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From:   Cindy Lu <lulu@redhat.com>
Date:   Wed, 30 Nov 2022 09:39:27 +0800
Message-ID: <CACLfguVJoe3oGM+NbECOaXZa7AkiJHjfK3-4cBLhLDvBpTf7CA@mail.gmail.com>
Subject: Re: [PATCH v3] vhost_vdpa: fix the crash in unmap a large memory
To:     Jason Wang <jasowang@redhat.com>
Cc:     mst@redhat.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
        virtualization@lists.linux-foundation.org, netdev@vger.kernel.org,
        stable@vger.kernel.org
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On Tue, 29 Nov 2022 at 11:04, Jason Wang <jasowang@redhat.com> wrote:
>
> On Fri, Nov 25, 2022 at 3:38 PM Cindy Lu <lulu@redhat.com> wrote:
> >
> > / and
> >
> >
> > On Fri, 25 Nov 2022 at 15:17, Jason Wang <jasowang@redhat.com> wrote:
> > >
> > > On Fri, Nov 25, 2022 at 10:31 AM Cindy Lu <lulu@redhat.com> wrote:
> > > >
> > > > While testing in vIOMMU, sometimes guest will unmap very large memo=
ry,
> > > > which will cause the crash. To fix this,Move the iommu_unmap to
> > > > vhost_vdpa_pa_unmap/vhost_vdpa_va_unmap and only unmap the memory
> > > > that saved in iotlb.
> > > >
> > > > Call Trace:
> > > > [  647.820144] ------------[ cut here ]------------
> > > > [  647.820848] kernel BUG at drivers/iommu/intel/iommu.c:1174!
> > > > [  647.821486] invalid opcode: 0000 [#1] PREEMPT SMP PTI
> > > > [  647.822082] CPU: 10 PID: 1181 Comm: qemu-system-x86 Not tainted =
6.0.0-rc1home_lulu_2452_lulu7_vhost+ #62
> > > > [  647.823139] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), =
BIOS rel-1.15.0-29-g6a62e0cb0dfe-prebuilt.qem4
> > > > [  647.824365] RIP: 0010:domain_unmap+0x48/0x110
> > > > [  647.825424] Code: 48 89 fb 8d 4c f6 1e 39 c1 0f 4f c8 83 e9 0c 8=
3 f9 3f 7f 18 48 89 e8 48 d3 e8 48 85 c0 75 59
> > > > [  647.828064] RSP: 0018:ffffae5340c0bbf0 EFLAGS: 00010202
> > > > [  647.828973] RAX: 0000000000000001 RBX: ffff921793d10540 RCX: 000=
000000000001b
> > > > [  647.830083] RDX: 00000000080000ff RSI: 0000000000000001 RDI: fff=
f921793d10540
> > > > [  647.831214] RBP: 0000000007fc0100 R08: ffffae5340c0bcd0 R09: 000=
0000000000003
> > > > [  647.832388] R10: 0000007fc0100000 R11: 0000000000100000 R12: 000=
00000080000ff
> > > > [  647.833668] R13: ffffae5340c0bcd0 R14: ffff921793d10590 R15: 000=
0008000100000
> > > > [  647.834782] FS:  00007f772ec90640(0000) GS:ffff921ce7a80000(0000=
) knlGS:0000000000000000
> > > > [  647.836004] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > > > [  647.836990] CR2: 00007f02c27a3a20 CR3: 0000000101b0c006 CR4: 000=
0000000372ee0
> > > > [  647.838107] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 000=
0000000000000
> > > > [  647.839283] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 000=
0000000000400
> > > > [  647.840666] Call Trace:
> > > > [  647.841437]  <TASK>
> > > > [  647.842107]  intel_iommu_unmap_pages+0x93/0x140
> > > > [  647.843112]  __iommu_unmap+0x91/0x1b0
> > > > [  647.844003]  iommu_unmap+0x6a/0x95
> > > > [  647.844885]  vhost_vdpa_unmap+0x1de/0x1f0 [vhost_vdpa]
