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Date:   Fri, 14 Feb 2020 08:47:23 +0100
From:   Christian Borntraeger <borntraeger@...ibm.com>
To:     Eugenio Perez Martin <eperezma@...hat.com>
Cc:     "Michael S. Tsirkin" <mst@...hat.com>,
        "virtualization@...ts.linux-foundation.org" 
        <virtualization@...ts.linux-foundation.org>,
        Stephen Rothwell <sfr@...b.auug.org.au>,
        Linux Next Mailing List <linux-next@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        kvm list <kvm@...r.kernel.org>,
        Halil Pasic <pasic@...ux.ibm.com>,
        Cornelia Huck <cohuck@...hat.com>
Subject: Re: vhost changes (batched) in linux-next after 12/13 trigger random
 crashes in KVM guests after reboot

repro


On 14.02.20 08:43, Christian Borntraeger wrote:
> 
> 
> On 14.02.20 08:40, Eugenio Perez Martin wrote:
>> Hi.
>>
>> Were the vhost and vhost_net modules loaded with dyndbg='+plt'? I miss
>> all the others regular debug traces on that one.
> 
> I did 
> 
>  echo -n 'file drivers/vhost/vhost.c +plt' > control
> and
> echo -n 'file drivers/vhost/net.c +plt'  > control
> 
> but apparently it did not work...me hates dynamic debug.
> 
>>
>> Thanks!
>>
>> On Fri, Feb 14, 2020 at 8:34 AM Christian Borntraeger
>> <borntraeger@...ibm.com> wrote:
>>>
>>> I did
>>> ping -c 20 -f ... ; reboot
>>> twice
>>>
>>> The ping after the first reboot showed .......E
>>>
>>> this was on the host console
>>>
>>> [   55.951885] CPU: 34 PID: 1908 Comm: CPU 0/KVM Not tainted 5.5.0+ #21
>>> [   55.951891] Hardware name: IBM 3906 M04 704 (LPAR)
>>> [   55.951892] Call Trace:
>>> [   55.951902]  [<0000001ede114132>] show_stack+0x8a/0xd0
>>> [   55.951906]  [<0000001edeb0672a>] dump_stack+0x8a/0xb8
>>> [   55.951915]  [<000003ff803736a6>] vhost_vring_ioctl+0x6fe/0x858 [vhost]
>>> [   55.951919]  [<000003ff8042a608>] vhost_net_ioctl+0x510/0x570 [vhost_net]
>>> [   55.951924]  [<0000001ede3c4dd8>] do_vfs_ioctl+0x430/0x6f8
>>> [   55.951926]  [<0000001ede3c5124>] ksys_ioctl+0x84/0xb0
>>> [   55.951927]  [<0000001ede3c51ba>] __s390x_sys_ioctl+0x2a/0x38
>>> [   55.951931]  [<0000001edeb27f72>] system_call+0x2a6/0x2c8
>>> [   55.951949] CPU: 34 PID: 1908 Comm: CPU 0/KVM Not tainted 5.5.0+ #21
>>> [   55.951950] Hardware name: IBM 3906 M04 704 (LPAR)
>>> [   55.951951] Call Trace:
>>> [   55.951952]  [<0000001ede114132>] show_stack+0x8a/0xd0
>>> [   55.951954]  [<0000001edeb0672a>] dump_stack+0x8a/0xb8
>>> [   55.951956]  [<000003ff803736a6>] vhost_vring_ioctl+0x6fe/0x858 [vhost]
>>> [   55.951958]  [<000003ff8042a608>] vhost_net_ioctl+0x510/0x570 [vhost_net]
>>> [   55.951959]  [<0000001ede3c4dd8>] do_vfs_ioctl+0x430/0x6f8
>>> [   55.951961]  [<0000001ede3c5124>] ksys_ioctl+0x84/0xb0
>>> [   55.951962]  [<0000001ede3c51ba>] __s390x_sys_ioctl+0x2a/0x38
>>> [   55.951964]  [<0000001edeb27f72>] system_call+0x2a6/0x2c8
>>> [   55.951997] Guest moved vq 0000000063d896c6 used index from 44 to 0
>>> [   56.609831] unexpected descriptor format for RX: out 0, in 0
>>> [   86.540460] CPU: 6 PID: 1908 Comm: CPU 0/KVM Not tainted 5.5.0+ #21
>>> [   86.540464] Hardware name: IBM 3906 M04 704 (LPAR)
>>> [   86.540466] Call Trace:
>>> [   86.540473]  [<0000001ede114132>] show_stack+0x8a/0xd0
>>> [   86.540477]  [<0000001edeb0672a>] dump_stack+0x8a/0xb8
