Age | Commit message (Collapse) | Author |
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Log write descriptors for the event queue, leveraging vhost_get_vq_desc()
to retrieve the array of write descriptors to obtain the log buffer.
There is only one path for event queue.
Suggested-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Reviewed-by: Mike Christie <michael.christie@oracle.com>
Message-Id: <20250403063028.16045-9-dongli.zhang@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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Log write descriptors for the control queue, leveraging
vhost_scsi_get_desc() and vhost_get_vq_desc() to retrieve the array of
write descriptors to obtain the log buffer.
For Task Management Requests, similar to the I/O queue, store the log
buffer during the submission path and log it in the completion or error
handling path.
For Asynchronous Notifications, only the submission path is involved.
Suggested-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Message-Id: <20250403063028.16045-8-dongli.zhang@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Mike Christie <michael.christie@oracle.com>
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Log write descriptors for the I/O queue, leveraging vhost_scsi_get_desc()
and vhost_get_vq_desc() to retrieve the array of write descriptors to
obtain the log buffer.
In addition, introduce a vhost-scsi specific function to log vring
descriptors. In this function, the 'partial' argument is set to false, and
the 'len' argument is set to 0, because vhost-scsi always logs all pages
shared by a vring descriptor. Add WARN_ON_ONCE() since vhost-scsi doesn't
support VIRTIO_F_ACCESS_PLATFORM.
The per-cmd log buffer is allocated on demand in the submission path after
VHOST_F_LOG_ALL is set. Return -ENOMEM on allocation failure, in order to
send SAM_STAT_TASK_SET_FULL to the guest.
It isn't reclaimed in the completion path. Instead, it is reclaimed when
VHOST_F_LOG_ALL is removed, or during VHOST_SCSI_SET_ENDPOINT when all
commands are destroyed.
Store the log buffer during the submission path and log it in the
completion path. Logging is also required in the error handling path of the
submission process.
Suggested-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Message-Id: <20250403063028.16045-7-dongli.zhang@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Mike Christie <michael.christie@oracle.com>
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Adjust vhost_scsi_get_desc() to facilitate logging of vring descriptors.
Add new arguments to allow passing the log buffer and length to
vhost_get_vq_desc().
In addition, reset 'log_num' since vhost_get_vq_desc() may reset it only
after certain condition checks.
Suggested-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Reviewed-by: Mike Christie <michael.christie@oracle.com>
Message-Id: <20250403063028.16045-6-dongli.zhang@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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Although the support of VIRTIO_F_ANY_LAYOUT + VIRTIO_F_VERSION_1 was
signaled by the commit 664ed90e621c ("vhost/scsi: Set
VIRTIO_F_ANY_LAYOUT + VIRTIO_F_VERSION_1 feature bits"),
vhost_scsi_send_bad_target() still assumes the response in a single
descriptor.
Similar issue in vhost_scsi_send_bad_target() has been fixed in previous
commit. In addition, similar issue for vhost_scsi_complete_cmd_work() has
been fixed by the commit 6dd88fd59da8 ("vhost-scsi: unbreak any layout for
response").
Fixes: 3ca51662f818 ("vhost-scsi: Add better resource allocation failure handling")
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Mike Christie <michael.christie@oracle.com>
Message-Id: <20250403063028.16045-4-dongli.zhang@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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Although the support of VIRTIO_F_ANY_LAYOUT + VIRTIO_F_VERSION_1 was
signaled by the commit 664ed90e621c ("vhost/scsi: Set
VIRTIO_F_ANY_LAYOUT + VIRTIO_F_VERSION_1 feature bits"),
vhost_scsi_send_bad_target() still assumes the response in a single
descriptor.
In addition, although vhost_scsi_send_bad_target() is used by both I/O
queue and control queue, the response header is always
virtio_scsi_cmd_resp. It is required to use virtio_scsi_ctrl_tmf_resp or
virtio_scsi_ctrl_an_resp for control queue.
Fixes: 664ed90e621c ("vhost/scsi: Set VIRTIO_F_ANY_LAYOUT + VIRTIO_F_VERSION_1 feature bits")
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Mike Christie <michael.christie@oracle.com>
Message-Id: <20250403063028.16045-3-dongli.zhang@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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The vhost-scsi completion path may access vq->log_base when vq->log_used is
already set to false.
vhost-thread QEMU-thread
vhost_scsi_complete_cmd_work()
-> vhost_add_used()
-> vhost_add_used_n()
if (unlikely(vq->log_used))
QEMU disables vq->log_used
via VHOST_SET_VRING_ADDR.
mutex_lock(&vq->mutex);
vq->log_used = false now!
mutex_unlock(&vq->mutex);
QEMU gfree(vq->log_base)
log_used()
-> log_write(vq->log_base)
Assuming the VMM is QEMU. The vq->log_base is from QEMU userpace and can be
reclaimed via gfree(). As a result, this causes invalid memory writes to
QEMU userspace.
The control queue path has the same issue.
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Mike Christie <michael.christie@oracle.com>
Message-Id: <20250403063028.16045-2-dongli.zhang@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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We have to save N iov entries to copy the virtio_scsi_cmd_resp struct
back to the guest's buffer. The difficulty is that we can't assume the
virtio_scsi_cmd_resp will be in 1 iov because older virtio specs allowed
you to break it up.