> > > > [  647.845985]  vhost_vdpa_process_iotlb_msg+0xf0/0x90b [vhost_vdpa=
]
> > > > [  647.847235]  ? _raw_spin_unlock+0x15/0x30
> > > > [  647.848181]  ? _copy_from_iter+0x8c/0x580
> > > > [  647.849137]  vhost_chr_write_iter+0xb3/0x430 [vhost]
> > > > [  647.850126]  vfs_write+0x1e4/0x3a0
> > > > [  647.850897]  ksys_write+0x53/0xd0
> > > > [  647.851688]  do_syscall_64+0x3a/0x90
> > > > [  647.852508]  entry_SYSCALL_64_after_hwframe+0x63/0xcd
> > > > [  647.853457] RIP: 0033:0x7f7734ef9f4f
> > > > [  647.854408] Code: 89 54 24 18 48 89 74 24 10 89 7c 24 08 e8 29 7=
6 f8 ff 48 8b 54 24 18 48 8b 74 24 10 41 89 c8
> > > > [  647.857217] RSP: 002b:00007f772ec8f040 EFLAGS: 00000293 ORIG_RAX=
: 0000000000000001
> > > > [  647.858486] RAX: ffffffffffffffda RBX: 00000000fef00000 RCX: 000=
07f7734ef9f4f
> > > > [  647.859713] RDX: 0000000000000048 RSI: 00007f772ec8f090 RDI: 000=
0000000000010
> > > > [  647.860942] RBP: 00007f772ec8f1a0 R08: 0000000000000000 R09: 000=
0000000000000
> > > > [  647.862206] R10: 0000000000000001 R11: 0000000000000293 R12: 000=
0000000000010
> > > > [  647.863446] R13: 0000000000000002 R14: 0000000000000000 R15: fff=
fffff01100000
> > > > [  647.864692]  </TASK>
> > > > [  647.865458] Modules linked in: rpcsec_gss_krb5 auth_rpcgss nfsv4=
 dns_resolver nfs lockd grace fscache netfs v]
> > > > [  647.874688] ---[ end trace 0000000000000000 ]---
> > > > [  647.876013] RIP: 0010:domain_unmap+0x48/0x110
> > > > [  647.878306] Code: 48 89 fb 8d 4c f6 1e 39 c1 0f 4f c8 83 e9 0c 8=
3 f9 3f 7f 18 48 89 e8 48 d3 e8 48 85 c0 75 59
> > > > [  647.884581] RSP: 0018:ffffae5340c0bbf0 EFLAGS: 00010202
> > > > [  647.886308] RAX: 0000000000000001 RBX: ffff921793d10540 RCX: 000=
000000000001b
> > > > [  647.888775] RDX: 00000000080000ff RSI: 0000000000000001 RDI: fff=
f921793d10540
> > > > [  647.890295] RBP: 0000000007fc0100 R08: ffffae5340c0bcd0 R09: 000=
0000000000003
> > > > [  647.891660] R10: 0000007fc0100000 R11: 0000000000100000 R12: 000=
00000080000ff
> > > > [  647.893019] R13: ffffae5340c0bcd0 R14: ffff921793d10590 R15: 000=
0008000100000
> > > > [  647.894506] FS:  00007f772ec90640(0000) GS:ffff921ce7a80000(0000=
) knlGS:0000000000000000
> > > > [  647.895963] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > > > [  647.897348] CR2: 00007f02c27a3a20 CR3: 0000000101b0c006 CR4: 000=
0000000372ee0
> > > > [  647.898719] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 000=
0000000000000
> > > >
> > > > Cc: stable@vger.kernel.org
> > > > Fixes: 4c8cf31885f6 ("vhost: introduce vDPA-based backend")
> > > > Signed-off-by: Cindy Lu <lulu@redhat.com>
> > > > ---
> > > >  drivers/vhost/vdpa.c | 10 ++++++++--
> > > >  1 file changed, 8 insertions(+), 2 deletions(-)
> > > >
> > > > diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
> > > > index 166044642fd5..e5a07751bf45 100644
> > > > --- a/drivers/vhost/vdpa.c
> > > > +++ b/drivers/vhost/vdpa.c
> > > > @@ -692,6 +692,8 @@ static void vhost_vdpa_pa_unmap(struct vhost_vd=
