In preparation of making it a qdev property.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <1458066895-20632-36-git-send-email-armbru@redhat.com>
ivshmem_realize() puts the shared memory region in a container region.
Used to be necessary to permit delayed mapping of the shared memory.
However, we recently moved to synchronous mapping, in "ivshmem:
Receive shared memory synchronously in realize()" and the commit
following it. The container is redundant since then. Drop it.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <1458066895-20632-33-git-send-email-armbru@redhat.com>
ivshmem has its very own code to create and map shared memory.
Replace that with an implicitly created memory backend. Reduces the
number of ways we create BAR 2 from three to two.
The memory-backend-file is currently available only with CONFIG_LINUX,
so this adds a second Linuxism to ivshmem (the other one is eventfd).
Should we ever need to make it portable to systems where
memory-backend-file can't be made to serve, we could create a
memory-backend-shmem that allocates memory with shm_open().
Bonus fix: shared memory files are now created with permissions 0655
instead of 0777.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <1458066895-20632-32-git-send-email-armbru@redhat.com>
If size_t is narrower than 64 bits, passing uint64_t ivshmem_size to
mmap() truncates. Reject such sizes.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <1458066895-20632-31-git-send-email-armbru@redhat.com>
Short reads from a UNIX domain sockets are exceedingly unlikely when
the other side always sends eight bytes and we always read eight
bytes. We cope with them anyway. However, the code doing that is
rather convoluted. Dumb it down radically.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <1458066895-20632-30-git-send-email-armbru@redhat.com>
The chardev must be capable of transmitting SCM_RIGHTS ancillary
messages. We check it by comparing CharDriverState member filename to
"unix:". That's almost as brittle as it is disgusting.
When the actual transmission all happened asynchronously, this check
was all we could do in realize(), and thus better than nothing. But
now we receive at least one SCM_RIGHTS synchronously in realize(),
it's not worth its keep anymore. Drop it.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <1458066895-20632-29-git-send-email-armbru@redhat.com>
The protocol specification (ivshmem-spec.txt, formerly
ivshmem_device_spec.txt) has always required the ID message to be sent
right at the beginning, and ivshmem-server has always complied. The
device, however, accepts it out of order. If an interrupt setup
arrived before it, though, it would be misinterpreted as connect
notification. Fix the latent bug by relying on the spec and
ivshmem-server's actual behavior.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <1458066895-20632-28-git-send-email-armbru@redhat.com>
This kills off the funny state described in the previous commit.
Simplify ivshmem_io_read() accordingly, and update documentation.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <1458066895-20632-27-git-send-email-armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
When configured for interrupts (property "chardev" given), we receive
the shared memory from an ivshmem server. We do so asynchronously
after realize() completes, by setting up callbacks with
qemu_chr_add_handlers().
Keeping server I/O out of realize() that way avoids delays due to a
slow server. This is probably relevant only for hot plug.
However, this funny "no shared memory, yet" state of the device also
causes a raft of issues that are hard or impossible to work around:
* The guest is exposed to this state: when we enter and leave it its
shared memory contents is apruptly replaced, and device register
IVPosition changes.
This is a known issue. We document that guests should not access
the shared memory after device initialization until the IVPosition
register becomes non-negative.
For cold plug, the funny state is unlikely to be visible in
practice, because we normally receive the shared memory long before
the guest gets around to mess with the device.
For hot plug, the timing is tighter, but the relative slowness of
PCI device configuration has a good chance to hide the funny state.
In either case, guests complying with the documented procedure are
safe.
* Migration becomes racy.
If migration completes before the shared memory setup completes on
the source, shared memory contents is silently lost. Fortunately,
migration is rather unlikely to win this race.
If the shared memory's ramblock arrives at the destination before
shared memory setup completes, migration fails.
There is no known way for a management application to wait for
shared memory setup to complete.
All you can do is retry failed migration. You can improve your
chances by leaving more time between running the destination QEMU
and the migrate command.
To mitigate silent memory loss, you need to ensure the server
initializes shared memory exactly the same on source and
destination.
These issues are entirely undocumented so far.
I'd expect the server to be almost always fast enough to hide these
issues. But then rare catastrophic races are in a way the worst kind.
This is way more trouble than I'm willing to take from any device.
Kill the funny state by receiving shared memory synchronously in
realize(). If your hot plug hangs, go kill your ivshmem server.