The worst case is that the guest was doing something like breaking up
the virtio_scsi_cmd_resp struct into 108 (the struct is 108 bytes)
byte sized vecs like:
iov[0].iov_base = ((unsigned char *)virtio_scsi_cmd_resp)[0]
iov[0].iov_len = 1
iov[1].iov_base = ((unsigned char *)virtio_scsi_cmd_resp)[1]
iov[1].iov_len = 1
....
iov[107].iov_base = ((unsigned char *)virtio_scsi_cmd_resp)[107]
iov[1].iov_len = 1
Right now we allocate UIO_MAXIOV vecs which is 1024 and so for a small
device with just 1 queue and 128 commands per queue, we are wasting
1.8 MB = (1024 current entries - 108) * 16 bytes per entry * 128 cmds
The most common case is going to be where the initiator puts the entire
virtio_scsi_cmd_resp in the first iov and does not split it. We've
always done it this way for Linux and the windows driver looks like
it's always done the same. It's highly unlikely anyone has ever split
the response and if they did it might just be where they have the
sense in a second iov but that doesn't seem likely as well.
So to optimize for the common implementation, this has us only
pre-allocate the single iovec. If we do hit the split up response case
this has us allocate the needed iovec when needed.
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Message-Id: <20241203191705.19431-9-michael.christie@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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It's extremely rare that we get unaligned requests that need to drop
down to the data copy code path. However, the iov_iter is almost 5% of
the mem used for the vhost_scsi_cmd. This patch has us allocate the
iov_iter only when needed since it's not a perf path that uses the
struct. This along with the patches that removed the duplicated fields on
the vhost_scsd_cmd allow us to reduce mem use by 1 MB in mid size setups
where we have 16 virtqueues and are doing 1024 cmds per queue.
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Message-Id: <20241203191705.19431-8-michael.christie@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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When setting up the command we will initially set values like lun and
data direction on the vhost scsi command. We then pass them to LIO which
stores them again on the LIO se_cmd. The se_cmd is actually stored in
the vhost scsi command so we are storing these values twice on the same
struct. So this patch has stop duplicating the storing of SCSI values
like lun, data dir, data len, cdb, etc on the vhost scsi command and
just pass them to LIO which will store them on the se_cmd.
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Message-Id: <20241203191705.19431-7-michael.christie@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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We currently preallocate scatterlists which have 2048 entries for each
command. For a small device with just 1 queue this results in:
8 MB = 32 bytes per sg * 2048 entries * 128 cmd
When mq is turned on and we increase the virtqueue_size so we can handle
commands from multiple queues in parallel, then this can sky rocket.
This patch allows us to dynamically allocate the scatterlist like is done
with drivers like NVMe and SCSI.
For small IO (4-16K) IOPs testing, we didn't see any regressions, but
for throughput testing we sometimes saw a 2-5% regression when the
backend device was very fast (8 NVMe drives in a MD RAID0 config or a
memory backed device). As a result this patch makes the dynamic
allocation feature a modparam so userspace can decide how it wants to
balance mem use and perf.
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Message-Id: <20241203191705.19431-6-michael.christie@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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This has us return queue full if we can't allocate a page during the
copy operation so the initiator can retry.
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Message-Id: <20241203191705.19431-5-michael.christie@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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If we can't allocate mem to map in data for a request or can't find
a tag for a command, we currently drop the command. This leads to the
error handler running to clean it up. Instead of dropping the command
this has us return an error telling the initiator that it queued more
commands than we can handle. The initiator will then reduce how many
commands it will send us and retry later.
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Message-Id: <20241203191705.19431-4-michael.christie@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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T10 PI is not a widely used feature. This has us only allocate the
structs for it if the feature has been enabled. For a common small setup
where you have 1 virtqueue and 128 commands per queue, this saves:
8MB = 32 bytes per sg * 2048 entries * 128 commands
per vhost-scsi device.
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Message-Id: <20241203191705.19431-3-michael.christie@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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Each worker thread can process 1 command at a time so there's no need to
allocate a upages array per cmd. This patch moves it to per queue. Even a
small device with 128 cmds and 1 queue this brings mem use for the array
from
2 MB = 8 bytes per page pointer * 2048 pointers * 128 cmds
to
16K = 8 bytes per pointer * 2048 * 1 queue
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Message-Id: <20241203191705.19431-2-michael.christie@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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If vhost_scsi_set_endpoint is called multiple times without a
vhost_scsi_clear_endpoint between them, we can hit multiple bugs
found by Haoran Zhang:
1. Use-after-free when no tpgs are found:
This fixes a use after free that occurs when vhost_scsi_set_endpoint is
called more than once and calls after the first call do not find any
tpgs to add to the vs_tpg. When vhost_scsi_set_endpoint first finds
tpgs to add to the vs_tpg array match=true, so we will do:
vhost_vq_set_backend(vq, vs_tpg);
...
kfree(vs->vs_tpg);
vs->vs_tpg = vs_tpg;
If vhost_scsi_set_endpoint is called again and no tpgs are found
match=false so we skip the vhost_vq_set_backend call leaving the
pointer to the vs_tpg we then free via:
kfree(vs->vs_tpg);
vs->vs_tpg = vs_tpg;
If a scsi request is then sent we do:
vhost_scsi_handle_vq -> vhost_scsi_get_req -> vhost_vq_get_backend
which sees the vs_tpg we just did a kfree on.
2. Tpg dir removal hang:
This patch fixes an issue where we cannot remove a LIO/target layer
tpg (and structs above it like the target) dir due to the refcount
dropping to -1.
The problem is that if vhost_scsi_set_endpoint detects a tpg is already
in the vs->vs_tpg array or if the tpg has been removed so
target_depend_item fails, the undepend goto handler will do
target_undepend_item on all tpgs in the vs_tpg array dropping their
refcount to 0. At this time vs_tpg contains both the tpgs we have added
in the current vhost_scsi_set_endpoint call as well as tpgs we added in
previous calls which are also in vs->vs_tpg.
Later, when vhost_scsi_clear_endpoint runs it will do
target_undepend_item on all the tpgs in the vs->vs_tpg which will drop
their refcount to -1. Userspace will then not be able to remove the tpg
and will hang when it tries to do rmdir on the tpg dir.
3. Tpg leak:
This fixes a bug where we can leak tpgs and cause them to be
un-removable because the target name is overwritten when
vhost_scsi_set_endpoint is called multiple times but with different
target names.
The bug occurs if a user has called VHOST_SCSI_SET_ENDPOINT and setup
a vhost-scsi device to target/tpg mapping, then calls
VHOST_SCSI_SET_ENDPOINT again with a new target name that has tpgs we
haven't seen before (target1 has tpg1 but target2 has tpg2). When this
happens we don't teardown the old target tpg mapping and just overwrite
the target name and the vs->vs_tpg array. Later when we do
vhost_scsi_clear_endpoint, we are passed in either target1 or target2's
name and we will only match that target's tpgs when we loop over the
vs->vs_tpg. We will then return from the function without doing
target_undepend_item on the tpgs.
Because of all these bugs, it looks like being able to call
vhost_scsi_set_endpoint multiple times was never supported. The major
user, QEMU, already has checks to prevent this use case. So to fix the
issues, this patch prevents vhost_scsi_set_endpoint from being called
if it's already successfully added tpgs. To add, remove or change the
tpg config or target name, you must do a vhost_scsi_clear_endpoint
first.
Fixes: 25b98b64e284 ("vhost scsi: alloc cmds per vq instead of session")
Fixes: 4f7f46d32c98 ("tcm_vhost: Use vq->private_data to indicate if the endpoint is setup")
Reported-by: Haoran Zhang <wh1sper@zju.edu.cn>
Closes: https://lore.kernel.org/virtualization/e418a5ee-45ca-4d18-9b5d-6f8b6b1add8e@oracle.com/T/#me6c0041ce376677419b9b2563494172a01487ecb
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20250129210922.121533-1-michael.christie@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Stefano Garzarella <sgarzare@redhat.com>
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Pull virtio fixes from Michael Tsirkin:
"Several small bugfixes all over the place.
Most notably, fixes the vsock allocation with GFP_KERNEL in atomic
context, which has been triggering warnings for lots of testers"
* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost:
vhost/scsi: null-ptr-dereference in vhost_scsi_get_req()
vsock/virtio: use GFP_ATOMIC under RCU read lock
virtio_console: fix misc probe bugs
virtio_ring: tag event_triggered as racy for KCSAN
vdpa/octeon_ep: Fix format specifier for pointers in debug messages
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Since commit 3f8ca2e115e5 ("vhost/scsi: Extract common handling code
from control queue handler") a null pointer dereference bug can be
triggered when guest sends an SCSI AN request.
In vhost_scsi_ctl_handle_vq(), `vc.target` is assigned with
`&v_req.tmf.lun[1]` within a switch-case block and is then passed to
vhost_scsi_get_req() which extracts `vc->req` and `tpg`. However, for
a `VIRTIO_SCSI_T_AN_*` request, tpg is not required, so `vc.target` is
set to NULL in this branch. Later, in vhost_scsi_get_req(),
`vc->target` is dereferenced without being checked, leading to a null
pointer dereference bug. This bug can be triggered from guest.
When this bug occurs, the vhost_worker process is killed while holding
`vq->mutex` and the corresponding tpg will remain occupied
indefinitely.
Below is the KASAN report:
Oops: general protection fault, probably for non-canonical address
0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 1 PID: 840 Comm: poc Not tainted 6.10.0+ #1
Hardware name: QEMU Ubuntu 24.04 PC (i440FX + PIIX, 1996), BIOS
1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:vhost_scsi_get_req+0x165/0x3a0
Code: 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 2b 02 00 00
48 b8 00 00 00 00 00 fc ff df 4d 8b 65 30 4c 89 e2 48 c1 ea 03 <0f> b6
04 02 4c 89 e2 83 e2 07 38 d0 7f 08 84 c0 0f 85 be 01 00 00
RSP: 0018:ffff888017affb50 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: ffff88801b000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff888017affcb8
RBP: ffff888017affb80 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: ffff888017affc88 R14: ffff888017affd1c R15: ffff888017993000
FS: 000055556e076500(0000) GS:ffff88806b100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000200027c0 CR3: 0000000010ed0004 CR4: 0000000000370ef0
Call Trace:
<TASK>
? show_regs+0x86/0xa0
? die_addr+0x4b/0xd0
? exc_general_protection+0x163/0x260
? asm_exc_general_protection+0x27/0x30
? vhost_scsi_get_req+0x165/0x3a0
vhost_scsi_ctl_handle_vq+0x2a4/0xca0
? __pfx_vhost_scsi_ctl_handle_vq+0x10/0x10
? __switch_to+0x721/0xeb0
? __schedule+0xda5/0x5710
? __kasan_check_write+0x14/0x30
? _raw_spin_lock+0x82/0xf0
vhost_scsi_ctl_handle_kick+0x52/0x90
vhost_run_work_list+0x134/0x1b0
vhost_task_fn+0x121/0x350
...
