From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Wang Subject: Re: [RFC V4 PATCH 7/8] vhost: packed ring support Date: Wed, 23 May 2018 16:57:46 +0800 Message-ID: References: <1526473941-16199-1-git-send-email-jasowang@redhat.com> <1526473941-16199-8-git-send-email-jasowang@redhat.com> <20180522165448.GA13523@wei-ubt> <20180523071727.GA13373@wei-ubt> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Cc: mst@redhat.com, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, jfreimann@redhat.com, tiwei.bie@intel.com To: Wei Xu Return-path: In-Reply-To: <20180523071727.GA13373@wei-ubt> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 2018年05月23日 15:17, Wei Xu wrote: > On Wed, May 23, 2018 at 09:39:28AM +0800, Jason Wang wrote: >> >> On 2018年05月23日 00:54, Wei Xu wrote: >>> On Wed, May 16, 2018 at 08:32:20PM +0800, Jason Wang wrote: >>>> Signed-off-by: Jason Wang >>>> --- >>>> drivers/vhost/net.c | 3 +- >>>> drivers/vhost/vhost.c | 539 ++++++++++++++++++++++++++++++++++++++++++++++---- >>>> drivers/vhost/vhost.h | 8 +- >>>> 3 files changed, 513 insertions(+), 37 deletions(-) >>>> >>>> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c >>>> index 8304c30..f2a0f5b 100644 >>>> --- a/drivers/vhost/vhost.c >>>> +++ b/drivers/vhost/vhost.c >>>> @@ -1358,6 +1382,8 @@ long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *arg >>>> break; >>>> } >>>> vq->last_avail_idx = s.num; >>>> + if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED)) >>>> + vq->avail_wrap_counter = s.num >> 31; >>>> /* Forget the cached index value. */ >>>> vq->avail_idx = vq->last_avail_idx; >>>> break; >>>> @@ -1366,6 +1392,8 @@ long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *arg >>>> s.num = vq->last_avail_idx; >>>> if (copy_to_user(argp, &s, sizeof s)) >>>> r = -EFAULT; >>>> + if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED)) >>>> + s.num |= vq->avail_wrap_counter << 31; >>>> break; >>>> case VHOST_SET_VRING_ADDR: >>>> if (copy_from_user(&a, argp, sizeof a)) { >>> 'last_used_idx' also needs to be saved/restored here. >>> >>> I have figured out the root cause of broken device after reloading >>> 'virtio-net' module, all indices have been reset for a reloading but >>> 'last_used_idx' is not properly reset in this case. This confuses >>> handle_rx()/tx(). >>> >>> Wei >>> >> Good catch, so we probably need a new ioctl to sync between qemu and vhost. >> >> Something like VHOST_SET/GET_USED_BASE. > Sure, or can we expand 'vhost_vring_state' to keep them done in a bunch? It's port of uapi, so we can't. Thanks > >> Thanks >>