For easier review, this commit only makes the receive synchronous, it
doesn't add the necessary error propagation. Without that, the funny
state persists. The next commit will do that, and kill it off for
real.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <1458066895-20632-26-git-send-email-armbru@redhat.com>
close_peer_eventfds() cleans up three things: ioeventfd triggers if
they exist, eventfds, and the array to store them.
Commit 98609cd (v1.2.0) fixed it not to clean up ioeventfd triggers
when they don't exist (property ioeventfd=off, which is the default).
Unfortunately, the fix also made it skip cleanup of the eventfds and
the array then. This is a memory and file descriptor leak on unplug.
Additionally, the reset of nb_eventfds is skipped. Doesn't matter on
unplug. On peer disconnect, however, this permanently wedges the
interrupt vectors used for that peer's ID. The eventfds stay behind,
but aren't connected to a peer anymore. When the ID gets recycled for
a new peer, the new peer's eventfds get assigned to vectors after the
old ones. Commonly, the device's number of vectors matches the
server's, so the new ones get dropped with a "Too many eventfd
received" message. Interrupts either don't work (common case) or go
to the wrong vector.
Fix by narrowing the conditional to just the ioeventfd trigger
cleanup.
While there, move the "invalid" peer check to the only caller where it
can actually happen, and tighten it to reject own ID.
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <1458066895-20632-25-git-send-email-armbru@redhat.com>
ivshmem_read() processes server messages. These are 64 bit signed
integers. -1 is shared memory setup, 16 bit unsigned is a peer ID,
anything else is invalid.
ivshmem_read() rejects invalid negative messages right away, silently.
Invalid positive messages get rejected only in resize_peers(), and
ivshmem_read() then prints the rather cryptic message "failed to
resize peers array".
Extend the first check to cover all invalid messages, make it report
"server sent invalid message", and drop the second check.
Now resize_peers() can't fail anymore; simplify.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <1458066895-20632-23-git-send-email-armbru@redhat.com>
An interrupt is set up when the interrupt's file descriptor is
received. Each message applies to the next interrupt vector.
Therefore, each vector cannot be set up more than once.
ivshmem_add_kvm_msi_virq() half-heartedly tries not to rely on this by
doing nothing then, but that's not going to recover from this error
should it become possible in the future. watch_vector_notifier()
doesn't even try.
Simply assert what is the case, so we get alerted if we ever screw it
up.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <1458066895-20632-22-git-send-email-armbru@redhat.com>
The ivshmem device can either use MSI-X or legacy INTx for interrupts.
With MSI-X enabled, peer interrupt events trigger an MSI as they
should. But software can still raise INTx via interrupt status and
mask register in BAR 0. This is explicitly prohibited by PCI Local
Bus Specification Revision 3.0, section 6.8.3.3:
While enabled for MSI or MSI-X operation, a function is prohibited
from using its INTx# pin (if implemented) to request service (MSI,
MSI-X, and INTx# are mutually exclusive).
Fix the device model to leave INTx alone when using MSI-X.
Document that we claim to use INTx in config space even when we don't.
Unlike other devices, ivshmem does *not* use INTx when configured for
MSI-X and MSI-X isn't enabled by software.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <1458066895-20632-21-git-send-email-armbru@redhat.com>
There are three predicates related to MSI-X:
* ivshmem_has_feature(s, IVSHMEM_MSI) is true unless the non-MSI-X
variant of the device is selected with msi=off.
* msix_present() is true when the device has the PCI capability MSI-X.
It's initially false, and becomes true during successful realize of
the MSI-X variant of the device. Thus, it's the same as
ivshmem_has_feature(s, IVSHMEM_MSI) for realized devices.
* msix_enabled() is true when msix_present() is true and guest software
has enabled MSI-X.
Code that differs between the non-MSI-X and the MSI-X variant of the
device needs to be guarded by ivshmem_has_feature(s, IVSHMEM_MSI) or
by msix_present(), except the latter works only for realized devices.
Code that depends on whether MSI-X is in use needs to be guarded with
msix_enabled().
Code review led me to two minor messes:
* ivshmem_vector_notify() calls msix_notify() even when
!msix_enabled(), unlike most other MSI-X-capable devices. As far as
I can tell, msix_notify() does nothing when !msix_enabled(). Add
the guard anyway.
* Most callers of ivshmem_use_msix() guard it with
ivshmem_has_feature(s, IVSHMEM_MSI). Not necessary, because
ivshmem_use_msix() does nothing when !msix_present(). That's
ivshmem's only use of msix_present(), though. Guard it
consistently, and drop the now redundant msix_present() check.
While there, rename ivshmem_use_msix() to ivshmem_msix_vector_use().
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <1458066895-20632-20-git-send-email-armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
If pci_ivshmem_realize() fails after it created its migration blocker,
the blocker is left in place. Fix that by creating it last.
Likewise, if it fails after it called fifo8_create(), it leaks fifo
memory. Fix that the same way.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <1458066895-20632-18-git-send-email-armbru@redhat.com>
We reuse errp after passing it host_memory_backend_get_memory(). If
both host_memory_backend_get_memory() and the reuse set an error, the
reuse will fail the assertion in error_setv(). Fortunately,
host_memory_backend_get_memory() can't fail.
Pass it &error_abort to make our assumption explicit, and to get the
assertion failure in the right place should it become invalid.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <1458066895-20632-17-git-send-email-armbru@redhat.com>
Yes, the chardev is commonly useless after we read a bad version from
it, but destroying it is inappropriate anyway: the user created it, so
the user should be able to hold on to it as long as he likes. We
don't destroy it on other errors. Screwed up in commit 5105b1d.
Stop reading instead.
Also note QEMU's behavior in ivshmem-spec.txt.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <1458066895-20632-16-git-send-email-armbru@redhat.com>
IVShmemState member eventfd_chr is useless since commit 9940c32. Drop
it.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <1458066895-20632-14-git-send-email-armbru@redhat.com>
This started as an attempt to update ivshmem_device_spec.txt for
clarity, accuracy and completeness while working on its code, and
quickly became a full rewrite. Since the diff would be useless
anyway, I'm using the opportunity to rename the file to
ivshmem-spec.txt.
I tried hard to ensure the new text contradicts neither the old text
nor the code. If the new text contradicts the old text but not the
code, it's probably a bug in the old text. If the new text
contradicts both, its probably a bug in the new text.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <1458066895-20632-11-git-send-email-armbru@redhat.com>
Document missing test: behavior with MSI-X present but not enabled.
For MSI-X, we test and clear the interrupt pending bit before testing
the interrupt. For INTx, we only clear. Change to test and clear for
consistency.
Test MSI-X vector 1 in addition to vector 0.
Improve comments.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <1458066895-20632-10-git-send-email-armbru@redhat.com>
test_ivshmem_server() waits until the first byte in BAR 2 contains the
0x42 we put into shared memory. Works because the byte reads zero
until the device maps the shared memory gotten from the server.
Check the IVPosition register instead: it's initially -1, and becomes
non-negative right when the device maps the share memory, so no
change, just cleaner, because it's what guest software is supposed to
do.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <1458066895-20632-9-git-send-email-armbru@redhat.com>
Test state of registers after reset.
Test reading Interrupt Status clears it.
Test (invalid) read of Doorbell.
Add more comments.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <1458066895-20632-8-git-send-email-armbru@redhat.com>
qpci_pc_iomap() maps BARs one after the other, without padding. This
is wrong. PCI Local Bus Specification Revision 3.0, 6.2.5.1. Address
Maps: "all address spaces used are a power of two in size and are
naturally aligned". That's because the size of a BAR is given by the
number of address bits the device decodes, and the BAR needs to be
mapped at a multiple of that size to ensure the address decoding
works.
Fix qpci_pc_iomap() accordingly. This takes care of a FIXME in
ivshmem-test.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <1458066895-20632-7-git-send-email-armbru@redhat.com>
Event notifiers are designed for eventfd(2). They can fall back to
pipes, but according to Paolo, event_notifier_init_fd() really
requires the real thing, and should therefore be under #ifdef
CONFIG_EVENTFD. Do that.
Its only user is ivshmem, which is currently CONFIG_POSIX. Narrow it
to CONFIG_EVENTFD.
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <1458066895-20632-6-git-send-email-armbru@redhat.com>
For versions of nettle < 3.0.0, the cipher functions took a
'void *ctx' and 'unsigned len' instad of 'const void *ctx'
and 'size_t len'. The xts functions though are builtin to
QEMU and always expect the latter signatures. Define a
second set of wrappers to use with the correct signatures
needed by XTS mode.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Prior to the nettle 3.0.0 release, the cast5_set_key function
was actually named cast128_set_key, so we must add a compatibility
definition.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Commit 125b310e1d ("qemu-ga: move
channel/transport functionality into wrapper class") stopped using the
local err variable in channel_event_cb().
