Hi Sadoon, thanks for the report! There isn't much to find about this issue yet. One automatic syscaller crash report [1]. On the emulation side there is [2][3].
On the glibc side we have [4][5] adding the use of it with [6] being a fix. All those seem to be in glibc 2.33 - so I'd expect with [6] it should only be issued on power9 which in turn should HW-support the instruction. I was trying to recreate this on power8 and power9 machines. As expected on power8 just nothing happens (the instruction isn't used due to [6]). TBH I first wondered if these Sforza chips [7][8][9] you mentioned are fully identical to a classic IBM p9 box - but I was indeed able to reproduce the issue just fine on an IBM-sold P9 dmesg: [ 1516.438442] Facility 'SCV' unavailable (12), exception at 0x76c9f84c49a0, MSR=900000000280f033 [ 1516.438472] qemu-system-ppc[42884]: illegal instruction (4) at 76c9f84c49a0 nip 76c9f84c49a0 lr 1f12839d9f0 code 1 in libc-2.33.so[76c9f8380000+220000] [ 1516.438489] qemu-system-ppc[42884]: code: e8010010 7c0803a6 4e800020 60420000 7ca42b78 4bffed65 60000000 38210020 [ 1516.438493] qemu-system-ppc[42884]: code: e8010010 7c0803a6 4e800020 60420000 <44000001> 4bffffb8 60000000 60420000 The chip I used for this test is: Model: 2.2 (pvr 004e 1202) Model name: POWER9, altivec supported The syscall this crashes in belongs to the ioctl (gdb) bt #0 __GI___ioctl (fd=<optimized out>, request=536915584) at ../sysdeps/unix/sysv/linux/powerpc/ioctl.c:56 #1 0x00000cb63ef7d9f0 in kvm_vcpu_ioctl (cpu=cpu@entry=0x7d0f48010010, type=type@entry=536915584) at ../../accel/kvm/kvm-all.c:2654 #2 0x00000cb63ef7dbdc in kvm_cpu_exec (cpu=0x7d0f48010010) at ../../accel/kvm/kvm-all.c:2491 #3 0x00000cb63ee78344 in kvm_vcpu_thread_fn (arg=0x7d0f48010010) at ../../accel/kvm/kvm-cpus.c:49 #4 0x00000cb63f1d14bc in qemu_thread_start (args=<optimized out>) at ../../util/qemu-thread-posix.c:521 #5 0x00007d0f4ac69114 in start_thread (arg=0x7d0f23dfe720) at pthread_create.c:473 #6 0x00007d0f4ab755c0 in clone () at ../sysdeps/unix/sysv/linux/powerpc/powerpc64/clone.S:103 And jumping into the code of the __GI___ioctl we can clearly see the scv instruction is indeed there in the executed code path: 0x7ffff66c4984 <__GI___ioctl+292> bl 0x7ffff66c36e8 <__GI___tcgetattr+8> 0x7ffff66c4988 <__GI___ioctl+296> nop 0x7ffff66c498c <__GI___ioctl+300> addi r1,r1,32 0x7ffff66c4990 <__GI___ioctl+304> ld r0,16(r1) 0x7ffff66c4994 <__GI___ioctl+308> mtlr r0 0x7ffff66c4998 <__GI___ioctl+312> blr 0x7ffff66c499c <__GI___ioctl+316> ori r2,r2,0 >0x7ffff66c49a0 <__GI___ioctl+320> scv 0 [1]: https://webcache.googleusercontent.com/search?q=cache:uS0jhPekyqMJ:https://syzkaller-ppc64.appspot.com/text%3Ftag%3DCrashReport%26x%3D17d99883000000+&cd=2&hl=de&ct=clnk&gl=uk [2]: https://git.qemu.org/?p=qemu.git;a=commit;h=3c89b8d6ac5b8728cd7620f9885bd953edd18a11 [3]: https://lists.gnu.org/archive/html/qemu-devel/2021-03/msg05425.html [4]: https://sourceware.org/git/?p=glibc.git;a=commit;h=68ab82f56690ada86ac1e0c46bad06ba189a10ef [5]: https://sourceware.org/git/?p=glibc.git;a=commit;h=41f013cef24884604c303435dd1915be2ea5c0e0 [6]: https://sourceware.org/git/?p=glibc.git;a=commit;h=527c89cd32f8522859f58343be3d3dc8f754b783 [7]: https://wiki.raptorcs.com/wiki/Sforza [8]: https://wiki.raptorcs.com/wiki/Talos_II [9]: https://wiki.raptorcs.com/wiki/POWER9 [10]: https://lwn.net/Articles/822867/ -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1920784 Title: qemu-system-ppc64le fails with kvm acceleration Status in QEMU: New Status in The Ubuntu-power-systems project: New Status in glibc package in Ubuntu: New Status in qemu package in Ubuntu: Confirmed Bug description: (Suspected glibc issue!) qemu-system-ppc64(le) fails when invoked with kvm acceleration with error "illegal instruction" > qemu-system-ppc64(le) -M pseries,accel=kvm Illegal instruction (core dumped) In dmesg: Facility 'SCV' unavailable (12), exception at 0x7624f8134c0c, MSR=900000000280f033 Version-Release number of selected component (if applicable): qemu 5.2.0 Linux kernel 5.11 glibc 2.33 all latest updates as of submitting the bug report How reproducible: Always Steps to Reproduce: 1. Run qemu with kvm acceleration Actual results: Illegal instruction Expected results: Normal VM execution Additional info: The machine is a Raptor Talos II Lite with a Sforza V1 8-core, but was also observed on a Raptor Blackbird with the same processor. This was also observed on Fedora 34 beta, which uses glibc 2.33 Also tested on ArchPOWER (unofficial port of Arch Linux for ppc64le) with glibc 2.33 Fedora 33 and Ubuntu 20.10, both using glibc 2.32 do not have this issue, and downgrading the Linux kernel from 5.11 to 5.4 LTS on ArchPOWER solved the problem. Kernel 5.9 and 5.10 have the same issue when combined with glibc2.33 ProblemType: Bug DistroRelease: Ubuntu 21.04 Package: qemu-system 1:5.2+dfsg-6ubuntu2 ProcVersionSignature: Ubuntu 5.11.0-11.12-generic 5.11.0 Uname: Linux 5.11.0-11-generic ppc64le .sys.firmware.opal.msglog: Error: [Errno 13] Permission denied: '/sys/firmware/opal/msglog' ApportVersion: 2.20.11-0ubuntu60 Architecture: ppc64el CasperMD5CheckResult: pass CurrentDesktop: Unity:Unity7:ubuntu Date: Mon Mar 22 14:48:39 2021 InstallationDate: Installed on 2021-03-22 (0 days ago) InstallationMedia: Ubuntu-Server 21.04 "Hirsute Hippo" - Alpha ppc64el (20210321) KvmCmdLine: COMMAND STAT EUID RUID PID PPID %CPU COMMAND ProcKernelCmdLine: root=UUID=f3d03315-0944-4a02-9c87-09c00eba9fa1 ro ProcLoadAvg: 1.20 0.73 0.46 1/1054 6071 ProcSwaps: Filename Type Size Used Priority /swap.img file 8388544 0 -2 ProcVersion: Linux version 5.11.0-11-generic (buildd@bos02-ppc64el-002) (gcc (Ubuntu 10.2.1-20ubuntu1) 10.2.1 20210220, GNU ld (GNU Binutils for Ubuntu) 2.36.1) #12-Ubuntu SMP Mon Mar 1 19:26:20 UTC 2021 SourcePackage: qemu UpgradeStatus: No upgrade log present (probably fresh install) VarLogDump_list: total 0 acpidump: cpu_cores: Number of cores present = 8 cpu_coreson: Number of cores online = 8 cpu_smt: SMT=4 To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1920784/+subscriptions
