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x86: 0.938
device: 0.765
architecture: 0.762
socket: 0.608
mistranslation: 0.606
ppc: 0.580
hypervisor: 0.572
semantic: 0.565
performance: 0.560
debug: 0.541
user-level: 0.534
register: 0.533
i386: 0.531
graphic: 0.530
risc-v: 0.523
files: 0.519
vnc: 0.506
virtual: 0.495
peripherals: 0.485
network: 0.461
assembly: 0.460
PID: 0.453
VMM: 0.451
arm: 0.424
permissions: 0.421
boot: 0.421
kernel: 0.420
TCG: 0.374
KVM: 0.160
Qemu does not force SSE data alignment
I have an OS that tries to use SSE operations. It works fine in qemu. But it crashes when I try to run the OS at the host cpu using KVM.
The instruction that crahes with #GP(0) is
movaps ADDR,%xmm0
The documentation says ADDR has to be 16-bytes alignment otherwise #GP is generated. And indeed the problem was with the data alignment. After adjusting it at my side the OS works fine both with Qemu and KVM.
It would be great if QEMU followed specification more closely and forced SSE data alignment requirements. It will help to catch alignment issues early and debug it easier.
$ qemu-system-x86_64 -version
QEMU emulator version 2.9.50 (v2.9.0-1363-g95eef1c68b)
Copyright (c) 2003-2017 Fabrice Bellard and the QEMU Project developers
The QEMU project is currently considering to move its bug tracking to another system. For this we need to know which bugs are still valid and which could be closed already. Thus we are setting older bugs to "Incomplete" now.
If you still think this bug report here is valid, then please switch the state back to "New" within the next 60 days, otherwise this report will be marked as "Expired". Thank you and sorry for the inconvenience.
I am currently running into this bug on QEMU emulator version 5.1.0.
movaps unaligned access works fine in qemu, when it should throw a GP. Likewise, the same code on physical hardware throws a GP.
Yep. Long-standing bug.
This is an automated cleanup. This bug report has been moved to QEMU's
new bug tracker on gitlab.com and thus gets marked as 'expired' now.
Please continue with the discussion here:
https://gitlab.com/qemu-project/qemu/-/issues/217
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