>>> [   86.540486]  [<000003ff803736a6>] vhost_vring_ioctl+0x6fe/0x858 [vhost]
>>> [   86.540490]  [<000003ff8042a608>] vhost_net_ioctl+0x510/0x570 [vhost_net]
>>> [   86.540494]  [<0000001ede3c4dd8>] do_vfs_ioctl+0x430/0x6f8
>>> [   86.540496]  [<0000001ede3c5124>] ksys_ioctl+0x84/0xb0
>>> [   86.540498]  [<0000001ede3c51ba>] __s390x_sys_ioctl+0x2a/0x38
>>> [   86.540501]  [<0000001edeb27f72>] system_call+0x2a6/0x2c8
>>> [   86.540524] CPU: 6 PID: 1908 Comm: CPU 0/KVM Not tainted 5.5.0+ #21
>>> [   86.540525] Hardware name: IBM 3906 M04 704 (LPAR)
>>> [   86.540526] Call Trace:
>>> [   86.540527]  [<0000001ede114132>] show_stack+0x8a/0xd0
>>> [   86.540528]  [<0000001edeb0672a>] dump_stack+0x8a/0xb8
>>> [   86.540531]  [<000003ff803736a6>] vhost_vring_ioctl+0x6fe/0x858 [vhost]
>>> [   86.540532]  [<000003ff8042a608>] vhost_net_ioctl+0x510/0x570 [vhost_net]
>>> [   86.540534]  [<0000001ede3c4dd8>] do_vfs_ioctl+0x430/0x6f8
>>> [   86.540536]  [<0000001ede3c5124>] ksys_ioctl+0x84/0xb0
>>> [   86.540537]  [<0000001ede3c51ba>] __s390x_sys_ioctl+0x2a/0x38
>>> [   86.540538]  [<0000001edeb27f72>] system_call+0x2a6/0x2c8
>>> [   86.540570] unexpected descriptor format for RX: out 0, in 0
>>> [   86.540577] Unexpected header len for TX: 0 expected 0
>>>
>>>
>>> On 14.02.20 08:06, Eugenio PĂ©rez wrote:
>>>> Hi Christian.
>>>>
>>>> Sorry, that was meant to be applied over previous debug patch.
>>>>
>>>> Here I inline the one meant to be applied over eccb852f1fe6bede630e2e4f1a121a81e34354ab.
>>>>
>>>> Thanks!
>>>>
>>>> From d978ace99e4844b49b794d768385db3d128a4cc0 Mon Sep 17 00:00:00 2001
>>>> From: =?UTF-8?q?Eugenio=20P=C3=A9rez?= <eperezma@...hat.com>
>>>> Date: Fri, 14 Feb 2020 08:02:26 +0100
>>>> Subject: [PATCH] vhost: disable all features and trace last_avail_idx and
>>>>  ioctl calls
>>>>
>>>> ---
>>>>  drivers/vhost/net.c   | 20 +++++++++++++++++---
>>>>  drivers/vhost/vhost.c | 25 +++++++++++++++++++++++--
>>>>  drivers/vhost/vhost.h | 10 +++++-----
>>>>  3 files changed, 45 insertions(+), 10 deletions(-)
>>>>
>>>> diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
>>>> index e158159671fa..e4d5f843f9c0 100644
>>>> --- a/drivers/vhost/net.c
>>>> +++ b/drivers/vhost/net.c
>>>> @@ -1505,10 +1505,13 @@ static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
>>>>
>>>>       mutex_lock(&n->dev.mutex);
>>>>       r = vhost_dev_check_owner(&n->dev);
>>>> -     if (r)
>>>> +     if (r) {
>>>> +             pr_debug("vhost_dev_check_owner index=%u fd=%d rc r=%d", index, fd, r);
>>>>               goto err;
>>>> +     }
>>>>
>>>>       if (index >= VHOST_NET_VQ_MAX) {
>>>> +             pr_debug("vhost_dev_check_owner index=%u fd=%d MAX=%d", index, fd, VHOST_NET_VQ_MAX);
>>>>               r = -ENOBUFS;
>>>>               goto err;
>>>>       }
>>>> @@ -1518,22 +1521,26 @@ static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
>>>>
>>>>       /* Verify that ring has been setup correctly. */
>>>>       if (!vhost_vq_access_ok(vq)) {
>>>> +             pr_debug("vhost_net_set_backend index=%u fd=%d !vhost_vq_access_ok", index, fd);
>>>>               r = -EFAULT;
>>>>               goto err_vq;
>>>>       }
>>>>       sock = get_socket(fd);
>>>>       if (IS_ERR(sock)) {
>>>>               r = PTR_ERR(sock);
>>>> +             pr_debug("vhost_net_set_backend index=%u fd=%d get_socket err r=%d", index, fd, r);
