scsi-disk: Always report RESERVATION_CONFLICT to guest

In the case of scsi-block, RESERVATION_CONFLICT is not a backend error,
but indicates that the guest tried to make a request that it isn't
allo

scsi-disk: Always report RESERVATION_CONFLICT to guest

In the case of scsi-block, RESERVATION_CONFLICT is not a backend error,
but indicates that the guest tried to make a request that it isn't
allowed to execute. Pass the error to the guest so that it can decide
what to do with it.

Without this, if we stop the VM in response to a RESERVATION_CONFLICT
(as is the default policy in management software such as oVirt or
KubeVirt), it can happen that the VM cannot be resumed any more because
every attempt to resume it immediately runs into the same error and
stops the VM again.

One case that expects RESERVATION_CONFLICT errors to be visible in the
guest is running the validation tests in Windows 2019's Failover Cluster
Manager, which intentionally tries to execute invalid requests to see if
they are properly rejected.

Buglink: https://issues.redhat.com/browse/RHEL-50000
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20240731123207.27636-5-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

show more ...

scsi-disk: Add warning comments that host_status errors take a shortcut

scsi_block_sgio_complete() has surprising behaviour in that there are
error cases in which it directly completes the request a

scsi-disk: Add warning comments that host_status errors take a shortcut

scsi_block_sgio_complete() has surprising behaviour in that there are
error cases in which it directly completes the request and never calls
the passed callback. In the current state of the code, this doesn't seem
to result in bugs, but with future code changes, we must be careful to
never rely on the callback doing some cleanup until this code smell is
fixed. For now, just add warnings to make people aware of the trap.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20240731123207.27636-4-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

show more ...

scsi-block: Don't skip callback for sgio error status/driver_status

Instead of calling into scsi_handle_rw_error() directly from
scsi_block_sgio_complete() and skipping the normal callback, go throu

scsi-block: Don't skip callback for sgio error status/driver_status

Instead of calling into scsi_handle_rw_error() directly from
scsi_block_sgio_complete() and skipping the normal callback, go through
the normal cleanup path by calling the callback with a positive error
value.

The important difference here is not only that the code path is cleaner,
but that the callbacks set r->req.aiocb = NULL. If we skip setting this
and the error action is BLOCK_ERROR_ACTION_STOP, resuming the VM runs
into an assertion failure in scsi_read_data() or scsi_write_data()
because the dangling aiocb pointer is unexpected.

Fixes: a108557bbf ("scsi: inline sg_io_sense_from_errno() into the callers.")
Buglink: https://issues.redhat.com/browse/RHEL-50000
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20240731123207.27636-3-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

show more ...

scsi-disk: Use positive return value for status in dma_readv/writev

In some error cases, scsi_block_sgio_complete() never calls the passed
callback, but directly completes the request. This leads to

scsi-disk: Use positive return value for status in dma_readv/writev

In some error cases, scsi_block_sgio_complete() never calls the passed
callback, but directly completes the request. This leads to bugs because
its error paths are not exact copies of what the callback would normally
do.

In preparation to fix this, allow passing positive return values to the
callbacks that represent the status code that should be used to complete
the request.

scsi_handle_rw_error() already handles positive values for its ret
parameter because scsi_block_sgio_complete() calls directly into it.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20240731123207.27636-2-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

show more ...

scsi-disk: Fix crash for VM configured with USB CDROM after live migration

For VMs configured with the USB CDROM device:

-drive file=/path/to/local/file,id=drive-usb-disk0,media=cdrom,readonly=on..

scsi-disk: Fix crash for VM configured with USB CDROM after live migration

For VMs configured with the USB CDROM device:

-drive file=/path/to/local/file,id=drive-usb-disk0,media=cdrom,readonly=on...
-device usb-storage,drive=drive-usb-disk0,id=usb-disk0...

