[dpdk-dev] [dpdk-stable] [PATCH v4 1/6] vhost: fix windows vm hang
On Mon, Sep 05, 2016 at 05:25:31AM +, Wang, Zhihong wrote: > > > > -Original Message- > > From: Yuanhan Liu [mailto:yuanhan.liu at linux.intel.com] > > Sent: Monday, September 5, 2016 1:25 PM > > To: Wang, Zhihong > > Cc: dev at dpdk.org; maxime.coquelin at redhat.com; > > yuanhan.liu at linux.intel.com; thomas.monjalon at 6wind.com; > > stable at dpdk.org > > Subject: Re: [dpdk-stable] [PATCH v4 1/6] vhost: fix windows vm hang > > > > On Mon, Aug 29, 2016 at 11:35:59PM -0400, Zhihong Wang wrote: > > > This patch fixes a Windows VM compatibility issue in DPDK 16.07 vhost > > code, > > > which causes the guest to hang once any packets are enqueued when > > mrg_rxbuf > > > is turned on. > > > > This commit log lacks two important pieces: why does the hang happen and > > how does your patch fix it. > > Okay, I'll add it in v5. > > > > > > How to test? > > > > > > 1. Start testpmd in the host with a vhost port. > > > > > > 2. Start a Windows VM image with qemu and connect to the vhost port. > > > > > > 3. Start io forwarding with tx_first in host testpmd. > > > > > > For 16.07 code, the Windows VM will hang once any packets are enqueued. > > > > > > Cc: > > > Signed-off-by: Zhihong Wang > > > --- > > > lib/librte_vhost/vhost_rxtx.c | 17 - > > > 1 file changed, 12 insertions(+), 5 deletions(-) > > > > > > diff --git a/lib/librte_vhost/vhost_rxtx.c b/lib/librte_vhost/vhost_rxtx.c > > > index 08a73fd..5806f99 100644 > > > --- a/lib/librte_vhost/vhost_rxtx.c > > > +++ b/lib/librte_vhost/vhost_rxtx.c > > > @@ -384,6 +384,8 @@ copy_mbuf_to_desc_mergeable(struct virtio_net > > *dev, struct vhost_virtqueue *vq, > > > uint16_t start_idx = vq->last_used_idx; > > > uint16_t cur_idx = start_idx; > > > uint64_t desc_addr; > > > + uint32_t desc_chain_head; > > > + uint32_t desc_chain_len; > > > > What's the point of introducing "desc_chain_len"? It has the same value > > of desc_offset. > > No it's not, desc_offset is the offset of the current desc only. > That's where the old code goes wrong. Oh, right. --yliu
[dpdk-dev] [dpdk-stable] [PATCH v4 1/6] vhost: fix windows vm hang
On Mon, Aug 29, 2016 at 11:35:59PM -0400, Zhihong Wang wrote: > This patch fixes a Windows VM compatibility issue in DPDK 16.07 vhost code, > which causes the guest to hang once any packets are enqueued when mrg_rxbuf > is turned on. This commit log lacks two important pieces: why does the hang happen and how does your patch fix it. > How to test? > > 1. Start testpmd in the host with a vhost port. > > 2. Start a Windows VM image with qemu and connect to the vhost port. > > 3. Start io forwarding with tx_first in host testpmd. > > For 16.07 code, the Windows VM will hang once any packets are enqueued. > > Cc: > Signed-off-by: Zhihong Wang > --- > lib/librte_vhost/vhost_rxtx.c | 17 - > 1 file changed, 12 insertions(+), 5 deletions(-) > > diff --git a/lib/librte_vhost/vhost_rxtx.c b/lib/librte_vhost/vhost_rxtx.c > index 08a73fd..5806f99 100644 > --- a/lib/librte_vhost/vhost_rxtx.c > +++ b/lib/librte_vhost/vhost_rxtx.c > @@ -384,6 +384,8 @@ copy_mbuf_to_desc_mergeable(struct virtio_net *dev, > struct vhost_virtqueue *vq, > uint16_t start_idx = vq->last_used_idx; > uint16_t cur_idx = start_idx; > uint64_t desc_addr; > + uint32_t desc_chain_head; > + uint32_t desc_chain_len; What's the point of introducing "desc_chain_len"? It has the same value of desc_offset. --yliu
[dpdk-dev] [dpdk-stable] [PATCH v4 1/6] vhost: fix windows vm hang
> -Original Message-
> From: Yuanhan Liu [mailto:yuanhan.liu at linux.intel.com]
> Sent: Monday, September 5, 2016 1:25 PM
> To: Wang, Zhihong
> Cc: dev at dpdk.org; maxime.coquelin at redhat.com;
> yuanhan.liu at linux.intel.com; thomas.monjalon at 6wind.com;
> stable at dpdk.org
> Subject: Re: [dpdk-stable] [PATCH v4 1/6] vhost: fix windows vm hang
>
> On Mon, Aug 29, 2016 at 11:35:59PM -0400, Zhihong Wang wrote:
> > This patch fixes a Windows VM compatibility issue in DPDK 16.07 vhost
> code,
> > which causes the guest to hang once any packets are enqueued when
> mrg_rxbuf
> > is turned on.
>
> This commit log lacks two important pieces: why does the hang happen and
> how does your patch fix it.
Okay, I'll add it in v5.
>
> > How to test?
> >
> > 1. Start testpmd in the host with a vhost port.
> >
> > 2. Start a Windows VM image with qemu and connect to the vhost port.
> >
> > 3. Start io forwarding with tx_first in host testpmd.
> >
> > For 16.07 code, the Windows VM will hang once any packets are enqueued.
> >
> > Cc:
> > Signed-off-by: Zhihong Wang
> > ---
> > lib/librte_vhost/vhost_rxtx.c | 17 -
> > 1 file changed, 12 insertions(+), 5 deletions(-)
> >
> > diff --git a/lib/librte_vhost/vhost_rxtx.c b/lib/librte_vhost/vhost_rxtx.c
> > index 08a73fd..5806f99 100644
> > --- a/lib/librte_vhost/vhost_rxtx.c
> > +++ b/lib/librte_vhost/vhost_rxtx.c
> > @@ -384,6 +384,8 @@ copy_mbuf_to_desc_mergeable(struct virtio_net
> *dev, struct vhost_virtqueue *vq,
> > uint16_t start_idx = vq->last_used_idx;
> > uint16_t cur_idx = start_idx;
> > uint64_t desc_addr;
> > + uint32_t desc_chain_head;
> > + uint32_t desc_chain_len;
>
> What's the point of introducing "desc_chain_len"? It has the same value
> of desc_offset.
No it's not, desc_offset is the offset of the current desc only.
That's where the old code goes wrong.
If you take a look at the virtio spec:
/* le32 is used here for ids for padding reasons. */
struct vring_used_elem {
/* Index of start of used descriptor chain. */
le32 id;
/* Total length of the descriptor chain which was written to. */
le32 len;
};
>
> --yliu
