diff options
| author | Jia Jia <physicalmtea@gmail.com> | 2026-07-26 22:43:14 +0800 |
|---|---|---|
| committer | Michael S. Tsirkin <mst@redhat.com> | 2026-08-03 23:08:15 -0400 |
| commit | 42bc45df5905e2b7dccb72adaf7730f66cfbe03f (patch) | |
| tree | 13b18fe90e4a157cb66b5535c2d776584f33cfaa | |
| parent | 22598f55a4c2b510b3df5e69e563387a963222ae (diff) | |
vhost-scsi: reject feature changes after endpoint
vhost_scsi_setup_vq_cmds() runs from VHOST_SCSI_SET_ENDPOINT and allocates
each command's protection scatterlist array (prot_sgl) according to the
acknowledged VIRTIO_SCSI_F_T10_PI bit. The command pools are not rebuilt
when VHOST_SET_FEATURES changes that bit later.
Although virtio feature bits must not change after feature negotiation,
vhost_scsi_set_features() currently accepts such a request after the
endpoint is active and updates acked_features. Enabling T10-PI after
endpoint setup therefore leaves prot_sgl NULL while the I/O path follows
the new feature bit.
For a 129-page protection payload, vhost_scsi_mapal() passes the missing
first chunk to sg_alloc_table_chained():
sg_alloc_table_chained(table, 129, first_chunk=NULL,
nents_first_chunk=inline_sg_cnt)
sg_pool_index() then hits:
BUG_ON(nents > SG_CHUNK_SIZE); /* 129 > 128 */
The kernel reported the following call trace and register state:
Call Trace:
<TASK>
? __sg_alloc_table+0x1d8/0x250
? __pfx_vhost_run_work_list+0x10/0x10 [vhost]
sg_alloc_table_chained+0x59/0xf0
? __pfx_sg_pool_alloc+0x10/0x10
? vhost_scsi_calc_sgls.constprop.0+0x43/0x60 [vhost_scsi]
vhost_scsi_handle_vq+0xf02/0x1700 [vhost_scsi]
? __pfx_vhost_scsi_handle_vq+0x10/0x10 [vhost_scsi]
vhost_scsi_handle_kick+0x37/0x50 [vhost_scsi]
vhost_run_work_list+0x8e/0xd0 [vhost]
vhost_task_fn+0xe1/0x210
ret_from_fork+0x348/0x540
</TASK>
RIP: 0010:0x4
CR2 = 0x4
RSP: 0018:ffffc90000dbf940 EFLAGS: 00010202
RAX: ffffffff82396810 RBX: ffff88811dc28b80 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000820 RDI: 0000000000000081
VHOST_F_LOG_ALL is a vhost-specific runtime feature and remains the only
exception.
Reject changes to any feature other than VHOST_F_LOG_ALL while the
endpoint is active. This preserves the existing runtime log toggle while
preventing feature-dependent command resources and data-path state from
becoming inconsistent. Userspace must clear the endpoint before changing
any other negotiated feature and set the endpoint up again afterward.
Fixes: bf2d650391be ("vhost-scsi: Allocate T10 PI structs only when enabled")
Signed-off-by: Jia Jia <physicalmtea@gmail.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Message-ID: <20260726144314.1652934-1-physicalmtea@gmail.com>
| -rw-r--r-- | drivers/vhost/scsi.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c index aae1164e1ca9..7a1f39a327da 100644 --- a/drivers/vhost/scsi.c +++ b/drivers/vhost/scsi.c @@ -2227,6 +2227,7 @@ static int vhost_scsi_set_features(struct vhost_scsi *vs, u64 features) { struct vhost_virtqueue *vq; bool is_log, was_log; + u64 old_features; int i; if (features & ~VHOST_SCSI_FEATURES) @@ -2242,6 +2243,14 @@ static int vhost_scsi_set_features(struct vhost_scsi *vs, u64 features) if (!vs->dev.nvqs) goto out; + old_features = vs->vqs[0].vq.acked_features; + if (vs->vs_tpg && + ((features ^ old_features) & + ~(1ULL << VHOST_F_LOG_ALL))) { + mutex_unlock(&vs->dev.mutex); + return -EBUSY; + } + is_log = features & (1 << VHOST_F_LOG_ALL); /* * All VQs should have same feature. |