QEMU process may crash after live migration, to reproduce the issue,
configure VM (Guest OS ubuntu 20.04 or 21.10) with the following XML:

<disk type='file' device='cdrom'>
<driver name='qemu' type='raw'/>
<source file='/path/to/share_fs/cdrom.iso'/>
<target dev='sda' bus='usb'/>
<readonly/>
<address type='usb' bus='0' port='2'/>
</disk>
<controller type='usb' index='0' model='piix3-uhci'/>

Do the live migration repeatedly, crash may happen after live migratoin,
trace log at the source before live migration is as follows:

324808@1711972823.521945:usb_uhci_frame_start nr 319
324808@1711972823.521978:usb_uhci_qh_load qh 0x35cb5400
324808@1711972823.521989:usb_uhci_qh_load qh 0x35cb5480
324808@1711972823.521997:usb_uhci_td_load qh 0x35cb5480, td 0x35cbe000, ctrl 0x0, token 0xffe07f69
324808@1711972823.522010:usb_uhci_td_nextqh qh 0x35cb5480, td 0x35cbe000
324808@1711972823.522022:usb_uhci_qh_load qh 0x35cb5680
324808@1711972823.522030:usb_uhci_td_load qh 0x35cb5680, td 0x75ac5180, ctrl 0x19800000, token 0x3c903e1
324808@1711972823.522045:usb_uhci_packet_add token 0x103e1, td 0x75ac5180
324808@1711972823.522056:usb_packet_state_change bus 0, port 2, ep 2, packet 0x559f9ba14b00, state undef -> setup
324808@1711972823.522079:usb_msd_cmd_submit lun 0, tag 0x472, flags 0x00000080, len 10, data-len 8
324808@1711972823.522107:scsi_req_parsed target 0 lun 0 tag 1138 command 74 dir 1 length 8
324808@1711972823.522124:scsi_req_parsed_lba target 0 lun 0 tag 1138 command 74 lba 4096
324808@1711972823.522139:scsi_req_alloc target 0 lun 0 tag 1138
324808@1711972823.522169:scsi_req_continue target 0 lun 0 tag 1138
324808@1711972823.522181:scsi_req_data target 0 lun 0 tag 1138 len 8
324808@1711972823.522194:usb_packet_state_change bus 0, port 2, ep 2, packet 0x559f9ba14b00, state setup -> complete
324808@1711972823.522209:usb_uhci_packet_complete_success token 0x103e1, td 0x75ac5180
324808@1711972823.522219:usb_uhci_packet_del token 0x103e1, td 0x75ac5180
324808@1711972823.522232:usb_uhci_td_complete qh 0x35cb5680, td 0x75ac5180

trace log at the destination after live migration is as follows:

3286206@1711972823.951646:usb_uhci_frame_start nr 320
3286206@1711972823.951663:usb_uhci_qh_load qh 0x35cb5100
3286206@1711972823.951671:usb_uhci_qh_load qh 0x35cb5480
3286206@1711972823.951680:usb_uhci_td_load qh 0x35cb5480, td 0x35cbe000, ctrl 0x1000000, token 0xffe07f69
3286206@1711972823.951693:usb_uhci_td_nextqh qh 0x35cb5480, td 0x35cbe000
3286206@1711972823.951702:usb_uhci_qh_load qh 0x35cb5700
3286206@1711972823.951709:usb_uhci_td_load qh 0x35cb5700, td 0x75ac5240, ctrl 0x39800000, token 0xe08369
3286206@1711972823.951727:usb_uhci_queue_add token 0x8369
3286206@1711972823.951735:usb_uhci_packet_add token 0x8369, td 0x75ac5240
3286206@1711972823.951746:usb_packet_state_change bus 0, port 2, ep 1, packet 0x56066b2fb5a0, state undef -> setup
3286206@1711972823.951766:usb_msd_data_in 8/8 (scsi 8)
2024-04-01 12:00:24.665+0000: shutting down, reason=crashed

The backtrace reveals the following:

