dirty_bmap =3D NULL; mem->memory_size =3D 0; mem->flags =3D 0; err =3D kvm_set_user_memory_region(kml, mem, false); @@ -807,12 +793,29 @@ static void kvm_set_phys_mem(KVMMemoryListener *kml, return; } =20 + /* + * XXX bad kernel interface alert For dirty bitmap, kernel + * allocates array of size aligned to bits-per-long. But for case + * when the kernel is 64bits and the userspace is 32bits, + * userspace can't align to the same bits-per-long, since + * sizeof(long) is different between kernel and user space. This + * way, userspace will provide buffer which may be 4 bytes less + * than the kernel will use, resulting in userspace memory + * corruption (which is not detectable by valgrind too, in most + * cases). So for now, let's align to 64 instead of + * HOST_LONG_BITS here, in a hope that sizeof(long) won't become + * >8 any time soon. + */ + bmap_size =3D ALIGN((size >> TARGET_PAGE_BITS), + /*HOST_LONG_BITS*/ 64) / 8; + /* register the new slot */ mem =3D kvm_alloc_slot(kml); mem->memory_size =3D size; mem->start_addr =3D start_addr; mem->ram =3D ram; mem->flags =3D kvm_mem_flags(mr); + mem->dirty_bmap =3D g_malloc0(bmap_size); =20 err =3D kvm_set_user_memory_region(kml, mem, true); if (err) { 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; =20 typedef struct KVMMemoryListener { --=20 2.17.1