This patch deletes the unused variable.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
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Merge remote-tracking branch 'remotes/armbru/tags/pull-qapi-2016-03-18' into staging
QAPI patches for 2016-03-18
# gpg: Signature made Fri 18 Mar 2016 09:54:57 GMT using RSA key ID EB918653
# gpg: Good signature from "Markus Armbruster <armbru@redhat.com>"
# gpg: aka "Markus Armbruster <armbru@pond.sub.org>"
* remotes/armbru/tags/pull-qapi-2016-03-18:
qapi: Use anonymous bases in QMP flat unions
qapi: Allow anonymous base for flat union
qapi: Make BlockdevOptions doc example closer to reality
qapi: Don't special-case simple union wrappers
qapi: Drop unused c_null()
qapi: Inline gen_visit_members() into lone caller
qapi-commands: Inline single-use helpers of gen_marshal()
qapi-commands: Utilize implicit struct visits
qapi-event: Utilize implicit struct visits
qapi-event: Drop qmp_output_get_qobject() null check
qapi: Emit implicit structs in generated C
qapi: Adjust names of implicit types
qapi: Make c_type() more OO-like
qapi: Fix command with named empty argument type
qapi: Assert in places where variants are not handled
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Option parameter "share" is missing. Without it, you get a *private*
mmap(), which defeats ivshmem's purpose pretty thoroughly ;)
While there, switch to the conventional mountpoint of hugetlbfs
/dev/hugepages.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <1458066895-20632-5-git-send-email-armbru@redhat.com>
Option -m NAME is interpreted as directory name if we can statfs() it
and its on hugetlbfs. Else it's interpreted as POSIX shared memory
object name. This is nuts.
Always interpret -m as directory. Create new -M for POSIX shared
memory. Last of -m or -M wins.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <1458066895-20632-4-git-send-email-armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Burying error messages in ~20 lines of usage help is bad form. Print
a single line pointing to -h instead.
Print -h help to stdout rather than stderr. Fix default of -p. Clean
up the help text a bit.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <1458066895-20632-3-git-send-email-armbru@redhat.com>
The code to find the minimum page size is is vulnerable to TOCTTOU.
Added in commit 2d103aa "target-ppc: fix hugepage support when using
memory-backend-file" (v2.4.0). Since I can't fix it myself right now,
add a FIXME comment.
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <1458066895-20632-2-git-send-email-armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
USB Ehci emulation supports host controller capability registers.
But its mmio '.write' function was missing, which lead to a null
pointer dereference issue. Add a do nothing 'ehci_caps_write'
definition to avoid it; Do nothing because capability registers
are Read Only(RO).
Reported-by: Zuozhi Fzz <zuozhi.fzz@alibaba-inc.com>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Message-id: 1454072434-16045-1-git-send-email-ppandit@redhat.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
inotify_init1 usage was guarded by a check for linux but does not
exist on older distributions like CentOS 5 resulting in build
failures.
Signed-off-by: Matthew Fortune <matthew.fortune@imgtec.com>
Message-id: 6D39441BF12EF246A7ABCE6654B023536BB85D4A@hhmail02.hh.imgtec.org
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
All the callers for xhci_dma_write_u32s() are using mostly 5 * uint32_t
in len. To avoid unbound stack warning for the function, make it
statically allocated, and assert when it's not big enough in the
future.
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-id: 1457661106-9569-1-git-send-email-peterx@redhat.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Mingw-w64 does not provide sys/ioctl.h and Linux builds don't need it,
so remove that include statement.
ERROR is defined by wingdi.h (included via windows.h). Undefine it before
it is redefined to avoid a compiler warning / error.
Signed-off-by: Stefan Weil <sw@weilnetz.de>
Message-id: 1458159439-32322-1-git-send-email-sw@weilnetz.de
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Now that the generator supports it, we might as well use an
anonymous base rather than breaking out a single-use Base
structure, for all three of our current QMP flat unions.
Oddly enough, this change does not affect the resulting
introspection output (because we already inline the members of
a base type into an object, and had no independent use of the
base type reachable from a command).
