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ivshmem can be configured with and without interrupt capability
(a.k.a. "doorbell"). The two configurations have largely disjoint
options, which makes for a confusing (and badly checked) user
interface. Moreover, the device can't tell the guest whether its
doorbell is enabled.
Create two new device models ivshmem-plain and ivshmem-doorbell, and
deprecate the old one.
Changes from ivshmem:
* PCI revision is 1 instead of 0. The new revision is fully backwards
compatible for guests. Guests may elect to require at least
revision 1 to make sure they're not exposed to the funny "no shared
memory, yet" state.
* Property "role" replaced by "master". role=master becomes
master=on, role=peer becomes master=off. Default is off instead of
auto.
* Property "use64" is gone. The new devices always have 64 bit BARs.
Changes from ivshmem to ivshmem-plain:
* The Interrupt Pin register in PCI config space is zero (does not use
an interrupt pin) instead of one (uses INTA).
* Property "x-memdev" is renamed to "memdev".
* Properties "shm" and "size" are gone. Use property "memdev"
instead.
* Property "msi" is gone. The new device can't have MSI-X capability.
It can't interrupt anyway.
* Properties "ioeventfd" and "vectors" are gone. They're meaningless
without interrupts anyway.
Changes from ivshmem to ivshmem-doorbell:
* Property "msi" is gone. The new device always has MSI-X capability.
* Property "ioeventfd" defaults to on instead of off.
* Property "size" is gone. The new device can only map all the shared
memory received from the server.
Guests can easily find out whether the device is configured for
interrupts by checking for MSI-X capability.
Note: some code added in sub-optimal places to make the diff easier to
review. The next commit will move it to more sensible places.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <1458066895-20632-37-git-send-email-armbru@redhat.com>
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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>
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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>
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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>
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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>
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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>
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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>
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Clean up includes so that osdep.h is included first and headers
which it implies are not included manually.
This commit was created with scripts/clean-includes.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
Tested-by: Eric Blake <eblake@redhat.com>
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Recent commit 660c97ee introduced a regression in irq case, make
sure this code path is also tested.
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
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Add a cleanup_vm() function to free QPCIDevice & QPCIBus when cleaning
up the IVState.
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
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The device's guest interface and its QEMU user interface are
flawed^Whotly debated. We'll resolve that in the next development
cycle, probably by deprecating the device in favour of a cleaned up,
but not quite compatible revision.
To avoid adding more baggage to the soon-to-be-deprecated interface,
mark property "memdev" as experimental, by renaming it to "x-memdev".
It's the only recent user interface change.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <1448384789-14830-6-git-send-email-armbru@redhat.com>
[Update of qemu-doc.texi squashed in]
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
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If the device isn't found, the assertion uses dev without
initialization. Fix that.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <1448384789-14830-4-git-send-email-armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
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Some tests may take long to run, move them under g_test_slow()
condition.
The 5s timeout for the "server" test will have to be adjusted to the worst
known time (for the records, it takes ~0.2s on my host). The "pair"
test takes ~1.7, a quickest version could be implemented.
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-id: 1447326618-11686-1-git-send-email-marcandre.lureau@redhat.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
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Instead of handling allocation, teach ivshmem to use a memory backend.
This allows to use hugetlbfs backed memory now.
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Claudio Fontana <claudio.fontana@huawei.com>
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Adds 4 ivshmemtests:
- single qemu instance and basic IO
- pair of instances, check memory sharing
- pair of instances with server, and MSIX
- hot plug/unplug
A temporary shm is created as well as a directory to place server
socket, both should be clear on exit and abort.
Cc: Cam Macdonell <cam@cs.ualberta.ca>
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Claudio Fontana <claudio.fontana@huawei.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>
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Note that it launches two instances, as sharing memory is the purpose of
ivshmem.
Cc: Cam Macdonell <cam@cs.ualberta.ca>
Cc: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>
[ Remove Nahanni codename, add test to pci set - Marc-André ]
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
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