AVX512VL has VPROLD and VPROLQ, layered onto the same
opcode as PSHIFTD, but requires EVEX encoding and W1.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
valgrind pointed out that arg_info()->val can be undefined which will
be the case if the arguments are not constant. The ordering of the
checks will have ensured we never relied on an undefined value but for
the sake of completeness re-order the code to be clear.
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20220209112142.3367525-1-alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
.bdrv_amend_clean() says block drivers can use it to clean up what was
done in .bdrv_amend_pre_run(). Therefore, it should always be called
after .bdrv_amend_pre_run(), which means we need it to call it in the
JobDriver.free() callback, not in JobDriver.clean().
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20220304153729.711387-3-hreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Instead of failing the iotests if GNU sed is not available (or skipping
them completely in the check-block.sh script), it would be better to
simply skip the bash-based tests that rely on GNU sed, so that the other
tests could still be run. Thus we now explicitely use "gsed" (either as
direct program or as a wrapper around "sed" if it's the GNU version)
in the spots that rely on the GNU sed behavior. Statements that use the
"-r" parameter of sed have been switched to use "-E" instead, since this
switch is supported by all sed versions on our supported build hosts
(most also support "-r", but macOS' sed only supports "-E"). With all
these changes in place, we then can also remove the sed checks from the
check-block.sh script, so that "make check-block" can now be run on
systems without GNU sed, too.
Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20220216125454.465041-1-thuth@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Test the following scenario:
1. Some block node (null-co) attached to a user (here: NBD server) that
performs I/O and keeps the node in an I/O thread
2. Repeatedly run blockdev-add/blockdev-del to add/remove an overlay
to/from that node
Each blockdev-add triggers bdrv_refresh_limits(), and because
blockdev-add runs in the main thread, it does not stop the I/O requests.
I/O can thus happen while the limits are refreshed, and when such a
request sees a temporarily invalid block limit (e.g. alignment is 0),
this may easily crash qemu (or the storage daemon in this case).
The block layer needs to ensure that I/O requests to a node are paused
while that node's BlockLimits are refreshed.
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20220216105355.30729-4-hreitz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
bdrv_refresh_limits() recurses down to the node's children. That does
not seem necessary: When we refresh limits on some node, and then
recurse down and were to change one of its children's BlockLimits, then
that would mean we noticed the changed limits by pure chance. The fact
that we refresh the parent's limits has nothing to do with it, so the
reason for the change probably happened before this point in time, and
we should have refreshed the limits then.
Consequently, we should actually propagate block limits changes upwards,
not downwards. That is a separate and pre-existing issue, though, and
so will not be addressed in this patch.
The problem with recursing is that bdrv_refresh_limits() is not atomic.
It begins with zeroing BDS.bl, and only then sets proper, valid limits.
If we do not drain all nodes whose limits are refreshed, then concurrent
I/O requests can encounter invalid request_alignment values and crash
qemu. Therefore, a recursing bdrv_refresh_limits() requires the whole
subtree to be drained, which is currently not ensured by most callers.
A non-recursive bdrv_refresh_limits() only requires the node in question
to not receive I/O requests, and this is done by most callers in some
way or another:
- bdrv_open_driver() deals with a new node with no parents yet
- bdrv_set_file_or_backing_noperm() acts on a drained node
- bdrv_reopen_commit() acts only on drained nodes
- bdrv_append() should in theory require the node to be drained; in
practice most callers just lock the AioContext, which should at least
be enough to prevent concurrent I/O requests from accessing invalid
limits
So we can resolve the bug by making bdrv_refresh_limits() non-recursive.
Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1879437
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20220216105355.30729-2-hreitz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
block coroutines functions run in different aiocontext, and are
not protected by the BQL. Therefore are I/O.
On the other side, generated_co_wrapper functions use BDRV_POLL_WHILE,
meaning the caller can either be the main loop or a specific iothread.
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <20220303151616.325444-25-eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Snapshots run also under the BQL, so they all are
in the global state API. The aiocontext lock that they hold
is currently an overkill and in future could be removed.
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <20220303151616.325444-23-eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
We want to be sure that the functions that write the child and
parent list of a bs are under BQL and drain.
