This reverts commit 4c2c047469.
(2b5c04d82e in stable-9.0 series)
This commit tried to fix a problem with our usage of MMU indexes when
EL3 is AArch32, using what it described as a "more complicated
approach" where we share the same MMU index values for Secure PL1&0
and NonSecure PL1&0. In theory this should work, but the change
didn't account for (at least) two things:
(1) The design change means we need to flush the TLBs at any point
where the CPU state flips from one to the other. We already flush
the TLB when SCR.NS is changed, but we don't flush the TLB when we
take an exception from NS PL1&0 into Mon or when we return from Mon
to NS PL1&0, and the commit didn't add any code to do that.
(2) The ATS12NS* address translate instructions allow Mon code (which
is Secure) to do a stage 1+2 page table walk for NS. I thought this
was OK because do_ats_write() does a page table walk which doesn't
use the TLBs, so because it can pass both the MMU index and also an
ARMSecuritySpace argument we can tell the table walk that we want NS
stage1+2, not S. But that means that all the code within the ptw
that needs to find e.g. the regime EL cannot do so only with an
mmu_idx -- all these functions like regime_sctlr(), regime_el(), etc
would need to pass both an mmu_idx and the security_space, so they
can tell whether this is a translation regime controlled by EL1 or
EL3 (and so whether to look at SCTLR.S or SCTLR.NS, etc).
In particular, because regime_el() wasn't updated to look at the
ARMSecuritySpace it would return 1 even when the CPU was in Monitor
mode (and the controlling EL is 3). This meant that page table walks
in Monitor mode would look at the wrong SCTLR, TCR, etc and would
generally fault when they should not.
Rather than trying to make the complicated changes needed to rescue
the design of 4c2c047469, we revert it in order to instead take the
route that that commit describes as "the most straightforward" fix,
where we add new MMU indexes EL30_0, EL30_3, EL30_3_PAN to correspond
to "Secure PL1&0 at PL0", "Secure PL1&0 at PL1", and "Secure PL1&0 at
PL1 with PAN".
This revert will re-expose the "spurious alignment faults in
Secure PL0" issue #2326; we'll fix it again in the next commit.
Cc: qemu-stable@nongnu.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Tested-by: Thomas Huth <thuth@redhat.com>
Message-id: 20241101142845.1712482-2-peter.maydell@linaro.org
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
(cherry picked from commit 056c5c90c1)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
===========
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>`_
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