From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45667) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZKhI2-0006nR-94 for qemu-devel@nongnu.org; Thu, 30 Jul 2015 02:26:03 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZKhHz-0002iw-1k for qemu-devel@nongnu.org; Thu, 30 Jul 2015 02:26:02 -0400 Received: from mx1.redhat.com ([209.132.183.28]:45430) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZKhHy-0002ig-RV for qemu-devel@nongnu.org; Thu, 30 Jul 2015 02:25:58 -0400 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) by mx1.redhat.com (Postfix) with ESMTPS id 174B991D3E for ; Thu, 30 Jul 2015 06:25:58 +0000 (UTC) Date: Thu, 30 Jul 2015 09:25:55 +0300 From: "Michael S. Tsirkin" Message-ID: <20150730092342-mutt-send-email-mst@redhat.com> References: <1438170589-139333-1-git-send-email-imammedo@redhat.com> <20150729180313-mutt-send-email-mst@redhat.com> <20150730082218.79283ab4@nial.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150730082218.79283ab4@nial.brq.redhat.com> Subject: Re: [Qemu-devel] [PATCH for-2.4 v2 0/2] vhost: check if vhost has capacity for hotplugged memory List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Igor Mammedov Cc: pbonzini@redhat.com, qemu-devel@nongnu.org On Thu, Jul 30, 2015 at 08:22:18AM +0200, Igor Mammedov wrote: > On Wed, 29 Jul 2015 18:03:36 +0300 > "Michael S. Tsirkin" wrote: > > > On Wed, Jul 29, 2015 at 01:49:47PM +0200, Igor Mammedov wrote: > > > v1->v2: > > > * replace probbing with checking for > > > /sys/module/vhost/parameters/max_mem_regions and > > > if it's missing has non wrong value return > > > hardcoded legacy limit (64 slots). > > > > > > it's defensive patchset which helps to avoid QEMU crashing > > > at memory hotplug time by checking that vhost has free capacity > > > for an additional memory slot. > > > > What if vhost is added after memory hotplug? Don't you need > > to check that as well? > vhost device can be hotplugged after memory hotplug as far as > current slots count doesn't exceed its limit, > if limit is exceeded device_add would fail or virtio device > would fallback to non vhost mode at its start-up (depends on > how particular device treats vhost_start failure). Where exactly does it fail? memory_listener_register returns void so clearly it's not that ... > > > > > > > > > > Igor Mammedov (2): > > > vhost: add vhost_has_free_slot() interface > > > pc-dimm: add vhost slots limit check before commiting to hotplug > > > > > > hw/mem/pc-dimm.c | 7 +++++++ > > > hw/virtio/vhost-backend.c | 21 ++++++++++++++++++++- > > > hw/virtio/vhost-user.c | 8 +++++++- > > > hw/virtio/vhost.c | 21 +++++++++++++++++++++ > > > include/hw/virtio/vhost-backend.h | 2 ++ > > > include/hw/virtio/vhost.h | 1 + > > > stubs/Makefile.objs | 1 + > > > stubs/vhost.c | 6 ++++++ > > > 8 files changed, 65 insertions(+), 2 deletions(-) > > > create mode 100644 stubs/vhost.c > > > > > > -- > > > 1.8.3.1