Re: kvm: warning in kvm_load_guest_fpu

[Wanpeng Li]

2017-05-10 9:48 GMT+08:00 Wanpeng Li <kernellwp@xxxxxxxxx>:
> 2017-05-09 22:04 GMT+08:00 Andrey Konovalov <andreyknvl@xxxxxxxxxx>:
>> Hi,
>>
>> I've got the following error report while fuzzing the kernel with syzkaller.
>>
>> On commit 2868b2513aa732a99ea4a0a6bf10dc93c1f3dac2 (4.11+).
>>
>> A reproducer and .config are attached.
>
> If there are beauty codes for testing?

It messes the MXCSR Register reserve bits, I will make a patch.

Regards,
Wanpeng Li

>
>>
>> ------------[ cut here ]------------
>> WARNING: CPU: 0 PID: 4108 at ./arch/x86/include/asm/fpu/internal.h:169
>> kvm_load_guest_fpu.part.163+0x2a9/0x430
>> Modules linked in:
>> CPU: 0 PID: 4108 Comm: a.out Not tainted 4.11.0+ #331
>> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
>> task: ffff880068b2c200 task.stack: ffff880069210000
>> RIP: 0010:copy_kernel_to_fxregs ./arch/x86/include/asm/fpu/internal.h:169
>> RIP: 0010:__copy_kernel_to_fpregs ./arch/x86/include/asm/fpu/internal.h:459
>> RIP: 0010:kvm_load_guest_fpu.part.163+0x2a9/0x430 arch/x86/kvm/x86.c:7596
>> RSP: 0018:ffff8800692176e8 EFLAGS: 00010297
>> RAX: ffff880068b2c200 RBX: 1ffff1000d242edd RCX: ffff8800696fc5ec
>> RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff880068b2d4c5
>> RBP: ffff8800692177b0 R08: 1ffff1000d242ebf R09: 00000000fffff8f8
>> R10: 0000000000000000 R11: 0000000000000002 R12: ffff8800696f8000
>> R13: ffff880069217788 R14: dffffc0000000000 R15: ffff8800696f8000
>> FS:  00007fb239f787c0(0000) GS:ffff88006ca00000(0000) knlGS:0000000000000000
>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> CR2: 000000002001f000 CR3: 000000006c55a000 CR4: 00000000000026f0
>> Call Trace:
>>  kvm_load_guest_fpu arch/x86/kvm/x86.c:6737
>>  vcpu_enter_guest arch/x86/kvm/x86.c:6842
>>  vcpu_run arch/x86/kvm/x86.c:7030
>>  kvm_arch_vcpu_ioctl_run+0x1f61/0x4860 arch/x86/kvm/x86.c:7191
>>  kvm_vcpu_ioctl+0x673/0x1120 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2568
>>  vfs_ioctl fs/ioctl.c:45
>>  do_vfs_ioctl+0x1bf/0x1660 fs/ioctl.c:685
>>  SYSC_ioctl fs/ioctl.c:700
>>  SyS_ioctl+0x8f/0xc0 fs/ioctl.c:691
>>  entry_SYSCALL_64_fastpath+0x1f/0xbe arch/x86/entry/entry_64.S:204
>> RIP: 0033:0x7fb23968bb79
>> RSP: 002b:00007ffec57db2d8 EFLAGS: 00000202 ORIG_RAX: 0000000000000010
>> RAX: ffffffffffffffda RBX: 00007ffec57db480 RCX: 00007fb23968bb79
>> RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000005
>> RBP: 0000000000400b40 R08: 0000000000000000 R09: 0000000000000000
>> R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000
>> R13: 00007ffec57db480 R14: 0000000000000000 R15: 0000000000000000
>> Code: 4e 00 65 ff 0d f9 72 f5 7e e9 5c fe ff ff e8 7f e4 4e 00 31 c0
>> 49 0f ae 8c 24 00 0b 00 00 85 c0 0f 84 35 fe ff ff e8 67 e4 4e 00 <0f>
>> ff e9 29 fe ff ff e8 5b e4 4e 00 65 ff 05 c4 72 f5 7e 4d 8d
>> ---[ end trace 7a89c6ce24f92b9b ]---