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hw/arm/smmuv3: Advertise support for SMMUv3.2-BBML2
Peter Maydell authored 
The Arm SMMUv3 includes an optional feature equivalent to the CPU
FEAT_BBM, which permits an OS to switch a range of memory between
"covered by a huge page" and "covered by a sequence of normal pages"
without having to engage in the traditional 'break-before-make'
dance. (This is particularly important for the SMMU, because devices
performing I/O through an SMMU are less likely to be able to cope with
the window in the sequence where an access results in a translation
fault.)  The SMMU spec explicitly notes that one of the valid ways to
be a BBM level 2 compliant implementation is:
 * if there are multiple entries in the TLB for an address,
   choose one of them and use it, ignoring the others

Our SMMU TLB implementation (unlike our CPU TLB) does allow multiple
TLB entries for an address, because the translation table level is
part of the SMMUIOTLBKey, and so our IOTLB hashtable can include
entries for the same address where the leaf was at different levels
(i.e. both hugepage and normal page). Our TLB lookup implementation in
smmu_iotlb_lookup() will always find the entry with the lowest level
(i.e. it prefers the hugepage over the normal page) and ignore any
others. TLB invalidation correctly removes all TLB entries matching
the specified address or address range (unless the guest specifies the
leaf level explicitly, in which case it gets what it asked for). So we
can validly advertise support for BBML level 2.

Note that we still can't yet advertise ourselves as an SMMU v3.2,
because v3.2 requires support for the S2FWB feature, which we don't
yet implement.

Signed-off-by: default avatarPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: default avatarRichard Henderson <richard.henderson@linaro.org>
Reviewed-by: default avatarEric Auger <eric.auger@redhat.com>
Message-id: 20220426160422.2353158-4-peter.maydell@linaro.org
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tcg
tests
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COPYING
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Kconfig
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MAINTAINERS
Makefile
README.rst
VERSION
block.c
blockdev-nbd.c
blockdev.c
blockjob.c
configure
cpu.c
cpus-common.c
disas.c
gdbstub.c
gitdm.config
hmp-commands-info.hx
hmp-commands.hx
iothread.c
job-qmp.c
job.c
memory_ldst.c.inc
meson.build
meson_options.txt
module-common.c
os-posix.c
os-win32.c
page-vary-common.c
README.rst

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:

mkdir build
cd build
../configure
make

Additional information can also be found online via the QEMU website:

Submitting patches

The QEMU source code is maintained under the GIT version control system.

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

The QEMU website is also maintained under source control.

git clone https://gitlab.com/qemu-project/qemu-web.git

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

The workflow with 'git-publish' is:

$ 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:

$ 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:

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:

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

Information on additional methods of contacting the community can be found online via the QEMU website: