From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39589) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dFldN-0005hi-H4 for qemu-devel@nongnu.org; Tue, 30 May 2017 14:12:46 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dFldJ-0002kk-Hz for qemu-devel@nongnu.org; Tue, 30 May 2017 14:12:45 -0400 Received: from mx1.redhat.com ([209.132.183.28]:32905) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dFldJ-0002jE-Bu for qemu-devel@nongnu.org; Tue, 30 May 2017 14:12:41 -0400 Date: Tue, 30 May 2017 21:12:35 +0300 From: "Michael S. Tsirkin" Message-ID: <20170530210905-mutt-send-email-mst@kernel.org> References: <20170526142858.19931-1-maxime.coquelin@redhat.com> <20170526142858.19931-4-maxime.coquelin@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170526142858.19931-4-maxime.coquelin@redhat.com> Subject: Re: [Qemu-devel] [PATCH v2 3/6] vhost: extend ring information update for IOTLB to all rings List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Maxime Coquelin Cc: peterx@redhat.com, marcandre.lureau@gmail.com, vkaplans@redhat.com, jasowang@redhat.com, wexu@redhat.com, yuanhan.liu@linux.intel.com, qemu-devel@nongnu.org, jfreiman@redhat.com On Fri, May 26, 2017 at 04:28:55PM +0200, Maxime Coquelin wrote: > Vhost-kernel backend need needs > to receive IOTLB entry for used ring > information early, which is done by triggering a miss event on > its address. > > This patch extends this behaviour to all rings information, to be > compatible with vhost-user backend design. Why does vhost-user need it though? > > Signed-off-by: Maxime Coquelin > --- > v2: > - Revert back to existing behaviour, i.e. only send IOTLB updates > at ring enablement time, not at ring address setting time (mst). > - Extend IOTLB misses to all ring addresses, not only used ring. > > hw/virtio/vhost.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c > index 6eddb09..7867034 100644 > --- a/hw/virtio/vhost.c > +++ b/hw/virtio/vhost.c > @@ -1552,11 +1552,15 @@ int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev) > if (vhost_dev_has_iommu(hdev)) { > hdev->vhost_ops->vhost_set_iotlb_callback(hdev, true); > > - /* Update used ring information for IOTLB to work correctly, > - * vhost-kernel code requires for this.*/ > + /* > + * Update rings information for IOTLB to work correctly, > + * vhost-kernel and vhost-user codes require for this. Better just say "Update ring info for vhost iotlb." The rest isn't really informative. > + */ > for (i = 0; i < hdev->nvqs; ++i) { > struct vhost_virtqueue *vq = hdev->vqs + i; > vhost_device_iotlb_miss(hdev, vq->used_phys, true); > + vhost_device_iotlb_miss(hdev, vq->desc_phys, true); > + vhost_device_iotlb_miss(hdev, vq->avail_phys, true); So I don't remember why does vhost in kernel want miss on used at start time. Jason, could you comment on this please? > } > } > return 0; > -- > 2.9.4