On 09/11/2016 04:10, Huang, Kai wrote:
> Hi Greg,
>
> Thanks for reporting this issue.
>
> I don't have 4.1.y source code tree at hand but after taking a glance
> looks the commit a3eaa8649e4c6a6afdafaa04b9114fb230617bb1 ("KVM: VMX:
> Fix commit which broke PML") fixes this by removing vmwrite to
> SECONDARY_VM_EXEC_CONTROL in vmx_disable_pml, so yes I think this commit
> can fix this issue.
>
> But I think you probably need another commit to fix potential vmwrite
> error when creating vcpu: 4e59516a12a6ef6dcb660cb3a3f70c64bd60cfec (kvm:
> vmx: ensure VMCS is current while enabling PML). Peter found and fixed
> this issue, so I also added him to cc-list.
>
> Paolo/Radim, please comment if I made mistake here.
Yes, we should backport both of them. Greg, can you test it? Then I'll
send the two patches to linux-stable.
Paolo
> Thanks,
> -Kai
>
> On 11/9/2016 1:17 PM, Greg Edwards wrote:
>> On current 4.1.y stable kernel (4.1.35) on a Broadwell-EP system, I
>> see the
>> following when shutting down a multiple vcpu VM:
>>
>> [ 758.387722] vmwrite error: reg 401e value a9 (err 1)
>> [ 758.392860] CPU: 33 PID: 14969 Comm: qemu-system-x86 Not tainted
>> 4.1.35 #1
>> [ 758.399897] Hardware name: DDN 14000x/14000, BIOS 0229 09/23/2016
>> [ 758.406156] 0000000000000286 0000000028b15def ffff88202f3fbb38
>> ffffffff8159de63
>> [ 758.413942] ffff88402a938000 0000000000000001 ffff88202f3fbb48
>> ffffffffa060fa1c
>> [ 758.421736] ffff88202f3fbb58 ffffffffa060fa49 ffff88202f3fbb78
>> ffffffffa0618fab
>> [ 758.429534] Call Trace:
>> [ 758.432147] [<ffffffff8159de63>] dump_stack+0x4d/0x63
>> [ 758.437449] [<ffffffffa060fa1c>] vmwrite_error+0x2c/0x30 [kvm_intel]
>> [ 758.444059] [<ffffffffa060fa49>] vmcs_writel+0x29/0x30 [kvm_intel]
>> [ 758.450493] [<ffffffffa0618fab>] vmx_free_vcpu+0xdb/0xf0 [kvm_intel]
>> [ 758.457111] [<ffffffffa059ddb8>] kvm_arch_vcpu_free+0x48/0x50 [kvm]
>> [ 758.463637] [<ffffffffa059eb8a>] kvm_arch_destroy_vm+0x10a/0x200
>> [kvm]
>> [ 758.470418] [<ffffffff810caff8>] ? synchronize_srcu+0x28/0x30
>> [ 758.476419] [<ffffffffa05850c5>] kvm_put_kvm+0x105/0x220 [kvm]
>> [ 758.482505] [<ffffffffa0585218>] kvm_vcpu_release+0x18/0x20 [kvm]
>> [ 758.488853] [<ffffffff811a143b>] __fput+0xcb/0x1d0
>> [ 758.493899] [<ffffffff811a158e>] ____fput+0xe/0x10
>> [ 758.498939] [<ffffffff81098ec4>] task_work_run+0xd4/0xf0
>> [ 758.504497] [<ffffffff8107d811>] do_exit+0x2a1/0xb40
>> [ 758.509708] [<ffffffff8107eef7>] do_group_exit+0x47/0xc0
>> [ 758.515269] [<ffffffff8108adc3>] get_signal+0x1f3/0x6c0
>> [ 758.520743] [<ffffffff81003517>] do_signal+0x37/0x800
>> [ 758.526042] [<ffffffff810e9c35>] ? SyS_futex+0x85/0x1a0
>> [ 758.531513] [<ffffffff81003d50>] do_notify_resume+0x70/0x80
>> [ 758.537334] [<ffffffff815a4882>] int_signal+0x12/0x17
>>
>> This started with the inclusion of
>> 6c2ca21665b99ce2f76389c353b985d8195387cc
>> ("KVM: nVMX: Fix memory corruption when using VMCS shadowing") in 4.1.31.
>>
>> The error is coming out of vmx_disable_pml() when freeing the 2nd and
>> subsequent vcpus, as SECONDARY_EXEC_ENABLE_PML was already cleared
>> from the
>> SECONDARY_VM_EXEC_CONTROL when the first vcpu was freed.
>>
>> Additionally pulling back a3eaa8649e4c6a6afdafaa04b9114fb230617bb1
>> ("KVM: VMX:
>> Fix commit which broke PML") from 4.4 resolves it for me, as it fixes
>> the above condition.
>>
>> Is this the correct fix for 4.1.y?
>>
>> Greg
>>
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