From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:48619) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gRZJ5-00007B-0M for qemu-devel@nongnu.org; Tue, 27 Nov 2018 04:05:27 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gRZIv-00010c-I5 for qemu-devel@nongnu.org; Tue, 27 Nov 2018 04:05:22 -0500 Received: from mx1.redhat.com ([209.132.183.28]:62085) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gRZIv-0000yT-3y for qemu-devel@nongnu.org; Tue, 27 Nov 2018 04:05:13 -0500 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id A6F63307D867 for ; Tue, 27 Nov 2018 09:05:11 +0000 (UTC) References: <1543238443-4993-1-git-send-email-pbonzini@redhat.com> <20181126173604-mutt-send-email-mst@kernel.org> From: Paolo Bonzini Message-ID: <6cd98ced-a043-18c0-3aa5-4cda15c76ec5@redhat.com> Date: Tue, 27 Nov 2018 10:04:59 +0100 MIME-Version: 1.0 In-Reply-To: <20181126173604-mutt-send-email-mst@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 0/5] vhost: enable for all targets List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Michael S. Tsirkin" Cc: qemu-devel@nongnu.org, =?UTF-8?Q?Marc-Andr=c3=a9_Lureau?= On 26/11/18 23:43, Michael S. Tsirkin wrote: > On Mon, Nov 26, 2018 at 02:20:38PM +0100, Paolo Bonzini wrote: >> vhost does not have to be supported only if KVM is present, in fact >> vhost-user does not even need any kind of kernel support. This series >> changes this. The rationale is that, when vhost-user-test.c will be >> converted to qgraph, it will be able to test vhost-user support >> for virtio-mmio backend even on x86. > > The reason for limiting it to KVM was very simple: > it has the same set of problems with ordering > as mttcg. > > So I guess it's fine but I think we must then limit it > to when tcg emits fence instructions. > > Otherwise we'll get subtle race conditions. Got it, I'll take a look. However, right now you _can_ use vhost with tcg as long as e.g. qemu-system-x86_64 is compiled with KVM support, so this patch is not changing anything in this respect; the bug is independent of this series. Paolo