</TASK>
---[ end trace 0000000000000000 ]---
Let's add a check in vhost_scsi_get_req.
Fixes: 3f8ca2e115e5 ("vhost/scsi: Extract common handling code from control queue handler")
Signed-off-by: Haoran Zhang <wh1sper@zju.edu.cn>
[whitespace fixes]
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Message-Id: <b26d7ddd-b098-4361-88f8-17ca7f90adf7@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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asm/unaligned.h is always an include of asm-generic/unaligned.h;
might as well move that thing to linux/unaligned.h and include
that - there's nothing arch-specific in that header.
auto-generated by the following:
for i in `git grep -l -w asm/unaligned.h`; do
sed -i -e "s/asm\/unaligned.h/linux\/unaligned.h/" $i
done
for i in `git grep -l -w asm-generic/unaligned.h`; do
sed -i -e "s/asm-generic\/unaligned.h/linux\/unaligned.h/" $i
done
git mv include/asm-generic/unaligned.h include/linux/unaligned.h
git mv tools/include/asm-generic/unaligned.h tools/include/linux/unaligned.h
sed -i -e "/unaligned.h/d" include/asm-generic/Kbuild
sed -i -e "s/__ASM_GENERIC/__LINUX/" include/linux/unaligned.h tools/include/linux/unaligned.h
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vhost_vq_work_queue will never fail when queueing the TMF's response
handling because a guest can only send us TMFs when the device is fully
setup so there is always a worker at that time. In the next patches we
will modify the worker code so it handles SIGKILL by exiting before
outstanding commands/TMFs have sent their responses. In that case
vhost_vq_work_queue can fail when we try to send a response.
This has us just free the TMF's resources since at this time the guest
won't be able to get a response even if we could send it.
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Message-Id: <20240316004707.45557-6-michael.christie@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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We flush all the workers that are not also used by the ctl vq to make
sure that responses queued by LIO before the TMF response are sent
before the TMF response. This requires a special vhost_vq_flush
function which, in the next patches where we handle SIGKILL killing
workers while in use, will require extra locking/complexity. To avoid
that, this patch has us flush the entire device from the system work
queue, then queue up sending the response from there.
This is a little less optimal since we now flush all workers but this
will be ok since commands have already timed out and perf is not a
concern.
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Message-Id: <20240316004707.45557-4-michael.christie@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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In the next patches we will support the vhost_task being killed while in
use. The problem for vhost-scsi is that we can't free some structs until
we get responses for commands we have submitted to the target layer and
we currently process the responses from the vhost_task.
This has just drop the responses and free the command's resources. When
all commands have completed then operations like flush will be woken up
and we can complete device release and endpoint cleanup.
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Message-Id: <20240316004707.45557-3-michael.christie@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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Currently, we can try to queue an event's work before the vhost_task is
created. When this happens we just drop it in vhost_scsi_do_plug before
even calling vhost_vq_work_queue. During a device shutdown we do the
same thing after vhost_scsi_clear_endpoint has cleared the backends.
In the next patches we will be able to kill the vhost_task before we
have cleared the endpoint. In that case, vhost_vq_work_queue can fail
and we will leak the event's memory. This has handle the failure by
just freeing the event. This is safe to do, because
vhost_vq_work_queue will only return failure for us when the vhost_task
is killed and so userspace will not be able to handle events if we
sent them.
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Message-Id: <20240316004707.45557-2-michael.christie@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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Pull virtio updates from Michael Tsirkin:
"vhost,virtio,vdpa: features, fixes, cleanups.
vdpa/mlx5:
- VHOST_BACKEND_F_ENABLE_AFTER_DRIVER_OK
- new maintainer
vdpa:
- support for vq descriptor mappings
- decouple reset of iotlb mapping from device reset
and fixes, cleanups all over the place"
* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost: (34 commits)
vdpa_sim: implement .reset_map support
vdpa/mlx5: implement .reset_map driver op
vhost-vdpa: clean iotlb map during reset for older userspace
vdpa: introduce .compat_reset operation callback
vhost-vdpa: introduce IOTLB_PERSIST backend feature bit
vhost-vdpa: reset vendor specific mapping to initial state in .release
vdpa: introduce .reset_map operation callback
virtio_pci: add check for common cfg size
virtio-blk: fix implicit overflow on virtio_max_dma_size
virtio_pci: add build offset check for the new common cfg items
virtio: add definition of VIRTIO_F_NOTIF_CONFIG_DATA feature bit
vduse: make vduse_class constant
vhost-scsi: Spelling s/preceeding/preceding/g
virtio: kdoc for struct virtio_pci_modern_device
vdpa: Update sysfs ABI documentation
MAINTAINERS: Add myself as mlx5_vdpa driver
virtio-balloon: correct the comment of virtballoon_migratepage()
mlx5_vdpa: offer VHOST_BACKEND_F_ENABLE_AFTER_DRIVER_OK
vdpa/mlx5: Update cvq iotlb mapping on ASID change
vdpa/mlx5: Make iotlb helper functions more generic
...
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Fix a misspelling of "preceding".
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Message-Id: <b57b882675809f1f9dacbf42cf6b920b2bea9cba.1695903476.git.geert+renesas@glider.be>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
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This allows userspace to request the fabric drivers do direct submissions
if they support it. With the new device file, submit_type, users can
write 0 - 2 to control how commands are submitted to the backend:
0 - TARGET_FABRIC_DEFAULT_SUBMIT - LIO will use the fabric's default
submission type. This is the default for compat.
1 - TARGET_DIRECT_SUBMIT - LIO will submit the cmd to the backend from the
calling context if the fabric the cmd was received on supports it,
else it will use the fabric's default type.
2 - TARGET_QUEUE_SUBMIT - LIO will queue the cmd to the LIO submission
workqueue which will pass it to the backend.
When using an NVMe drive and vhost-scsi with direct submission we see
around a 20% improvement in 4K I/Os:
fio jobs 1 2 4 8 10
--------------------------------------------------
defer 94K 190K 394K 770K 890K
direct 128K 252K 488K 950K -
And when using the queueing mode, we now no longer see issues like where
the iSCSI tx thread is blocked in the block layer waiting on a tag so it
can't respond to a nop or perform I/Os for other LUs.
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Link: https://lore.kernel.org/r/20230928020907.5730-6-michael.christie@oracle.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
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In some cases, like with multiple LUN targets or where the target has to
respond to transport level requests from the receiving context it can be
better to defer cmd submission to a helper thread. If the backend driver
blocks on something like request/tag allocation it can block the entire
target submission path and other LUs and transport IO on that session.
In other cases like single LUN targets with storage that can support all
the commands that the target can queue, then it's best to submit the cmd
to the backend from the target's cmd receiving context.
Subsequent commits will allow the user to config what they prefer, but
drivers like loop can't directly submit because they can be called from a
context that can't sleep. And, drivers like vhost-scsi can support direct
submission, but need to keep their default behavior of deferring execution
to avoid possible regressions where the backend can block.
Make the drivers tell LIO core if they support direct submissions and their
current default, so we can prevent users from misconfiguring the system and
initialize devices correctly.
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Link: https://lore.kernel.org/r/20230928020907.5730-2-michael.christie@oracle.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
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Rename vhost_scsi_iov_to_sgl to vhost_scsi_map_iov_to_sgl so it matches
matches the naming style used for vhost_scsi_copy_iov_to_sgl.
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Message-Id: <20230709202859.138387-3-michael.christie@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
|
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The linux block layer requires bios/requests to have lengths with a 512
byte alignment. Some drivers/layers like dm-crypt and the directi IO code
will test for it and just fail. Other drivers like SCSI just assume the
requirement is met and will end up in infinte retry loops. The problem
for drivers like SCSI is that it uses functions like blk_rq_cur_sectors
and blk_rq_sectors which divide the request's length by 512. If there's
lefovers then it just gets dropped. But other code in the block/scsi
layer may use blk_rq_bytes/blk_rq_cur_bytes and end up thinking there is
still data left and try to retry the cmd. We can then end up getting
stuck in retry loops where part of the block/scsi thinks there is data
left, but other parts think we want to do IOs of zero length.
Linux will always check for alignment, but windows will not. When
vhost-scsi then translates the iovec it gets from a windows guest to a
scatterlist, we can end up with sg items where the sg->length is not
divisible by 512 due to the misaligned offset:
sg[0].offset = 255;
sg[0].length = 3841;
sg...
sg[N].offset = 0;
sg[N].length = 255;
When the lio backends then convert the SG to bios or other iovecs, we
end up sending them with the same misaligned values and can hit the
issues above.
This just has us drop down to allocating a temp page and copying the data
when we detect a misaligned buffer and the IO is large enough that it
will get split into multiple bad IOs.
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Message-Id: <20230709202859.138387-2-michael.christie@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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This has vhost-scsi support the worker ioctls by calling the
vhost_worker_ioctl helper.
With a single worker, the single thread becomes a bottlneck when trying
to use 3 or more virtqueues like:
fio --filename=/dev/sdb --direct=1 --rw=randrw --bs=4k \
--ioengine=libaio --iodepth=128 --numjobs=3
With the patches and doing a worker per vq, we can scale to at least
16 vCPUs/vqs (that's my system limit) with the same command fio command
above with numjobs=16:
fio --filename=/dev/sdb --direct=1 --rw=randrw --bs=4k \
--ioengine=libaio --iodepth=64 --numjobs=16
which gives around 2002K IOPs.
Note that for testing I dropped depth to 64 above because the vhost/virt
layer supports only 1024 total commands per device. And the only tuning I
did was set LIO's emulate_pr to 0 to avoid LIO's PR lock in the main IO
path which becomes an issue at around 12 jobs/virtqueues.
