From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:58127) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bizlS-0007hC-IH for qemu-devel@nongnu.org; Sun, 11 Sep 2016 04:05:23 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bizlO-0006Xc-BL for qemu-devel@nongnu.org; Sun, 11 Sep 2016 04:05:21 -0400 References: <1473426607-10516-1-git-send-email-maxime.coquelin@redhat.com> <1473426607-10516-2-git-send-email-maxime.coquelin@redhat.com> <9c7c648b-17f7-0273-2066-fd39f4ddf67b@redhat.com> <20160909204714-mutt-send-email-mst@kernel.org> From: Marcel Apfelbaum Message-ID: <0cc674cf-373d-bffd-82d2-634b3b1875f5@redhat.com> Date: Sun, 11 Sep 2016 11:04:36 +0300 MIME-Version: 1.0 In-Reply-To: <20160909204714-mutt-send-email-mst@kernel.org> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v2 1/2] virtio: Add function to check whether backend supports VIRTIO_1 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Michael S. Tsirkin" Cc: Maxime Coquelin , qemu-devel@nongnu.org, cornelia.huck@de.ibm.com, vkaplans@redhat.com, qemu-stable@nongnu.org On 09/09/2016 08:47 PM, Michael S. Tsirkin wrote: > On Fri, Sep 09, 2016 at 08:00:31PM +0300, Marcel Apfelbaum wrote: >> On 09/09/2016 04:10 PM, Maxime Coquelin wrote: >>> This patch adds virtio_test_backend_virtio_1() function to >>> check whether backend supports VIRTIO_F_VERSION_1 before the >>> negociation takes place. >>> >>> Cc: Cornelia Huck >>> Cc: Marcel Apfelbaum >>> Cc: Michael S. Tsirkin >>> Cc: qemu-stable@nongnu.org >>> Signed-off-by: Maxime Coquelin >>> --- >>> hw/virtio/virtio.c | 13 +++++++++++++ >>> include/hw/virtio/virtio.h | 1 + >>> 2 files changed, 14 insertions(+) >>> >>> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c >>> index 74c085c..8b30b69 100644 >>> --- a/hw/virtio/virtio.c >>> +++ b/hw/virtio/virtio.c >>> @@ -1481,6 +1481,19 @@ void virtio_vmstate_save(QEMUFile *f, void *opaque, size_t size) >>> virtio_save(VIRTIO_DEVICE(opaque), f); >>> } >>> >>> +bool virtio_test_backend_virtio_1(VirtIODevice *vdev, Error **errp) >>> +{ >>> + VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev); >>> + uint64_t feature; >>> + >> >> I would set "feature = 0" even if doesn't really matter. >> Anyway: >> >> Reviewed-by: Marcel Apfelbaum >> >> Thanks, >> Marcel > > why wouldn't it matter? Looks like an uninitialized variable to me. because it adds a flag, then it checks only if this specific flag is negotiated, but uninitialized variables are never a good idea. Thanks, Marcel > >>> + virtio_add_feature(&feature, VIRTIO_F_VERSION_1); >>> + >>> + assert(k->get_features != NULL); >>> + feature = k->get_features(vdev, feature, errp); >>> + >>> + return virtio_has_feature(feature, VIRTIO_F_VERSION_1); >>> +} >>> + >>> static int virtio_set_features_nocheck(VirtIODevice *vdev, uint64_t val) >>> { >>> VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev); >>> diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h >>> index d2490c1..3a31754 100644 >>> --- a/include/hw/virtio/virtio.h >>> +++ b/include/hw/virtio/virtio.h >>> @@ -235,6 +235,7 @@ int virtio_set_status(VirtIODevice *vdev, uint8_t val); >>> void virtio_reset(void *opaque); >>> void virtio_update_irq(VirtIODevice *vdev); >>> int virtio_set_features(VirtIODevice *vdev, uint64_t val); >>> +bool virtio_test_backend_virtio_1(VirtIODevice *vdev, Error **errp); >>> >>> /* Base devices. */ >>> typedef struct VirtIOBlkConf VirtIOBlkConf; >>>