Program terminated with signal SIGSEGV, Segmentation fault.
0 __memmove_sse2_unaligned_erms () at ../sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S:312
312 movq -8(%rsi,%rdx), %rcx
[Current thread is 1 (Thread 0x7f0a9025fc00 (LWP 3286206))]
(gdb) bt
0 __memmove_sse2_unaligned_erms () at ../sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S:312
1 memcpy (__len=8, __src=<optimized out>, __dest=<optimized out>) at /usr/include/bits/string_fortified.h:34
2 iov_from_buf_full (iov=<optimized out>, iov_cnt=<optimized out>, offset=<optimized out>, buf=0x0, bytes=bytes@entry=8) at ../util/iov.c:33
3 iov_from_buf (bytes=8, buf=<optimized out>, offset=<optimized out>, iov_cnt=<optimized out>, iov=<optimized out>)
at /usr/src/debug/qemu-6-6.2.0-75.7.oe1.smartx.git.40.x86_64/include/qemu/iov.h:49
4 usb_packet_copy (p=p@entry=0x56066b2fb5a0, ptr=<optimized out>, bytes=bytes@entry=8) at ../hw/usb/core.c:636
5 usb_msd_copy_data (s=s@entry=0x56066c62c770, p=p@entry=0x56066b2fb5a0) at ../hw/usb/dev-storage.c:186
6 usb_msd_handle_data (dev=0x56066c62c770, p=0x56066b2fb5a0) at ../hw/usb/dev-storage.c:496
7 usb_handle_packet (dev=0x56066c62c770, p=p@entry=0x56066b2fb5a0) at ../hw/usb/core.c:455
8 uhci_handle_td (s=s@entry=0x56066bd5f210, q=0x56066bb7fbd0, q@entry=0x0, qh_addr=qh_addr@entry=902518530, td=td@entry=0x7fffe6e788f0, td_addr=<optimized out>,
int_mask=int_mask@entry=0x7fffe6e788e4) at ../hw/usb/hcd-uhci.c:885
9 uhci_process_frame (s=s@entry=0x56066bd5f210) at ../hw/usb/hcd-uhci.c:1061
10 uhci_frame_timer (opaque=opaque@entry=0x56066bd5f210) at ../hw/usb/hcd-uhci.c:1159
11 timerlist_run_timers (timer_list=0x56066af26bd0) at ../util/qemu-timer.c:642
12 qemu_clock_run_timers (type=QEMU_CLOCK_VIRTUAL) at ../util/qemu-timer.c:656
13 qemu_clock_run_all_timers () at ../util/qemu-timer.c:738
14 main_loop_wait (nonblocking=nonblocking@entry=0) at ../util/main-loop.c:542
15 qemu_main_loop () at ../softmmu/runstate.c:739
16 main (argc=<optimized out>, argv=<optimized out>, envp=<optimized out>) at ../softmmu/main.c:52
(gdb) frame 5
(gdb) p ((SCSIDiskReq *)s->req)->iov
$1 = {iov_base = 0x0, iov_len = 0}
(gdb) p/x s->req->tag
$2 = 0x472

When designing the USB mass storage device model, QEMU places SCSI disk
device as the backend of USB mass storage device. In addition, USB mass
device driver in Guest OS conforms to the "Universal Serial Bus Mass
Storage Class Bulk-Only Transport" specification in order to simulate
the transform behavior between a USB controller and a USB mass device.
The following shows the protocol hierarchy:

+----------------+
CDROM driver | scsi command | CDROM
+----------------+

+-----------------------+
USB mass | USB Mass Storage Class| USB mass
storage driver | Bulk-Only Transport | storage device
+-----------------------+

+----------------+
USB Controller | USB Protocol | USB device
+----------------+

In the USB protocol layer, between the USB controller and USB device, at
least two USB packets will be transformed when guest OS send a
read operation to USB mass storage device:

1. The CBW packet, which will be delivered to the USB device's Bulk-Out
endpoint. In order to simulate a read operation, the USB mass storage
device parses the CBW and converts it to a SCSI command, which would be
executed by CDROM(represented as SCSI disk in QEMU internally), and store
the result data of the SCSI command in a buffer.

2. The DATA-IN packet, which will be delivered from the USB device's
Bulk-In endpoint(fetched directly from the preceding buffer) to the USB
controller.

We consider UHCI to be the controller. The two packets mentioned above may
have been processed by UHCI in two separate frame entries of the Frame List
, and also described by two different TDs. Unlike the physical environment,
a virtualized environment requires the QEMU to make sure that the result
data of CBW is not lost and is delivered to the UHCI controller.

Currently, these types of SCSI requests are not migrated, so QEMU cannot
ensure the result data of the IO operation is not lost if there are
inflight emulated SCSI requests during the live migration.