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Message-Id: <20230626232307.97930-17-michael.christie@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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With one worker we will always send the scsi cmd responses then send the
TMF rsp, because LIO will always complete the scsi cmds first then call
into us to send the TMF response.
With multiple workers, the IO vq workers could be running while the
TMF/ctl vq worker is running so this has us do a flush before completing
the TMF to make sure cmds are completed when it's work is later queued
and run.
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Message-Id: <20230626232307.97930-12-michael.christie@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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Convert from vhost_work_queue to vhost_vq_work_queue so we can
remove vhost_work_queue.
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Message-Id: <20230626232307.97930-11-michael.christie@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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This patch separates the scsi cmd completion code paths so we can complete
cmds based on their vq instead of having all cmds complete on the same
worker/CPU. This will be useful with the next patches that allow us to
create mulitple worker threads and bind them to different vqs, and we can
have completions running on different threads/CPUs.
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20230626232307.97930-10-michael.christie@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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Pull virtio updates from Michael Tsirkin:
"virtio,vhost,vdpa: features, fixes, and cleanups:
- reduction in interrupt rate in virtio
- perf improvement for VDUSE
- scalability for vhost-scsi
- non power of 2 ring support for packed rings
- better management for mlx5 vdpa
- suspend for snet
- VIRTIO_F_NOTIFICATION_DATA
- shared backend with vdpa-sim-blk
- user VA support in vdpa-sim
- better struct packing for virtio
and fixes, cleanups all over the place"
* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost: (52 commits)
vhost_vdpa: fix unmap process in no-batch mode
MAINTAINERS: make me a reviewer of VIRTIO CORE AND NET DRIVERS
tools/virtio: fix build caused by virtio_ring changes
virtio_ring: add a struct device forward declaration
vdpa_sim_blk: support shared backend
vdpa_sim: move buffer allocation in the devices
vdpa/snet: use likely/unlikely macros in hot functions
vdpa/snet: implement kick_vq_with_data callback
virtio-vdpa: add VIRTIO_F_NOTIFICATION_DATA feature support
virtio: add VIRTIO_F_NOTIFICATION_DATA feature support
vdpa/snet: support the suspend vDPA callback
vdpa/snet: support getting and setting VQ state
MAINTAINERS: add vringh.h to Virtio Core and Net Drivers
vringh: address kdoc warnings
vdpa: address kdoc warnings
virtio_ring: don't update event idx on get_buf
vdpa_sim: add support for user VA
vdpa_sim: replace the spinlock with a mutex to protect the state
vdpa_sim: use kthread worker
vdpa_sim: make devices agnostic for work management
...
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Pull SCSI updates from James Bottomley:
"Updates to the usual drivers (megaraid_sas, scsi_debug, lpfc, target,
mpi3mr, hisi_sas, arcmsr).
The major core change is the constification of the host templates
(which touches everything) along with other minor fixups and clean
ups"
* tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: (207 commits)
scsi: ufs: mcq: Use pointer arithmetic in ufshcd_send_command()
scsi: ufs: mcq: Annotate ufshcd_inc_sq_tail() appropriately
scsi: cxlflash: s/semahpore/semaphore/
scsi: lpfc: Silence an incorrect device output
scsi: mpi3mr: Use IRQ save variants of spinlock to protect chain frame allocation
scsi: scsi_debug: Fix missing error code in scsi_debug_init()
scsi: hisi_sas: Work around build failure in suspend function
scsi: lpfc: Fix ioremap issues in lpfc_sli4_pci_mem_setup()
scsi: mpt3sas: Fix an issue when driver is being removed
scsi: mpt3sas: Remove HBA BIOS version in the kernel log
scsi: target: core: Fix invalid memory access
scsi: scsi_debug: Drop sdebug_queue
scsi: scsi_debug: Only allow sdebug_max_queue be modified when no shosts
scsi: scsi_debug: Use scsi_host_busy() in delay_store() and ndelay_store()
scsi: scsi_debug: Use blk_mq_tagset_busy_iter() in stop_all_queued()
scsi: scsi_debug: Use blk_mq_tagset_busy_iter() in sdebug_blk_mq_poll()
scsi: scsi_debug: Dynamically allocate sdebug_queued_cmd
scsi: scsi_debug: Use scsi_block_requests() to block queues
scsi: scsi_debug: Protect block_unblock_all_queues() with mutex
scsi: scsi_debug: Change shost list lock to a mutex
...
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Pull ITER_UBUF updates from Jens Axboe:
"This turns singe vector imports into ITER_UBUF, rather than
ITER_IOVEC.
The former is more trivial to iterate and advance, and hence a bit
more efficient. From some very unscientific testing, ~60% of all iovec
imports are single vector"
* tag 'iter-ubuf.2-2023-04-21' of git://git.kernel.dk/linux:
iov_iter: Mark copy_compat_iovec_from_user() noinline
iov_iter: import single vector iovecs as ITER_UBUF
iov_iter: convert import_single_range() to ITER_UBUF
iov_iter: overlay struct iovec and ubuf/len
iov_iter: set nr_segs = 1 for ITER_UBUF
iov_iter: remove iov_iter_iovec()
iov_iter: add iter_iov_addr() and iter_iov_len() helpers
ALSA: pcm: check for user backed iterator, not specific iterator type
IB/qib: check for user backed iterator, not specific iterator type
IB/hfi1: check for user backed iterator, not specific iterator type
iov_iter: add iter_iovec() helper
block: ensure bio_alloc_map_data() deals with ITER_UBUF correctly
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We on longer need to hold the vhost_scsi_mutex the entire time we
set/clear the endpoint. The tv_tpg_mutex handles tpg accesses not related
to the tpg list, the port link/unlink functions use the tv_tpg_mutex while
accessing the tpg->vhost_scsi pointer, vhost_scsi_do_plug will no longer
queue events after the virtqueue's backend has been cleared and flushed,
and we don't drop our refcount to the tpg until after we have stopped
cmds and wait for outstanding cmds to complete.
