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101f27f3c8
The logic of gicv3_redist_update() is as follows:
* it must be called in any code path that changes the state of
(only) redistributor interrupts
* if it finds a redistributor interrupt that is (now) higher
priority than the previous highest-priority pending interrupt,
then this must be the new highest-priority pending interrupt
* if it does *not* find a better redistributor interrupt, then:
- if the previous state was "no interrupts pending" then
the new state is still "no interrupts pending"
- if the previous best interrupt was not a redistributor
interrupt then that remains the best interrupt
- if the previous best interrupt *was* a redistributor interrupt,
then the new best interrupt must be some non-redistributor
interrupt, but we don't know which so must do a full scan
In commit 17fb5e36aabd4b2c125 we effectively added the LPI interrupts
as a kind of "redistributor interrupt" for this purpose, by adding
cs->hpplpi to the set of things that gicv3_redist_update() considers
before it gives up and decides to do a full scan of distributor
interrupts. However we didn't quite get this right:
* the condition check for "was the previous best interrupt a
redistributor interrupt" must be updated to include LPIs
in what it considers to be redistributor interrupts
* every code path which updates the LPI state which
gicv3_redist_update() checks must also call gicv3_redist_update():
this is cs->hpplpi and the GICR_CTLR ENABLE_LPIS bit
This commit fixes this by:
* correcting the test on cs->hppi.irq in gicv3_redist_update()
* making gicv3_redist_update_lpi() always call gicv3_redist_update()
* introducing a new gicv3_redist_update_lpi_only() for the one
callsite (the post-load hook) which must not call
gicv3_redist_update()
* making gicv3_redist_lpi_pending() always call gicv3_redist_update(),
either directly or via gicv3_redist_update_lpi()
* removing a couple of now-unnecessary calls to gicv3_redist_update()
from some callers of those two functions
* calling gicv3_redist_update() when the GICR_CTLR ENABLE_LPIS
bit is cleared
(This means that the not-file-local gicv3_redist_* LPI related
functions now all take care of the updates of internally cached
GICv3 information, in the same way the older functions
gicv3_redist_set_irq() and gicv3_redist_send_sgi() do.)
The visible effect of this bug was that when the guest acknowledged
an LPI by reading ICC_IAR1_EL1, we marked it as not pending in the
LPI data structure but still left it in cs->hppi so we would offer it
to the guest again. In particular for setups using an emulated GICv3
and ITS and using devices which use LPIs (ie PCI devices) a Linux
guest would complain "irq 54: nobody cared" and then hang. (The hang
was intermittent, presumably depending on the timing between
different interrupts arriving and being completed.)
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-id: 20211124202005.989935-1-peter.maydell@linaro.org
=========== QEMU README =========== QEMU is a generic and open source machine & userspace emulator and virtualizer. QEMU is capable of emulating a complete machine in software without any need for hardware virtualization support. By using dynamic translation, it achieves very good performance. QEMU can also integrate with the Xen and KVM hypervisors to provide emulated hardware while allowing the hypervisor to manage the CPU. With hypervisor support, QEMU can achieve near native performance for CPUs. When QEMU emulates CPUs directly it is capable of running operating systems made for one machine (e.g. an ARMv7 board) on a different machine (e.g. an x86_64 PC board). QEMU is also capable of providing userspace API virtualization for Linux and BSD kernel interfaces. This allows binaries compiled against one architecture ABI (e.g. the Linux PPC64 ABI) to be run on a host using a different architecture ABI (e.g. the Linux x86_64 ABI). This does not involve any hardware emulation, simply CPU and syscall emulation. QEMU aims to fit into a variety of use cases. It can be invoked directly by users wishing to have full control over its behaviour and settings. It also aims to facilitate integration into higher level management layers, by providing a stable command line interface and monitor API. It is commonly invoked indirectly via the libvirt library when using open source applications such as oVirt, OpenStack and virt-manager. QEMU as a whole is released under the GNU General Public License, version 2. For full licensing details, consult the LICENSE file. Documentation ============= Documentation can be found hosted online at `<https://www.qemu.org/documentation/>`_. The documentation for the current development version that is available at `<https://www.qemu.org/docs/master/>`_ is generated from the ``docs/`` folder in the source tree, and is built by `Sphinx <https://www.sphinx-doc.org/en/master/>_`. Building ======== QEMU is multi-platform software intended to be buildable on all modern Linux platforms, OS-X, Win32 (via the Mingw64 toolchain) and a variety of other UNIX targets. The simple steps to build QEMU are: .. code-block:: shell mkdir build cd build ../configure make Additional information can also be found online via the QEMU website: * `<https://wiki.qemu.org/Hosts/Linux>`_ * `<https://wiki.qemu.org/Hosts/Mac>`_ * `<https://wiki.qemu.org/Hosts/W32>`_ Submitting patches ================== The QEMU source code is maintained under the GIT version control system. .. code-block:: shell git clone https://gitlab.com/qemu-project/qemu.git When submitting patches, one common approach is to use 'git format-patch' and/or 'git send-email' to format & send the mail to the qemu-devel@nongnu.org mailing list. All patches submitted must contain a 'Signed-off-by' line from the author. Patches should follow the guidelines set out in the `style section <https://www.qemu.org/docs/master/devel/style.html>` of the Developers Guide. Additional information on submitting patches can be found online via the QEMU website * `<https://wiki.qemu.org/Contribute/SubmitAPatch>`_ * `<https://wiki.qemu.org/Contribute/TrivialPatches>`_ The QEMU website is also maintained under source control. .. code-block:: shell git clone https://gitlab.com/qemu-project/qemu-web.git * `<https://www.qemu.org/2017/02/04/the-new-qemu-website-is-up/>`_ A 'git-publish' utility was created to make above process less cumbersome, and is highly recommended for making regular contributions, or even just for sending consecutive patch series revisions. It also requires a working 'git send-email' setup, and by default doesn't automate everything, so you may want to go through the above steps manually for once. For installation instructions, please go to * `<https://github.com/stefanha/git-publish>`_ The workflow with 'git-publish' is: .. code-block:: shell $ git checkout master -b my-feature $ # work on new commits, add your 'Signed-off-by' lines to each $ git publish Your patch series will be sent and tagged as my-feature-v1 if you need to refer back to it in the future. Sending v2: .. code-block:: shell $ git checkout my-feature # same topic branch $ # making changes to the commits (using 'git rebase', for example) $ git publish Your patch series will be sent with 'v2' tag in the subject and the git tip will be tagged as my-feature-v2. Bug reporting ============= The QEMU project uses GitLab issues to track bugs. Bugs found when running code built from QEMU git or upstream released sources should be reported via: * `<https://gitlab.com/qemu-project/qemu/-/issues>`_ If using QEMU via an operating system vendor pre-built binary package, it is preferable to report bugs to the vendor's own bug tracker first. If the bug is also known to affect latest upstream code, it can also be reported via GitLab. For additional information on bug reporting consult: * `<https://wiki.qemu.org/Contribute/ReportABug>`_ ChangeLog ========= For version history and release notes, please visit `<https://wiki.qemu.org/ChangeLog/>`_ or look at the git history for more detailed information. Contact ======= The QEMU community can be contacted in a number of ways, with the two main methods being email and IRC * `<mailto:qemu-devel@nongnu.org>`_ * `<https://lists.nongnu.org/mailman/listinfo/qemu-devel>`_ * #qemu on irc.oftc.net Information on additional methods of contacting the community can be found online via the QEMU website: * `<https://wiki.qemu.org/Contribute/StartHere>`_