Assume for the moment that the USB mass storage device is processing the
CBW and storing the result data of the read operation to a buffre, live
migration happens and moves the VM to the destination while not migrating
the result data of the read operation.

After migration, when UHCI at the destination issues a DATA-IN request to
the USB mass storage device, a crash happens because USB mass storage device
fetches the result data and get nothing.

The scenario this patch addresses is this one.

Theoretically, any device that uses the SCSI disk as a back-end would be
affected by this issue. In this case, it is the USB CDROM.

To fix it, inflight emulated SCSI request be migrated during live migration,
similar to the DMA SCSI request.

Signed-off-by: Hyman Huang <yong.huang@smartx.com>
Message-ID: <878c8f093f3fc2f584b5c31cb2490d9f6a12131a.1716531409.git.yong.huang@smartx.com>
[Do not bump migration version, introduce compat property instead. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

show more ...

scsi-disk: Don't silently truncate serial number

Before this commit, scsi-disk accepts a string of arbitrary length for
its "serial" property. However, the value visible on the guest is
actually tru

scsi-disk: Don't silently truncate serial number

Before this commit, scsi-disk accepts a string of arbitrary length for
its "serial" property. However, the value visible on the guest is
actually truncated to 36 characters. This limitation doesn't come from
the SCSI specification, it is an arbitrary limit that was initially
picked as 20 and later bumped to 36 by commit 48b62063.

Similarly, device_id was introduced as a copy of the serial number,
limited to 20 characters, but commit 48b62063 forgot to actually bump
it.

As long as we silently truncate the given string, extending the limit is
actually not a harmless change, but break the guest ABI. This is the
most important reason why commit 48b62063 was really wrong (and it's
also why we can't change device_id to be in sync with the serial number
again and use 36 characters now, it would be another guest ABI
breakage).

In order to avoid future breakage, don't silently truncate the serial
number string any more, but just error out if it would be truncated.

Buglink: https://issues.redhat.com/browse/RHEL-3542
Suggested-by: Peter Krempa <pkrempa@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20240604161755.63448-1-kwolf@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

show more ...

hw/scsi/scsi-disk: Use qemu_hexdump_line to avoid sprintf

sprintf() is deprecated on Darwin since macOS 13.0 / XCode 14.1.
Using qemu_hexdump_line both fixes the deprecation warning and
simplifies t

hw/scsi/scsi-disk: Use qemu_hexdump_line to avoid sprintf

sprintf() is deprecated on Darwin since macOS 13.0 / XCode 14.1.
Using qemu_hexdump_line both fixes the deprecation warning and
simplifies the code base.

Note that this drops the "0x" prefix to every byte, which should
be of no consequence to tracing.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20240412073346.458116-9-richard.henderson@linaro.org>

show more ...

hw/scsi: Constify VMState

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20231221031652.119827-52-richard.henderson@linaro.org>

scsi: remove outdated AioContext lock comment

The SCSI subsystem no longer uses the AioContext lock. Request
processing runs exclusively in the BlockBackend's AioContext since
"scsi: only access SCS

scsi: remove outdated AioContext lock comment

The SCSI subsystem no longer uses the AioContext lock. Request
processing runs exclusively in the BlockBackend's AioContext since
"scsi: only access SCSIDevice->requests from one thread" and hence the
lock is unnecessary.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-ID: <20231205182011.1976568-13-stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

show more ...

scsi: remove AioContext locking

The AioContext lock no longer has any effect. Remove it.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-ID:

scsi: remove AioContext locking

The AioContext lock no longer has any effect. Remove it.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-ID: <20231205182011.1976568-9-stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

show more ...

scsi: assert that callbacks run in the correct AioContext

Since the removal of AioContext locking, the correctness of the code
relies on running requests from a single AioContext at any given time.

scsi: assert that callbacks run in the correct AioContext

Since the removal of AioContext locking, the correctness of the code
relies on running requests from a single AioContext at any given time.

Add assertions that verify that callbacks are invoked in the correct
AioContext.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20231205182011.1976568-3-stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

show more ...

scsi: don't lock AioContext in I/O code path

blk_aio_*() doesn't require the AioContext lock and the SCSI subsystem's
internal state also does not anymore.