BQL prevents from concurrent writings from the GS API, while
drains protect from I/O.
TODO: drains are missing in some functions using this assert.
Therefore a proper assertion will fail. Because adding drains
requires additional discussions, they will be added in future
series.
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <20220303151616.325444-15-eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Similarly to the previous patch, split block_int.h
in block_int-io.h and block_int-global-state.h
block_int-common.h contains the structures shared between
the two headers, and the functions that can't be categorized as
I/O or global state.
Assertions are added in the next patch.
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <20220303151616.325444-12-eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Now that we "covered" the three main cases where the
permission API was being used under BQL (fuse,
amend and invalidate_cache), we can safely assert for
the permission functions implemented in block.c
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <20220303151616.325444-11-eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
All the global state (GS) API functions will check that
qemu_in_main_thread() returns true. If not, it means
that the safety of BQL cannot be guaranteed, and
they need to be moved to I/O.
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <20220303151616.325444-9-eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Similarly to the previous patches, split block-backend.h
in block-backend-io.h and block-backend-global-state.h
In addition, remove "block/block.h" include as it seems
it is not necessary anymore, together with "qemu/iov.h"
block-backend-common.h contains the structures shared between
the two headers, and the functions that can't be categorized as
I/O or global state.
Assertions are added in the next patch.
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <20220303151616.325444-8-eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Allow writable exports to get BLK_PERM_RESIZE permission
from creation, in fuse_export_create().
In this way, there is no need to give the permission in
fuse_do_truncate(), which might be run in an iothread.
Permissions should be set only in the main thread, so
in any case if an iothread tries to set RESIZE, it will
be blocked.
Also assert in fuse_do_truncate that if we give the
RESIZE permission we can then restore the original ones.
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20220303151616.325444-7-eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
All the global state (GS) API functions will check that
qemu_in_main_thread() returns true. If not, it means
that the safety of BQL cannot be guaranteed, and
they need to be moved to I/O.
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <20220303151616.325444-5-eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
block.h currently contains a mix of functions:
some of them run under the BQL and modify the block layer graph,
others are instead thread-safe and perform I/O in iothreads.
Some others can only be called by either the main loop or the
iothread running the AioContext (and not other iothreads),
and using them in another thread would cause deadlocks, and therefore
it is not ideal to define them as I/O.
It is not easy to understand which function is part of which
group (I/O vs GS vs "I/O or GS"), and this patch aims to clarify it.
The "GS" functions need the BQL, and often use
aio_context_acquire/release and/or drain to be sure they
can modify the graph safely.
The I/O function are instead thread safe, and can run in
any AioContext.
"I/O or GS" functions run instead in the main loop or in
a single iothread, and use BDRV_POLL_WHILE().
By splitting the header in two files, block-io.h
and block-global-state.h we have a clearer view on what
needs what kind of protection. block-common.h
contains common structures shared by both headers.
block.h is left there for legacy and to avoid changing
all includes in all c files that use the block APIs.
Assertions are added in the next patch.
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <20220303151616.325444-4-eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Righ now, IO_CODE and IO_OR_GS_CODE are nop, as there isn't
really a way to check that a function is only called in I/O.
On the other side, we can use qemu_in_main_thread() to check if
we are in the main loop.
The usage of macros makes easy to extend them in the future without
making changes in all callers. They will also visually help understanding
in which category each function is, without looking at the header.
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <20220303151616.325444-3-eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
When invoked from the main loop, this function is the same
as qemu_mutex_iothread_locked, and returns true if the BQL is held.
When invoked from iothreads or tests, it returns true only
if the current AioContext is the Main Loop.
This essentially just extends qemu_mutex_iothread_locked to work
also in unit tests or other users like storage-daemon, that run
in the Main Loop but end up using the implementation in
stubs/iothread-lock.c.
Using qemu_mutex_iothread_locked in unit tests defaults to false
because they use the implementation in stubs/iothread-lock,
making all assertions added in next patches fail despite the
AioContext is still the main loop.
See the comment in the function header for more information.
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <20220303151616.325444-2-eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