>>>>               goto err_vq;
>>>>       }
>>>>
>>>>       /* start polling new socket */
>>>>       oldsock = vq->private_data;
>>>>       if (sock != oldsock) {
>>>> +             pr_debug("sock=%p != oldsock=%p index=%u fd=%d vq=%p", sock, oldsock, index, fd, vq);
>>>>               ubufs = vhost_net_ubuf_alloc(vq,
>>>>                                            sock && vhost_sock_zcopy(sock));
>>>>               if (IS_ERR(ubufs)) {
>>>>                       r = PTR_ERR(ubufs);
>>>> +                     pr_debug("ubufs index=%u fd=%d err r=%d vq=%p", index, fd, r, vq);
>>>>                       goto err_ubufs;
>>>>               }
>>>>
>>>> @@ -1541,11 +1548,15 @@ static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
>>>>               vq->private_data = sock;
>>>>               vhost_net_buf_unproduce(nvq);
>>>>               r = vhost_vq_init_access(vq);
>>>> -             if (r)
>>>> +             if (r) {
>>>> +                     pr_debug("init_access index=%u fd=%d r=%d vq=%p", index, fd, r, vq);
>>>>                       goto err_used;
>>>> +             }
>>>>               r = vhost_net_enable_vq(n, vq);
>>>> -             if (r)
>>>> +             if (r) {
>>>> +                     pr_debug("enable_vq index=%u fd=%d r=%d vq=%p", index, fd, r, vq);
>>>>                       goto err_used;
>>>> +             }
>>>>               if (index == VHOST_NET_VQ_RX)
>>>>                       nvq->rx_ring = get_tap_ptr_ring(fd);
>>>>
>>>> @@ -1559,6 +1570,8 @@ static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
>>>>
>>>>       mutex_unlock(&vq->mutex);
>>>>
>>>> +     pr_debug("sock=%p", sock);
>>>> +
>>>>       if (oldubufs) {
>>>>               vhost_net_ubuf_put_wait_and_free(oldubufs);
>>>>               mutex_lock(&vq->mutex);
>>>> @@ -1710,6 +1723,7 @@ static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
>>>>
>>>>       switch (ioctl) {
>>>>       case VHOST_NET_SET_BACKEND:
>>>> +             pr_debug("VHOST_NET_SET_BACKEND");
>>>>               if (copy_from_user(&backend, argp, sizeof backend))
>>>>                       return -EFAULT;
>>>>               return vhost_net_set_backend(n, backend.index, backend.fd);
>>>> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
>>>> index b5a51b1f2e79..ec25ba32fe81 100644
>>>> --- a/drivers/vhost/vhost.c
>>>> +++ b/drivers/vhost/vhost.c
>>>> @@ -1642,15 +1642,30 @@ long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *arg
>>>>                       r = -EINVAL;
>>>>                       break;
>>>>               }
>>>> +
>>>> +             if (vq->last_avail_idx || vq->avail_idx) {
>>>> +                     pr_debug(
>>>> +                             "strange VHOST_SET_VRING_BASE [vq=%p][s.index=%u][s.num=%u]",
>>>> +                             vq, s.index, s.num);
>>>> +                     dump_stack();
>>>> +                     r = 0;
>>>> +                     break;
>>>> +             }
>>>>               vq->last_avail_idx = s.num;
>>>>               /* Forget the cached index value. */
>>>>               vq->avail_idx = vq->last_avail_idx;
>>>> +             pr_debug(
>>>> +                     "VHOST_SET_VRING_BASE [vq=%p][vq->last_avail_idx=%u][vq->avail_idx=%u][s.index=%u][s.num=%u]",