Signed-off-by: Stefan Hajnoczi <stefanha@

scsi: don't lock AioContext in I/O code path

blk_aio_*() doesn't require the AioContext lock and the SCSI subsystem's
internal state also does not anymore.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Acked-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20231204164259.1515217-4-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

show more ...

scsi-disk: ensure that FORMAT UNIT commands are terminated

Otherwise when a FORMAT UNIT command is issued, the SCSI layer can become
confused because it can find itself in the situation where it thi

scsi-disk: ensure that FORMAT UNIT commands are terminated

Otherwise when a FORMAT UNIT command is issued, the SCSI layer can become
confused because it can find itself in the situation where it thinks there
is still data to be transferred which can cause the next emulated SCSI
command to fail.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Fixes: 6ab71761 ("scsi-disk: add FORMAT UNIT command")
Tested-by: Thomas Huth <thuth@redhat.com>
Message-ID: <20230913204410.65650-4-mark.cave-ayland@ilande.co.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

show more ...

hw/scsi/scsi-disk: Disallow block sizes smaller than 512 [CVE-2023-42467]

We are doing things like

nb_sectors /= (s->qdev.blocksize / BDRV_SECTOR_SIZE);

in the code here (e.g. in scsi_disk_emu

hw/scsi/scsi-disk: Disallow block sizes smaller than 512 [CVE-2023-42467]

We are doing things like

nb_sectors /= (s->qdev.blocksize / BDRV_SECTOR_SIZE);

in the code here (e.g. in scsi_disk_emulate_mode_sense()), so if
the blocksize is smaller than BDRV_SECTOR_SIZE (=512), this crashes
with a division by 0 exception. Thus disallow block sizes of 256
bytes to avoid this situation.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1813
CVE: 2023-42467
Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-ID: <20230925091854.49198-1-thuth@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

show more ...

virtio-scsi: implement BlockDevOps->drained_begin()

The virtio-scsi Host Bus Adapter provides access to devices on a SCSI
bus. Those SCSI devices typically have a BlockBackend. When the
BlockBackend

virtio-scsi: implement BlockDevOps->drained_begin()

The virtio-scsi Host Bus Adapter provides access to devices on a SCSI
bus. Those SCSI devices typically have a BlockBackend. When the
BlockBackend enters a drained section, the SCSI device must temporarily
stop submitting new I/O requests.

Implement this behavior by temporarily stopping virtio-scsi virtqueue
processing when one of the SCSI devices enters a drained section. The
new scsi_device_drained_begin() API allows scsi-disk to message the
virtio-scsi HBA.

scsi_device_drained_begin() uses a drain counter so that multiple SCSI
devices can have overlapping drained sections. The HBA only sees one
pair of .drained_begin/end() calls.

After this commit, virtio-scsi no longer depends on hw/virtio's
ioeventfd aio_set_event_notifier(is_external=true). This commit is a
step towards removing the aio_disable_external() API.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20230516190238.8401-19-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

show more ...

dma-helpers: prevent dma_blk_cb() vs dma_aio_cancel() race

dma_blk_cb() only takes the AioContext lock around ->io_func(). That
means the rest of dma_blk_cb() is not protected. In particular, the
DM

dma-helpers: prevent dma_blk_cb() vs dma_aio_cancel() race

dma_blk_cb() only takes the AioContext lock around ->io_func(). That
means the rest of dma_blk_cb() is not protected. In particular, the
DMAAIOCB field accesses happen outside the lock.

There is a race when the main loop thread holds the AioContext lock and
invokes scsi_device_purge_requests() -> bdrv_aio_cancel() ->
dma_aio_cancel() while an IOThread executes dma_blk_cb(). The dbs->acb
field determines how cancellation proceeds. If dma_aio_cancel() sees
dbs->acb == NULL while dma_blk_cb() is still running, the request can be
completed twice (-ECANCELED and the actual return value).

The following assertion can occur with virtio-scsi when an IOThread is
used:

../hw/scsi/scsi-disk.c:368: scsi_dma_complete: Assertion `r->req.aiocb != NULL' failed.