This moves the vhost_scsi_mutex use to it's documented use of being used
to access the tpg list. We then don't need to hold it while a flush is
being performed causing other device's vhost_scsi_set_endpoint
and vhost_scsi_make_tpg/vhost_scsi_drop_tpg calls to have to wait on a
flakey device.
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Message-Id: <20230321020624.13323-8-michael.christie@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
|
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We are using the vhost_scsi_mutex to make sure vhost_scsi_port_link and
vhost_scsi_port_unlink see if vhost_scsi_clear_endpoint has cleared
tpg->vhost_scsi and it can't be freed while they are using.
However, we currently set the tpg->vhost_scsi pointer while holding
tv_tpg_mutex. So, we can just hold that while calling
vhost_scsi_hotplug/hotunplug. We then don't need to hold the
vhost_scsi_mutex while vhost_scsi_clear_endpoint is holding it and doing
a flush which could cause the LUN map/unmap to have to wait on another
device's flush.
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Message-Id: <20230321020624.13323-7-michael.christie@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
|
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We currenly hold the vhost_scsi_mutex while clearing the endpoint and
while performing vhost_scsi_do_plug, so tpg->vhost_scsi can't be freed
from uder us, and to make sure anything queued is handled by the
full call in vhost_scsi_clear_endpoint.
This patch removes the need for the vhost_scsi_mutex for the latter
case. In the next patches, we won't hold the vhost_scsi_mutex while
flushing so this patch adds a check for the clearing of the virtqueue
from vhost_scsi_clear_endpoint. We then know that once
vhost_scsi_clear_endpoint has cleared the backend that no new events
will be queued, and the flush after the vhost_vq_set_backend(vq, NULL)
call will see everything that's been queued to that point. So the flush
will then handle all events without the need for the vhost_scsi_mutex.
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Message-Id: <20230321020624.13323-6-michael.christie@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
|
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We don't need the device mutex in vhost_scsi_do_plug because:
1. we have the vhost_scsi_mutex so the tpg->vhost_scsi pointer will not
change on us and the vhost_scsi can't be freed from under us if it was
set.
2. vhost_scsi_clear_endpoint will stop the virtqueues and flush them while
holding the vhost_scsi_mutex so we know once vhost_scsi_clear_endpoint
has completed that vhost_scsi_do_plug can't send new events and any
queued ones have completed.
So this patch drops the device mutex use in vhost_scsi_do_plug.
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Message-Id: <20230321020624.13323-5-michael.christie@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
|
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We currently hold the vhost_scsi_mutex the entire time we are running
vhost_scsi_clear_endpoint. One of the reasons for this is that it prevents
userspace from being able to free the se_tpg from under us after we have
called target_undepend_item. However, it forces management operations for
for other devices to have to wait on a flakey device's:
vhost_scsi_clear_endpoint -> vhost_scsi_flush()
call which can which can take a long time.
This moves the target_undepend_item call and the tpg unsetup code to after
we have stopped new IO from starting up and after we have waited on
running IO. We can then release our refcount on the tpg and session
knowing our device is no longer accessing them. We can then drop the
vhost_scsi_mutex use during thee flush call in later patches in this set,
when we have removed other reasons for holding it.
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Message-Id: <20230321020624.13323-4-michael.christie@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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We normally clear the endpoint then unmap LUNs so the devices are fully
shutdown when the LUN is unmapped, but it's legal to unmap before
clearing. If the user does that while TMFs are running then we can end
up crashing.
vhost_scsi_port_unlink assumes that the LUN's tmf struct will always be on
the tmf_queue list. However, if a TMF is running then it will have been
removed while it's executing. If we do a LUN unmap at this time, then
we assume the entry is on the list and just start accessing it and free
it.
This fixes the bug by just allocating the vhost_scsi_tmf struct when it's
needed like is done with the se_tmr struct that's needed when we submit
the TMF. In this path perf is not an issue and we can use GFP_KERNEL
since it won't swing directly back on us, so we don't need to preallocate
the struct.
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Message-Id: <20230321020624.13323-3-michael.christie@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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If vhost_scsi_setup_vq_cmds fails we leave the tpg->vhost_scsi pointer
set. If the device is freed and then the user unmaps the LUN, the call to
vhost_scsi_port_unlink -> vhost_scsi_hotunplug will see the that
tpg->vhost_scsi is still set and try to use it.
This has us clear the vhost_scsi pointer in the failure path. It also
has us take tv_tpg_mutex in this failure path, because tv_tpg_vhost_count
is accessed under this mutex in vhost_scsi_drop_nexus and in the future
we will want to serialize access to tpg->vhost_scsi with that mutex
instead of the vhost_scsi_mutex.