pa *v,
> > > >         struct vhost_iotlb_map *map;
> > > >         struct page *page;
> > > >         unsigned long pfn, pinned;
> > > > +       struct vdpa_device *vdpa =3D v->vdpa;
> > > > +       const struct vdpa_config_ops *ops =3D vdpa->config;
> > > >
> > > >         while ((map =3D vhost_iotlb_itree_first(iotlb, start, last)=
) !=3D NULL) {
> > > >                 pinned =3D PFN_DOWN(map->size);
> > > > @@ -703,6 +705,8 @@ static void vhost_vdpa_pa_unmap(struct vhost_vd=
pa *v,
> > > >                         unpin_user_page(page);
> > > >                 }
> > > >                 atomic64_sub(PFN_DOWN(map->size), &dev->mm->pinned_=
vm);
> > > > +               if ((ops->dma_map =3D=3D NULL) && (ops->set_map =3D=
=3D NULL))
> > > > +                       iommu_unmap(v->domain, map->start, map->siz=
e);
> > >
> > > I think we'd better move the ops->dma_unmap() here as well as iommu_u=
nmap()?
> > >
> > > >                 vhost_iotlb_map_free(iotlb, map);
> > > >         }
> > > >  }
> > > > @@ -713,11 +717,15 @@ static void vhost_vdpa_va_unmap(struct vhost_=
vdpa *v,
> > > >  {
> > > >         struct vhost_iotlb_map *map;
> > > >         struct vdpa_map_file *map_file;
> > > > +       struct vdpa_device *vdpa =3D v->vdpa;
> > > > +       const struct vdpa_config_ops *ops =3D vdpa->config;
> > > >
> > > >         while ((map =3D vhost_iotlb_itree_first(iotlb, start, last)=
) !=3D NULL) {
> > > >                 map_file =3D (struct vdpa_map_file *)map->opaque;
> > > >                 fput(map_file->file);
> > > >                 kfree(map_file);
> > > > +               if (ops->set_map =3D=3D NULL)
> > > > +                       iommu_unmap(v->domain, map->start, map->siz=
e);
> > >
> > > Need to check where we have dma_unmap() and call that if it exists?
> > >
> > > Thanks
> > >
> > Hi Jason=EF=BC=8C
> > I think  these functions are called in vhost_vdpa_unmap,
> > Do you want to separate the function in vhost_vdpa_unmap
> > and move it to vhost_vdpa_va_unmap and vhost_vdpa_pa_unmap? I
>
> I meant dma_map()/dma_unmap() should be functional equivalent to
> iommu_map/unmap(). That means we should unmap exactly what is mapped
> before (vDPA parent may call iommu_unmap in its own dma_unmap() if it
> needs). If we move the iommu_unmap() from vhost_vdpa_unmap() to
> vhost_vdpa_{pa|va}_umap, we should move dma_unmap() as well.
>
> Thanks
>
Got it.thanks Jason, I will change this part
Thanks
Cindy

> > thanks
> > cindy
> >
> > > >                 vhost_iotlb_map_free(iotlb, map);
> > > >         }
> > > >  }
> > > > @@ -805,8 +813,6 @@ static void vhost_vdpa_unmap(struct vhost_vdpa =
*v,
> > > >         } else if (ops->set_map) {
> > > >                 if (!v->in_batch)
> > > >                         ops->set_map(vdpa, asid, iotlb);
> > > > -       } else {
> > > > -               iommu_unmap(v->domain, iova, size);
> > > >         }
> > > >
> > > >         /* If we are in the middle of batch processing, delay the f=
ree
> > > > --
> > > > 2.34.3
> > > >
> > >
> >
>