On Fri, 19 Apr 2024 at 18:36, Ard Biesheuvel <a...@kernel.org> wrote: > > On Fri, 19 Apr 2024 at 18:09, Jonathan Cameron via groups.io > <jonathan.cameron=huawei....@groups.io> wrote: > > > > On Fri, 19 Apr 2024 13:52:07 +0200 > > Gerd Hoffmann <kra...@redhat.com> wrote: > > > > > Hi, > > > > > > > Gerd, any ideas? Maybe I needs something subtly different in my > > > > edk2 build? I've not looked at this bit of the qemu infrastructure > > > > before - is there a document on how that image is built? > > > > > > There is roms/Makefile for that. > > > > > > make -C roms help > > > make -C roms efi > > > > > > So easiest would be to just update the edk2 submodule to what you > > > need, then rebuild. > > > > > > The build is handled by the roms/edk2-build.py script, > > > with the build configuration being in roms/edk2-build.config. > > > That is usable outside the qemu source tree too, i.e. like this: > > > > > > python3 /path/to/qemu.git/roms/edk2-build.py \ > > > --config /path/to/qemu.git/roms/edk2-build.config \ > > > --core /path/to/edk2.git \ > > > --match armvirt \ > > > --silent --no-logs > > > > > > That'll try to place the images build in "../pc-bios", so maybe better > > > work with a copy of the config file where you adjust this. > > > > > > HTH, > > > Gerd > > > > > > > Thanks Gerd! > > > > So the builds are very similar via the two method... > > However - the QEMU build sets -D CAVIUM_ERRATUM_27456=TRUE > > > > And that's the difference - with that set for my other builds the alignment > > problems go away... > > > > Any idea why we have that set in roms/edk2-build.config? > > Superficially it seems rather unlikely anyone cares about thunderx1 > > (if they do we need to get them some new hardware with fresh bugs) > > bugs now and this config file was only added last year. > > > > > > However, the last comment in Ard's commit message below seems > > highly likely to be relevant! > > > > Chasing through Ard's patch it has the side effect of dropping > > an override of a requirement for strict alignment. > > So with out the errata > > DEFINE GCC_AARCH64_CC_XIPFLAGS = -mstrict-align -mgeneral-regs-only > > is replaced with > > [BuildOptions] > > +!if $(CAVIUM_ERRATUM_27456) == TRUE^M > > + GCC:*_*_AARCH64_PP_FLAGS = -DCAVIUM_ERRATUM_27456^M > > +!else^M > > GCC:*_*_AARCH64_CC_XIPFLAGS == > > +!endif^M > > > > The edk2 commit that added this was the following +CC Ard. > > > > Given I wasn't sure of the syntax of that file I set it > > manually to the original value and indeed it works. > > > > > > commit ec54ce1f1ab41b92782b37ae59e752fff0ef9c41 > > Author: Ard Biesheuvel <a...@kernel.org> > > Date: Wed Jan 4 16:51:35 2023 +0100 > > > > ArmVirtPkg/ArmVirtQemu: Avoid early ID map on ThunderX > > > > The early ID map used by ArmVirtQemu uses ASID scoped non-global > > mappings, as this allows us to switch to the permanent ID map seamlessly > > without the need for explicit TLB maintenance. > > > > However, this triggers a known erratum on ThunderX, which does not > > tolerate non-global mappings that are executable at EL1, as this appears > > to result in I-cache corruption. (Linux disables the KPTI based Meltdown > > mitigation on ThunderX for the same reason) > > > > So work around this, by detecting the CPU implementor and part number, > > and proceeding without the early ID map if a ThunderX CPU is detected. > > > > Note that this requires the C code to be built with strict alignment > > again, as we may end up executing it with the MMU and caches off. > > > > Signed-off-by: Ard Biesheuvel <a...@kernel.org> > > Acked-by: Laszlo Ersek <ler...@redhat.com> > > Tested-by: dann frazier <dann.fraz...@canonical.com> > > > > Test case is > > qemu-system-aarch64 -M virt,virtualization=true, -m 4g -cpu cortex-a76 \ > > -bios QEMU_EFI.fd -d int > > > > Which gets alignment faults since: > > https://lore.kernel.org/all/20240301204110.656742-6-richard.hender...@linaro.org/ > > > > So my feeling here is EDK2 should either have yet another config for QEMU > > as a host > > or should always set the alignment without needing to pick the CAVIUM 27456 > > errata > > which I suspect will get dropped soonish anyway if anyone ever cleans up > > old errata. > > > > This code was never really intended for execution at EL2, but it > happened to work, partially because TCG's lack of strict alignment > checking when the MMU is off. > > Those assumptions no longer hold, so yes, let's get this fixed properly. > > Given VHE and nested virt (which will likely imply VHE in practice), I > would like to extend this functionality (i.e., the use of preliminary > page tables in NOR flash) to EL2 as well, but with VHE enabled. This > means we can still elide TLB maintenance (and BBM checks) by using > different ASIDs, and otherwise, fall back to entering with the MMU off > if VHE is not available. In that case, we should enforce strict > alignment too, so that needs to be fixed regardless. > > I'll try to code something up and send it round. In the mean time, > feel free to propose a minimal patch that reinstates the strict > alignment if you are pressed for time, and I'll merge it right away.
Actually, let's just so that first - I'll send out a patch. -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#118036): https://edk2.groups.io/g/devel/message/118036 Mute This Topic: https://groups.io/mt/105602816/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