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Message-Id: <20230321020624.13323-2-michael.christie@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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This returns a pointer to the current iovec entry in the iterator. Only
useful with ITER_IOVEC right now, but it prepares us to treat ITER_UBUF
and ITER_IOVEC identically for the first segment.
Rename struct iov_iter->iov to iov_iter->__iov to find any potentially
troublesome spots, and also to prevent anyone from adding new code that
accesses iter->iov directly.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
Remove callouts that are identical to the default implementations in TCM
Core.
Signed-off-by: Dmitry Bogdanov <d.bogdanov@yadro.com>
Link: https://lore.kernel.org/r/20230313181110.20566-9-d.bogdanov@yadro.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
|
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Follow the advice of the Documentation/filesystems/sysfs.rst
and show() should only use sysfs_emit() or sysfs_emit_at()
when formatting the value to be returned to user space.
Signed-off-by: Bo Liu <liubo03@inspur.com>
Message-Id: <20230129091145.2837-1-liubo03@inspur.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
|
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Al Viro said:
"""
Since "vhost/scsi: fix reuse of &vq->iov[out] in response"
we have this:
cmd->tvc_resp_iov = vq->iov[vc.out];
cmd->tvc_in_iovs = vc.in;
combined with
iov_iter_init(&iov_iter, ITER_DEST, &cmd->tvc_resp_iov,
cmd->tvc_in_iovs, sizeof(v_rsp));
in vhost_scsi_complete_cmd_work(). We used to have ->tvc_resp_iov
_pointing_ to vq->iov[vc.out]; back then iov_iter_init() asked to
set an iovec-backed iov_iter over the tail of vq->iov[], with
length being the amount of iovecs in the tail.
Now we have a copy of one element of that array. Fortunately, the members
following it in the containing structure are two non-NULL kernel pointers,
so copy_to_iter() will not copy anything beyond the first iovec - kernel
pointer is not (on the majority of architectures) going to be accepted by
access_ok() in copyout() and it won't be skipped since the "length" (in
reality - another non-NULL kernel pointer) won't be zero.
So it's not going to give a guest-to-qemu escalation, but it's definitely
a bug. Frankly, my preference would be to verify that the very first iovec
is long enough to hold rsp_size. Due to the above, any users that try to
give us vq->iov[vc.out].iov_len < sizeof(struct virtio_scsi_cmd_resp)
would currently get a failure in vhost_scsi_complete_cmd_work()
anyway.
"""
However, the spec doesn't say anything about the legacy descriptor
layout for the respone. So this patch tries to not assume the response
to reside in a single separate descriptor which is what commit
79c14141a487 ("vhost/scsi: Convert completion path to use") tries to
achieve towards to ANY_LAYOUT.
This is done by allocating and using dedicate resp iov in the
command. To be safety, start with UIO_MAXIOV to be consistent with the
limitation that we advertise to the vhost_get_vq_desc().
Testing with the hacked virtio-scsi driver that use 1 descriptor for 1
byte in the response.
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Benjamin Coddington <bcodding@redhat.com>
Cc: Nicholas Bellinger <nab@linux-iscsi.org>
Fixes: a77ec83a5789 ("vhost/scsi: fix reuse of &vq->iov[out] in response")
Signed-off-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20230119073647.76467-1-jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
|
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READ/WRITE proved to be actively confusing - the meanings are
"data destination, as used with read(2)" and "data source, as
used with write(2)", but people keep interpreting those as
"we read data from it" and "we write data to it", i.e. exactly
the wrong way.
Call them ITER_DEST and ITER_SOURCE - at least that is harder
to misinterpret...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
|
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Pull virtio updates from Michael Tsirkin:
- A huge patchset supporting vq resize using the new vq reset
capability
- Features, fixes, and cleanups all over the place
* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost: (88 commits)
vdpa/mlx5: Fix possible uninitialized return value
vdpa_sim_blk: add support for discard and write-zeroes
vdpa_sim_blk: add support for VIRTIO_BLK_T_FLUSH
vdpa_sim_blk: make vdpasim_blk_check_range usable by other requests
vdpa_sim_blk: check if sector is 0 for commands other than read or write
vdpa_sim: Implement suspend vdpa op
vhost-vdpa: uAPI to suspend the device
vhost-vdpa: introduce SUSPEND backend feature bit
vdpa: Add suspend operation
virtio-blk: Avoid use-after-free on suspend/resume
virtio_vdpa: support the arg sizes of find_vqs()
vhost-vdpa: Call ida_simple_remove() when failed
vDPA: fix 'cast to restricted le16' warnings in vdpa.c
vDPA: !FEATURES_OK should not block querying device config space
vDPA/ifcvf: support userspace to query features and MQ of a management device
vDPA/ifcvf: get_config_size should return a value no greater than dev implementation
vhost scsi: Allow user to control num virtqueues
vhost-scsi: Fix max number of virtqueues
vdpa/mlx5: Support different address spaces for control and data
vdpa/mlx5: Implement susupend virtqueue callback
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We are currently hard coded to always create 128 IO virtqueues, so this
adds a modparam to control it. For large systems where we are ok with
using memory for virtqueues it allows us to add up to 1024. This limit
was just selected becuase that's qemu's limit.
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Message-Id: <20220708030525.5065-3-michael.christie@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
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