3a45f4f537
The code for powering on a CPU in arm-powerctl.c has two separate
use cases:
* emulation of a real hardware power controller
* emulation of firmware interfaces (primarily PSCI) with
CPU on/off APIs
For the first case, we only need to reset the CPU and set its
starting PC and X0. For the second case, because we're emulating the
firmware we need to ensure that it's in the state that the firmware
provides. In particular, when we reset to a lower EL than the
highest one we are emulating, we need to put the CPU into a state
that permits correct running at that lower EL. We already do a
little of this in arm-powerctl.c (for instance we set SCR_HCE to
enable the HVC insn) but we don't do enough of it. This means that
in the case where we are emulating EL3 but also providing emulated
PSCI the guest will crash when a secondary core tries to use a
feature that needs an SCR_EL3 bit to be set, such as MTE or PAuth.
The hw/arm/boot.c code also has to support this "start guest code in
an EL that's lower than the highest emulated EL" case in order to do
direct guest kernel booting; it has all the necessary initialization
code to set the SCR_EL3 bits. Pull the relevant boot.c code out into
a separate function so we can share it between there and
arm-powerctl.c.
This refactoring has a few code changes that look like they
might be behaviour changes but aren't:
* if info->secure_boot is false and info->secure_board_setup is
true, then the old code would start the first CPU in Hyp
mode but without changing SCR.NS and NSACR.{CP11,CP10}.
This was wrong behaviour because there's no such thing
as Secure Hyp mode. The new code will leave the CPU in SVC.
(There is no board which sets secure_boot to false and
secure_board_setup to true, so this isn't a behaviour
change for any of our boards.)
* we don't explicitly clear SCR.NS when arm-powerctl.c
does a CPU-on to EL3. This was a no-op because CPU reset
will reset to NS == 0.
And some real behaviour changes:
* we no longer set HCR_EL2.RW when booting into EL2: the guest
can and should do that themselves before dropping into their
EL1 code. (arm-powerctl and boot did this differently; I
opted to use the logic from arm-powerctl, which only sets
HCR_EL2.RW when it's directly starting the guest in EL1,
because it's more correct, and I don't expect guests to be
accidentally depending on our having set the RW bit for them.)
* if we are booting a CPU into AArch32 Secure SVC then we won't
set SCR.HCE any more. This affects only the vexpress-a15 and
raspi2b machine types. Guests booting in this case will either:
- be able to set SCR.HCE themselves as part of moving from
Secure SVC into NS Hyp mode
- will move from Secure SVC to NS SVC, and won't care about
behaviour of the HVC insn
- will stay in Secure SVC, and won't care about HVC
* on an arm-powerctl CPU-on we will now set the SCR bits for
pauth/mte/sve/sme/hcx/fgt features
The first two of these are very minor and I don't expect guest
code to trip over them, so I didn't judge it worth convoluting
the code in an attempt to keep exactly the same boot.c behaviour.
The third change fixes issue 1899.
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1899
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20230926155619.4028618-1-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>`_