Fix the race by holding the AioContext across dma_blk_cb(). Now
dma_aio_cancel() under the AioContext lock will not see
inconsistent/intermediate states.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20230221212218.1378734-3-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

show more ...

scsi: protect req->aiocb with AioContext lock

If requests are being processed in the IOThread when a SCSIDevice is
unplugged, scsi_device_purge_requests() -> scsi_req_cancel_async() races
with I/O c

scsi: protect req->aiocb with AioContext lock

If requests are being processed in the IOThread when a SCSIDevice is
unplugged, scsi_device_purge_requests() -> scsi_req_cancel_async() races
with I/O completion callbacks. Both threads load and store req->aiocb.
This can lead to assert(r->req.aiocb == NULL) failures and undefined
behavior.

Protect r->req.aiocb with the AioContext lock to prevent the race.

Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20230221212218.1378734-2-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

show more ...

block: Convert bdrv_refresh_total_sectors() to co_wrapper_mixed

BlockDriver->bdrv_getlength is categorized as IO callback, and it
currently doesn't run in a coroutine. We should let it take a graph

block: Convert bdrv_refresh_total_sectors() to co_wrapper_mixed

BlockDriver->bdrv_getlength is categorized as IO callback, and it
currently doesn't run in a coroutine. We should let it take a graph
rdlock since the callback traverses the block nodes graph, which however
is only possible in a coroutine.

Therefore turn it into a co_wrapper to move the actual function into a
coroutine where the lock can be taken.

Because now this function creates a new coroutine and polls, we need to
take the AioContext lock where it is missing, for the only reason that
internally co_wrapper calls AIO_WAIT_WHILE and it expects to release the
AioContext lock.

This is especially messy when a co_wrapper creates a coroutine and polls
in bdrv_open_driver, because this function has so many callers in so
many context that it can easily lead to deadlocks. Therefore the new
rule for bdrv_open_driver is that the caller must always hold the
AioContext lock of the given bs (except if it is a coroutine), because
the function calls bdrv_refresh_total_sectors() which is now a
co_wrapper.

Once the rwlock is ultimated and placed in every place it needs to be,
we will poll using AIO_WAIT_WHILE_UNLOCKED and remove the AioContext
lock.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20230113204212.359076-7-kwolf@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

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scsi-disk: support setting CD-ROM block size via device options

SunOS expects CD-ROM devices to have a block size of 512, and will
fail to mount or install using QEMU's default block size of 2048.

scsi-disk: support setting CD-ROM block size via device options

SunOS expects CD-ROM devices to have a block size of 512, and will
fail to mount or install using QEMU's default block size of 2048.

When initializing the SCSI device, allow the `physical_block_size'
block device option to override the default block size.

Signed-off-by: John Millikin <john@john-millikin.com>
Message-Id: <20220804122950.1577012-1-john@john-millikin.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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scsi: Add buf_len parameter to scsi_req_new()

When a SCSI command is received from the guest, the CDB length implied
by the first byte might exceed the number of bytes the guest sent. In
this case s

scsi: Add buf_len parameter to scsi_req_new()

When a SCSI command is received from the guest, the CDB length implied
by the first byte might exceed the number of bytes the guest sent. In
this case scsi_req_new() will read uninitialized data, causing
unpredictable behavior.

Adds the buf_len parameter to scsi_req_new() and plumbs it through the
call stack.

Signed-off-by: John Millikin <john@john-millikin.com>
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1127
Message-Id: <20220817053458.698416-1-john@john-millikin.com>
[Fill in correct length for adapters other than ESP. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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scsi-disk: ensure block size is non-zero and changes limited to bits 8-15

The existing code assumes that the block size can be generated from p[1] << 8
in multiple places which ignores the top and b

scsi-disk: ensure block size is non-zero and changes limited to bits 8-15

The existing code assumes that the block size can be generated from p[1] << 8
in multiple places which ignores the top and bottom 8 bits. If the block size
is allowed to be set to an arbitrary value then this causes a mismatch
between the value written by the guest in the block descriptor and the value
subsequently read back using READ CAPACITY causing the guest to generate
requests that can crash QEMU.