>>>> +                     vq, vq->last_avail_idx, vq->avail_idx, s.index, s.num);
>>>>               break;
>>>>       case VHOST_GET_VRING_BASE:
>>>>               s.index = idx;
>>>>               s.num = vq->last_avail_idx;
>>>>               if (copy_to_user(argp, &s, sizeof s))
>>>>                       r = -EFAULT;
>>>> +             pr_debug(
>>>> +                     "VHOST_GET_VRING_BASE [vq=%p][vq->last_avail_idx=%u][vq->avail_idx=%u][s.index=%u][s.num=%u]",
>>>> +                     vq, vq->last_avail_idx, vq->avail_idx, s.index, s.num);
>>>>               break;
>>>>       case VHOST_SET_VRING_KICK:
>>>>               if (copy_from_user(&f, argp, sizeof f)) {
>>>> @@ -2239,8 +2254,8 @@ static int fetch_buf(struct vhost_virtqueue *vq)
>>>>               vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
>>>>
>>>>               if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) {
>>>> -                     vq_err(vq, "Guest moved used index from %u to %u",
>>>> -                             last_avail_idx, vq->avail_idx);
>>>> +                     vq_err(vq, "Guest moved vq %p used index from %u to %u",
>>>> +                             vq, last_avail_idx, vq->avail_idx);
>>>>                       return -EFAULT;
>>>>               }
>>>>
>>>> @@ -2316,6 +2331,9 @@ static int fetch_buf(struct vhost_virtqueue *vq)
>>>>       BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY));
>>>>
>>>>       /* On success, increment avail index. */
>>>> +     pr_debug(
>>>> +             "[vq=%p][vq->last_avail_idx=%u][vq->avail_idx=%u][vq->ndescs=%d][vq->first_desc=%d]",
>>>> +             vq, vq->last_avail_idx, vq->avail_idx, vq->ndescs, vq->first_desc);
>>>>       vq->last_avail_idx++;
>>>>
>>>>       return 0;
>>>> @@ -2432,6 +2450,9 @@ EXPORT_SYMBOL_GPL(vhost_get_vq_desc);
>>>>  /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
>>>>  void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n)
>>>>  {
>>>> +     pr_debug(
>>>> +             "DISCARD [vq=%p][vq->last_avail_idx=%u][vq->avail_idx=%u][n=%d]",
>>>> +             vq, vq->last_avail_idx, vq->avail_idx, n);
>>>>       vq->last_avail_idx -= n;
>>>>  }
>>>>  EXPORT_SYMBOL_GPL(vhost_discard_vq_desc);
>>>> diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
>>>> index 661088ae6dc7..08f6d2ccb697 100644
>>>> --- a/drivers/vhost/vhost.h
>>>> +++ b/drivers/vhost/vhost.h
>>>> @@ -250,11 +250,11 @@ int vhost_init_device_iotlb(struct vhost_dev *d, bool enabled);
>>>>       } while (0)
>>>>
>>>>  enum {
>>>> -     VHOST_FEATURES = (1ULL << VIRTIO_F_NOTIFY_ON_EMPTY) |
>>>> -                      (1ULL << VIRTIO_RING_F_INDIRECT_DESC) |
>>>> -                      (1ULL << VIRTIO_RING_F_EVENT_IDX) |
>>>> -                      (1ULL << VHOST_F_LOG_ALL) |
>>>> -                      (1ULL << VIRTIO_F_ANY_LAYOUT) |
>>>> +     VHOST_FEATURES = /* (1ULL << VIRTIO_F_NOTIFY_ON_EMPTY) | */
>>>> +                      /* (1ULL << VIRTIO_RING_F_INDIRECT_DESC) | */
>>>> +                      /* (1ULL << VIRTIO_RING_F_EVENT_IDX) | */
>>>> +                      /* (1ULL << VHOST_F_LOG_ALL) | */
>>>> +                      /* (1ULL << VIRTIO_F_ANY_LAYOUT) | */
>>>>                        (1ULL << VIRTIO_F_VERSION_1)
>>>>  };
>>>>
>>>>
>>>
>>

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