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Date: Mon, 28 Nov 2022 11:47:30 +0100
From: Stefano Garzarella <sgarzare@...hat.com>
To: Cindy Lu <lulu@...hat.com>
Cc: jasowang@...hat.com, mst@...hat.com, kvm@...r.kernel.org,
linux-kernel@...r.kernel.org,
virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
stable@...r.kernel.org
Subject: Re: [PATCH v2] vhost_vdpa: fix the crash in unmap a large memory
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.
>
>Fixes: 4c8cf31885f6 ("vhost: introduce vDPA-based backend")
>Signed-off-by: Cindy Lu <lulu@...hat.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_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
>+ 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
>
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