Re: [BUG] x86: failed to boot a kernel on a Ryzen machine

[Borislav Petkov <bp@alien8.de>]

On Mon, Apr 24, 2017 at 10:09:04PM +0900, Satoru Takeuchi wrote:
> At Mon, 24 Apr 2017 14:48:46 +0200,
> Borislav Petkov wrote:
> > 
> > On Mon, Apr 24, 2017 at 09:39:12PM +0900, Satoru Takeuchi wrote:
> > > I used the following auto-test tool (its backend is ktest).
> > > 
> > > https://github.com/satoru-takeuchi/elkdat
> > > 
> > > This problem can be reproduced by the following command on Ubuntu 16.04.
> > > 
> > > ```
> > > $ sudo apt-get install git vagrant libvirt-bin libvirt-dev kernel-package qemu-kvm libssl-dev libncurses5-dev
> > 
> > Can you minimize that reproducer? I.e, can you dump only the qemu
> > command line options from this setup?
> > 
> > They're enough to be able to start a guest with your config without me
> > having to install all that other stuff.
> 
> OK. Is it sufficient information?
> 
> ```
> qemu-system-x86_64 -enable-kvm -name elkdat_ktest -S -machine pc-i440fx-xenial,accel=kvm,usb=off -cpu Opteron_G3,+smap,+adx,+rdseed,+bmi2,+smep,+avx2,+bmi1,+fsgsbase,+perfctr_nb,+perfctr_core,+topoext,+tce,+wdt,+skinit,+osvw,+3dnowprefetch,+cr8legacy,+extapic,+cmp_legacy,+pdpe1gb,+fxsr_opt,+mmxext,+rdrand,+f16c,+avx,+osxsave,+xsave,+aes,+movbe,+sse4.2,+sse4.1,+fma,+ssse3,+pclmuldq,+ht,+vme -m 512 -realtime mlock=off -smp 2,sockets=2,cores=1,threads=1 -uuid 12de0e96-5d01-4ab0-b0b3-165f55999960 -no-user-config -nodefaults -chardev socket,id=charmonitor,path=/var/lib/libvirt/qemu/domain-elkdat_ktest/monitor.sock,server,nowait -mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc -no-shutdown -boot strict=on -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -drive file=/var/lib/libvirt/images/elkdat_ktest.img,format=qcow2,if=none,id=drive-virtio-disk0 -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x3,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1 -netdev tap,fd=26,id=hostnet0,vhost=on,vhostfd=28 -device virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:e4:6f:3e,bus=pci.0,addr=0x5 -chardev pty,id=charserial0 -device isa-serial,chardev=charserial0,id=serial0 -vnc 127.0.0.1:0 -k en-us -device cirrus-vga,id=video0,bus=pci.0,addr=0x2 -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x4 -msg timestamp=on
> ```

Yes, thanks, I was able to reproduce:

[    0.488015] raid6: sse2x1   gen()  2073 MB/s
[    0.560008] raid6: sse2x1   xor()  2670 MB/s
[    0.628022] raid6: sse2x2   gen()  3273 MB/s
[    0.696007] raid6: sse2x2   xor()  3752 MB/s
[    0.764015] raid6: sse2x4   gen()  5532 MB/s
[    0.832009] raid6: sse2x4   xor()  3736 MB/s
[    0.836019] invalid opcode: 0000 [#1] SMP
[    0.838532] Modules linked in:
[    0.840000] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.11.0-rc8 #2
[    0.840000] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.10.2-0-g5f4c7b1-prebuilt.qemu-project.org 04/01/2014
[    0.840000] task: ffff9c01bb828000 task.stack: ffffb1f68031c000
[    0.840000] RIP: 0010:raid6_avx21_gen_syndrome+0x3d/0x120
[    0.840000] RSP: 0018:ffffb1f68031fd78 EFLAGS: 00010246
[    0.840000] RAX: 0000000080000000 RBX: ffffb1f68031fdc8 RCX: 00000000fffedbd9
[    0.840000] RDX: 0000000000000080 RSI: 0000000000001000 RDI: 0000000000000012
[    0.840000] RBP: ffffb1f68031fda8 R08: ffffffff90a7d4e0 R09: 00000000000000f0
[    0.840000] R10: 00000000fffedbc8 R11: 0000000091171001 R12: 0000000000001000
[    0.840000] R13: ffff9c01bb444000 R14: ffff9c01bb445000 R15: 0000000000000012
[    0.840000] FS:  0000000000000000(0000) GS:ffff9c01bec00000(0000) knlGS:0000000000000000
[    0.840000] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    0.840000] CR2: 0000000000000000 CR3: 0000000072e09000 CR4: 00000000003006f0
[    0.840000] Call Trace:
[    0.840000]  raid6_select_algo+0x112/0x30f
[    0.840000]  ? libcrc32c_mod_init+0x2c/0x2c
[    0.840000]  ? set_debug_rodata+0x12/0x12
[    0.840000]  do_one_initcall+0x52/0x1a0
[    0.840000]  ? set_debug_rodata+0x12/0x12
[    0.840000]  kernel_init_freeable+0x178/0x200
[    0.840000]  ? rest_init+0x80/0x80
[    0.840000]  kernel_init+0xe/0x100
[    0.840000]  ret_from_fork+0x2c/0x40
[    0.840000] Code: 55 41 54 53 48 89 d3 48 8d 14 c5 00 00 00 00 41 89 ff 49 89 f4 48 83 ec 08 4c 8b 2c c3 4c 8b 74 13 08 48 89 55 d0 e8 73 ca a9 ff <c5> fd 6f 05 eb 09 4e 00 c5 e5 ef db 4d 85 e4 48 8b 55 d0 0f 84 
[    0.840000] RIP: raid6_avx21_gen_syndrome+0x3d/0x120 RSP: ffffb1f68031fd78
[    0.840009] ---[ end trace 5db62c95950cdfd9 ]---
[    0.844549] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
[    0.844549] 
[    0.848000] ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
[    0.848000]

Looking at CR4: 00000000003006f0, it doesn't have OSXSAVE set. I.e., bit
18. And when that bit is not set, VMOVDQA raises an #UD.

And for some reason qemu doesn't like it even if you request that bit with
+osxsave:

warning: host doesn't support requested feature: CPUID.01H:ECX.osxsave [bit 27]

Even though the corresponding bit in CPUID on the host is set:

0x00000001: EAX=0x00800f00, EBX=0x40200800, ECX=0x7ed8320b, EDX=0x178bfbff
						   ^
Paolo, any thoughts?

-- 
Regards/Gruss,
    Boris.

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