Re: [PATCH v2] vhost_vdpa: fix the crash in unmap a large memory

From: Cindy Lu
Date: Tue Nov 29 2022 - 20:39:31 EST

On Mon, 28 Nov 2022 at 18:47, Stefano Garzarella <sgarzare@xxxxxxxxxx> wrote:
>
> On Fri, Nov 25, 2022 at 10:23:17AM +0800, Cindy Lu wrote:
> >While testing in vIOMMU, sometimes guest will unmap very large memory,
> >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 83 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: 000000000000001b
> >[ 647.830083] RDX: 00000000080000ff RSI: 0000000000000001 RDI: ffff921793d10540
> >[ 647.831214] RBP: 0000000007fc0100 R08: ffffae5340c0bcd0 R09: 0000000000000003
> >[ 647.832388] R10: 0000007fc0100000 R11: 0000000000100000 R12: 00000000080000ff
> >[ 647.833668] R13: ffffae5340c0bcd0 R14: ffff921793d10590 R15: 0000008000100000
> >[ 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: 0000000000372ee0
> >[ 647.838107] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> >[ 647.839283] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> >[ 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 76 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: 00007f7734ef9f4f
> >[ 647.859713] RDX: 0000000000000048 RSI: 00007f772ec8f090 RDI: 0000000000000010
> >[ 647.860942] RBP: 00007f772ec8f1a0 R08: 0000000000000000 R09: 0000000000000000
> >[ 647.862206] R10: 0000000000000001 R11: 0000000000000293 R12: 0000000000000010
> >[ 647.863446] R13: 0000000000000002 R14: 0000000000000000 R15: ffffffff01100000
> >[ 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 ]---
>
> I think you can remove the part below this line.
>
> From here:
>
> >[ 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 83 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: 000000000000001b
> >[ 647.888775] RDX: 00000000080000ff RSI: 0000000000000001 RDI: ffff921793d10540
> >[ 647.890295] RBP: 0000000007fc0100 R08: ffffae5340c0bcd0 R09: 0000000000000003
> >[ 647.891660] R10: 0000007fc0100000 R11: 0000000000100000 R12: 00000000080000ff
> >[ 647.893019] R13: ffffae5340c0bcd0 R14: ffff921793d10590 R15: 0000008000100000
> >[ 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: 0000000000372ee0
> >[ 647.898719] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>
> To here.
>
> And maybe I would also remove the timestamps; in the end they are not
> useful for this fix and they crowd this trace.
>
thanks Stefano ，I will fix this
> >
> >Fixes: 4c8cf31885f6 ("vhost: introduce vDPA-based backend")
> >Signed-off-by: Cindy Lu <lulu@xxxxxxxxxx>
> >---
> > 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_vdpa *v,
> > struct vhost_iotlb_map *map;
> > struct page *page;
> > unsigned long pfn, pinned;
> >+ struct vdpa_device *vdpa = v->vdpa;
> >+ const struct vdpa_config_ops *ops = vdpa->config;
> >
> > while ((map = vhost_iotlb_itree_first(iotlb, start, last)) != NULL) {
> > pinned = PFN_DOWN(map->size);
> >@@ -703,6 +705,8 @@ static void vhost_vdpa_pa_unmap(struct vhost_vdpa *v,
> > unpin_user_page(page);
> > }
> > atomic64_sub(PFN_DOWN(map->size), &dev->mm->pinned_vm);
> >+ if ((ops->dma_map == NULL) && (ops->set_map == NULL))
> >+ iommu_unmap(v->domain, map->start, map->size);
> > 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 = v->vdpa;
> >+ const struct vdpa_config_ops *ops = vdpa->config;
> >
> > while ((map = vhost_iotlb_itree_first(iotlb, start, last)) != NULL) {
> > map_file = (struct vdpa_map_file *)map->opaque;
> > fput(map_file->file);
> > kfree(map_file);
> >+ if (ops->set_map == NULL)
>
> Should we check that `dma_map` is also NULL as in the previous hunk?
>
> Thanks,
> Stefano
>
Thanks Stefano, I wIll rewrite this part
> >+ iommu_unmap(v->domain, map->start, map->size);
> > 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 free
> >--
> >2.34.3
> >
>