From patchwork Thu Aug 11 11:23:41 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Amit Shah X-Patchwork-Id: 658179 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3s95K73kJLz9sR9 for ; Thu, 11 Aug 2016 21:24:59 +1000 (AEST) Received: from localhost ([::1]:47671 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bXo6b-0005rm-HU for incoming@patchwork.ozlabs.org; Thu, 11 Aug 2016 07:24:57 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:58175) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bXo5f-0004pC-P0 for qemu-devel@nongnu.org; Thu, 11 Aug 2016 07:24:01 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bXo5d-0006D3-16 for qemu-devel@nongnu.org; Thu, 11 Aug 2016 07:23:58 -0400 Received: from mx1.redhat.com ([209.132.183.28]:55452) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bXo5c-0006Cv-PF for qemu-devel@nongnu.org; Thu, 11 Aug 2016 07:23:56 -0400 Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 528C383F45; Thu, 11 Aug 2016 11:23:56 +0000 (UTC) Received: from localhost (ovpn-116-52.phx2.redhat.com [10.3.116.52]) by int-mx10.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u7BBNqlS009802; Thu, 11 Aug 2016 07:23:53 -0400 From: Amit Shah To: Peter Maydell Date: Thu, 11 Aug 2016 16:53:41 +0530 Message-Id: In-Reply-To: References: In-Reply-To: References: X-Scanned-By: MIMEDefang 2.68 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Thu, 11 Aug 2016 11:23:56 +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] [PULL 2.7 1/1] virtio-console: set frontend open permanently for console devs 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: Amit Shah , qemu list Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" From: "Daniel P. Berrange" The virtio-console.c file handles both serial consoles and interactive consoles, since they're backed by the same device model. Since serial devices are expected to be reliable and need to notify the guest when the backend is opened or closed, the virtio-console.c file wires up support for chardev events. This affects both serial consoles and interactive consoles, using a network connection based chardev backend such as 'socket', but not when using a PTY based backend or plain 'file' backends. When the host side is not connected the handle_output() method in virtio-serial-bus.c will drop any data sent by the guest, before it even reaches the virtio-console.c code. This means that if the chardev has a logfile configured, the data will never get logged. Consider for example, configuring a x86_64 guest with a plain UART serial port -chardev socket,id=charserial1,host=127.0.0.1,port=9001,server,nowait,logfile=console1.log,logappend=on -device isa-serial,chardev=charserial1,id=serial1 vs a s390 guest which has to use the virtio-console port -chardev socket,id=charconsole1,host=127.0.0.1,port=9000,server,nowait,logfile=console2.log,logappend=on -device virtconsole,chardev=charconsole1,id=console1 The isa-serial one gets data written to the log regardless of whether a client is connected, while the virtioconsole one only gets data written to the log when a client is connected. There is no need for virtio-serial-bus.c to aggressively drop the data for console devices, as the chardev code is prefectly capable of discarding the data itself. So this patch changes virtconsole devices so that they are always marked as having the host side open. This ensures that the guest OS will always send any data it has (Linux virtio-console hvc driver actually ignores the host open state and sends data regardless, but we should not rely on that), and also prevents the virtio-serial-bus code prematurely discarding data. The behaviour of virtserialport devices is *not* changed, only virtconsole, because for the former, it is important that the guest OSknow exactly when the host side is opened / closed so it can do any protocol re-negotiation that may be required. Fixes bug: https://bugs.launchpad.net/qemu/+bug/1599214 Acked-by: Cornelia Huck Signed-off-by: Daniel P. Berrange Message-Id: <1470241360-3574-2-git-send-email-berrange@redhat.com> Signed-off-by: Amit Shah --- hw/char/virtio-console.c | 25 +++++++++++++++++++++---- 1 file changed, 21 insertions(+), 4 deletions(-) diff --git a/hw/char/virtio-console.c b/hw/char/virtio-console.c index 2e36481..4f0e03d 100644 --- a/hw/char/virtio-console.c +++ b/hw/char/virtio-console.c @@ -85,8 +85,9 @@ static void set_guest_connected(VirtIOSerialPort *port, int guest_connected) { VirtConsole *vcon = VIRTIO_CONSOLE(port); DeviceState *dev = DEVICE(port); + VirtIOSerialPortClass *k = VIRTIO_SERIAL_PORT_GET_CLASS(port); - if (vcon->chr) { + if (vcon->chr && !k->is_console) { qemu_chr_fe_set_open(vcon->chr, guest_connected); } @@ -156,9 +157,25 @@ static void virtconsole_realize(DeviceState *dev, Error **errp) } if (vcon->chr) { - vcon->chr->explicit_fe_open = 1; - qemu_chr_add_handlers(vcon->chr, chr_can_read, chr_read, chr_event, - vcon); + /* + * For consoles we don't block guest data transfer just + * because nothing is connected - we'll just let it go + * whetherever the chardev wants - /dev/null probably. + * + * For serial ports we need 100% reliable data transfer + * so we use the opened/closed signals from chardev to + * trigger open/close of the device + */ + if (k->is_console) { + vcon->chr->explicit_fe_open = 0; + qemu_chr_add_handlers(vcon->chr, chr_can_read, chr_read, + NULL, vcon); + virtio_serial_open(port); + } else { + vcon->chr->explicit_fe_open = 1; + qemu_chr_add_handlers(vcon->chr, chr_can_read, chr_read, + chr_event, vcon); + } } }