The case_whitelist now has to list the name of an implicit
type; which is not too bad (consider it a feature if it makes
it harder for developers to make the whitelist grow :)
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1458254921-17042-16-git-send-email-eblake@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Rather than requiring all flat unions to explicitly create
a separate base struct, we can allow the qapi schema to specify
the common members via an inline dictionary. This is similar to
how commands can specify an inline anonymous type for its 'data'.
We already have several struct types that only exist to serve as
a single flat union's base; the next commit will clean them up.
In particular, this patch's change to the BlockdevOptions example
in qapi-code-gen.txt will actually be done in the real QAPI schema.
Now that anonymous bases are legal, we need to rework the
flat-union-bad-base negative test (as previously written, it
forms what is now valid QAPI; tweak it to now provide coverage
of a new error message path), and add a positive test in
qapi-schema-test to use an anonymous base (making the integer
argument optional, for even more coverage).
Note that this patch only allows anonymous bases for flat unions;
simple unions are already enough syntactic sugar that we do not
want to burden them further. Meanwhile, while it would be easy
to also allow an anonymous base for structs, that would be quite
redundant, as the members can be put right into the struct
instead.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1458254921-17042-15-git-send-email-eblake@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Although we don't want to repeat the entire BlockdevOptions
QMP command in the example, it helps if we aren't needlessly
diverging (the initial example was written before we had
committed the actual QMP interface). Use names that match what
is found in qapi/block-core.json, such as '*read-only' rather
than 'readonly', or 'BlockdevRef' rather than 'BlockRef'.
For the simple union example, invent BlockdevOptionsSimple so
that later text is unambiguous which of the two union forms is
meant (telling the user to refer back to two 'BlockdevOptions'
wasn't nice, and QMP has only the flat union form).
Also, mention that the discriminator of a flat union is
non-optional.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1458254921-17042-14-git-send-email-eblake@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Simple unions were carrying a special case that hid their 'data'
QMP member from the resulting C struct, via the hack method
QAPISchemaObjectTypeVariant.simple_union_type(). But by using
the work we started by unboxing flat union and alternate
branches, coupled with the ability to visit the members of an
implicit type, we can now expose the simple union's implicit
type in qapi-types.h:
| struct q_obj_ImageInfoSpecificQCow2_wrapper {
| ImageInfoSpecificQCow2 *data;
| };
|
| struct q_obj_ImageInfoSpecificVmdk_wrapper {
| ImageInfoSpecificVmdk *data;
| };
...
| struct ImageInfoSpecific {
| ImageInfoSpecificKind type;
| union { /* union tag is @type */
| void *data;
|- ImageInfoSpecificQCow2 *qcow2;
|- ImageInfoSpecificVmdk *vmdk;
|+ q_obj_ImageInfoSpecificQCow2_wrapper qcow2;
|+ q_obj_ImageInfoSpecificVmdk_wrapper vmdk;
| } u;
| };
Doing this removes asymmetry between QAPI's QMP side and its
C side (both sides now expose 'data'), and means that the
treatment of a simple union as sugar for a flat union is now
equivalent in both languages (previously the two approaches used
a different layer of dereferencing, where the simple union could
be converted to a flat union with equivalent C layout but
different {} on the wire, or to an equivalent QMP wire form
but with different C representation). Using the implicit type
also lets us get rid of the simple_union_type() hack.
Of course, now all clients of simple unions have to adjust from
using su->u.member to using su->u.member.data; while this touches
a number of files in the tree, some earlier cleanup patches
helped minimize the change to the initialization of a temporary
variable rather than every single member access. The generated
qapi-visit.c code is also affected by the layout change:
|@@ -7393,10 +7393,10 @@ void visit_type_ImageInfoSpecific_member
| }
| switch (obj->type) {
| case IMAGE_INFO_SPECIFIC_KIND_QCOW2:
|- visit_type_ImageInfoSpecificQCow2(v, "data", &obj->u.qcow2, &err);
|+ visit_type_q_obj_ImageInfoSpecificQCow2_wrapper_members(v, &obj->u.qcow2, &err);
| break;
| case IMAGE_INFO_SPECIFIC_KIND_VMDK:
|- visit_type_ImageInfoSpecificVmdk(v, "data", &obj->u.vmdk, &err);
|+ visit_type_q_obj_ImageInfoSpecificVmdk_wrapper_members(v, &obj->u.vmdk, &err);
| break;
| default:
| abort();
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1458254921-17042-13-git-send-email-eblake@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