For now restrict block size changes to bits 8-15 and also ignore requests to
set the block size to 0 which causes the SCSI emulation to crash in at least
one place with a divide by zero error.

Fixes: 356c4c441e ("scsi-disk: allow MODE SELECT block descriptor to set the block size")
Closes: https://gitlab.com/qemu-project/qemu/-/issues/1112
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Message-Id: <20220730122656.253448-3-mark.cave-ayland@ilande.co.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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scsi-disk: fix overflow when block size is not a multiple of BDRV_SECTOR_SIZE

In scsi_disk_emulate_write_same() the number of host sectors to transfer is
calculated as (s->qdev.blocksize / BDRV_SECT

scsi-disk: fix overflow when block size is not a multiple of BDRV_SECTOR_SIZE

In scsi_disk_emulate_write_same() the number of host sectors to transfer is
calculated as (s->qdev.blocksize / BDRV_SECTOR_SIZE) which is then used to
copy data in block size chunks to the iov buffer.

Since the loop copying the data to the iov buffer uses a fixed increment of
s->qdev.blocksize then using a block size that isn't a multiple of
BDRV_SECTOR_SIZE introduces a rounding error in the iov buffer size calculation
such that the iov buffer copy overflows the space allocated.

Update the iov buffer copy for() loop so that it will use the smallest of either
the current block size or the remaining transfer count to prevent the overflow.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Message-Id: <20220730122656.253448-2-mark.cave-ayland@ilande.co.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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scsi-disk: allow MODE SELECT block descriptor to set the block size

The MODE SELECT command can contain an optional block descriptor that can be used
to set the device block size. If the block descr

scsi-disk: allow MODE SELECT block descriptor to set the block size

The MODE SELECT command can contain an optional block descriptor that can be used
to set the device block size. If the block descriptor is present then update the
block size on the SCSI device accordingly.

This allows CDROMs to be used with A/UX which requires a CDROM drive which is
capable of switching from a 2048 byte sector size to a 512 byte sector size.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Message-Id: <20220622105314.802852-13-mark.cave-ayland@ilande.co.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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scsi-disk: allow the MODE_PAGE_R_W_ERROR AWRE bit to be changeable for CDROM drives

A/UX sends a MODE_PAGE_R_W_ERROR command with the AWRE bit set to 0 when enumerating
CDROM drives. Since the bit i

scsi-disk: allow the MODE_PAGE_R_W_ERROR AWRE bit to be changeable for CDROM drives

A/UX sends a MODE_PAGE_R_W_ERROR command with the AWRE bit set to 0 when enumerating
CDROM drives. Since the bit is currently hardcoded to 1 then indicate that the AWRE
bit can be changed (even though we don't care about the value) so that
the MODE_PAGE_R_W_ERROR page can be set successfully.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Message-Id: <20220622105314.802852-12-mark.cave-ayland@ilande.co.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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scsi-disk: add SCSI_DISK_QUIRK_MODE_PAGE_TRUNCATED quirk for Macintosh

When A/UX configures the CDROM device it sends a truncated MODE SELECT request
for page 1 (MODE_PAGE_R_W_ERROR) which is only 6

scsi-disk: add SCSI_DISK_QUIRK_MODE_PAGE_TRUNCATED quirk for Macintosh

When A/UX configures the CDROM device it sends a truncated MODE SELECT request
for page 1 (MODE_PAGE_R_W_ERROR) which is only 6 bytes in length rather than
10. This seems to be due to bug in Apple's code which calculates the CDB message
length incorrectly.

The work at [1] suggests that this truncated request is accepted on real
hardware whereas in QEMU it generates an INVALID_PARAM_LEN sense code which
causes A/UX to get stuck in a loop retrying the command in an attempt to succeed.

Alter the mode page request length check so that truncated requests are allowed
if the SCSI_DISK_QUIRK_MODE_PAGE_TRUNCATED quirk is enabled, whilst also adding a
trace event to enable the condition to be detected.

[1] https://68kmla.org/bb/index.php?threads/scsi2sd-project-anyone-interested.29040/page-7#post-316444

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Message-Id: <20220622105314.802852-10-mark.cave-ayland@ilande.co.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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