linux-kernel - Re: regression bisected; KVM: entry failed, hardware error 0x80000021

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Message-ID: <5498CB62.3070901@intel.com>
Date:	Tue, 23 Dec 2014 09:54:42 +0800
From:	"Chen, Tiejun" <tiejun.chen@...el.com>
To:	Paolo Bonzini <pbonzini@...hat.com>,
	kvm list <kvm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	luto@...capital.net, jamie@...ible.transient.net
Subject: Re: regression bisected; KVM: entry failed, hardware error 0x80000021

On 2014/12/23 9:50, Chen, Tiejun wrote:
> On 2014/12/22 17:23, Jamie Heilman wrote:
>> Chen, Tiejun wrote:
>>> On 2014/12/21 20:46, Jamie Heilman wrote:
>>>> With v3.19-rc1 when I run qemu-system-x86_64 -machine pc,accel=kvm I
>>>> get:
>>>>
>>>> KVM: entry failed, hardware error 0x80000021
>>>
>>> Looks some MSR writing issues such a failed entry.
>>>
>>>> If you're running a guest on an Intel machine without unrestricted mode
>>>> support, the failure can be most likely due to the guest entering an
>>>> invalid
>>>> state for Intel VT. For example, the guest maybe running in big real
>>>> mode
>>>> which is not supported on less recent Intel processors.
>>>>
>>>> EAX=00000000 EBX=00000000 ECX=00000000 EDX=00000663
>>>> ESI=00000000 EDI=00000000 EBP=00000000 ESP=00000000
>>>> EIP=0000e05b EFL=00010002 [-------] CPL=0 II=0 A20=1 SMM=0 HLT=0
>>>> ES =0000 00000000 0000ffff 00009300
>>>> CS =f000 000f0000 0000ffff 00009b00
>>>> SS =0000 00000000 0000ffff 00009300
>>>> DS =0000 00000000 0000ffff 00009300
>>>> FS =0000 00000000 0000ffff 00009300
>>>> GS =0000 00000000 0000ffff 00009300
>>>> LDT=0000 00000000 0000ffff 00008200
>>>> TR =0000 00000000 0000ffff 00008b00
>>>> GDT=     00000000 0000ffff
>>>> IDT=     00000000 0000ffff
>>>> CR0=60000010 CR2=00000000 CR3=00000000 CR4=00000000
>>>> DR0=0000000000000000 DR1=0000000000000000 DR2=0000000000000000
>>>> DR3=0000000000000000
>>>> DR6=00000000ffff0ff0 DR7=0000000000000400
>>>> EFER=0000000000000000
>>>
>>> And I don't see any obvious wrong as well. Any valuable info from dmesg?
>>
>> With the simple qemu command above, on 3.18.1 I see:
>>
>> kern.info: kvm: zapping shadow pages for mmio generation wraparound
>>
>> when I fire up a full guest that's actually useful I get:
>>
>> kern.info: kvm: zapping shadow pages for mmio generation wraparound
>> kern.err: kvm [4073]: vcpu0 disabled perfctr wrmsr: 0xc1 data 0xffff
>>
>> On 3.18.0-rc3-00042-g34a1cd6 nothing appears in the dmesg, just the
>> message I mention above to stderr.  Same thing with a stock
>> 3.19.0-rc1.  Once I apply your patch the simple test command produces
>> the same zapping shadow pages messages as 3.18.1, and a test guest of
>> a Debian Jessie image (w/stock distro kernel) produces the same thing
>> with disabled perfctr wrmsr message.  However, it doesn't look like
>
> Sorry I'm not sure if I understood current status. Looks 3.19-rc1 & my
> patch just fix that error above,
>
> KVM: entry failed, hardware error 0x80000021
> ...
>
> Right?
>
>> I'm entirely out of the woods, because one of my other guest VMs with a
>> custom kernel that works great under 3.18.1 now fails to run.  Nothing
>> in dmesg, but here's the stderr:
>
> But even you revert 34a1cd60d17 or just apply my patch, something else
> introduced between 3.18.1 and 3.19-rc1 led this error below, right?
>
>>
>> KVM internal error. Suberror: 1
>> emulation failure
>> EAX=000de494 EBX=00000000 ECX=00000000 EDX=00000cfd
>> ESI=00000059 EDI=00000000 EBP=00000000 ESP=00006fb4
>> EIP=000f15c1 EFL=00010016 [----AP-] CPL=0 II=0 A20=1 SMM=0 HLT=0
>> ES =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
>> CS =0008 00000000 ffffffff 00c09b00 DPL=0 CS32 [-RA]
>> SS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
>> DS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
>> FS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
>> GS =0010 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
>> LDT=0000 00000000 0000ffff 00008200 DPL=0 LDT
>> TR =0000 00000000 0000ffff 00008b00 DPL=0 TSS32-busy
>> GDT=     000f6be8 00000037
>> IDT=     000f6c26 00000000
>> CR0=60000011 CR2=00000000 CR3=00000000 CR4=00000000
>> DR0=0000000000000000 DR1=0000000000000000 DR2=0000000000000000
>> DR3=0000000000000000
>> DR6=00000000ffff0ff0 DR7=0000000000000400
>> EFER=0000000000000000
>> Code=e8 ae fc ff ff 89 f2 a8 10 89 d8 75 0a b9 41 15 ff ff ff d1 <5b>
>> 5e c3 5b 5e e9 76 ff ff ff b0 11 e6 20 e6 a0 b0 08 e6 21 b0 70 e6 a1
>> b0 04 e6 21 b0 02
>>
>> FWIW, I get the same thing with 34a1cd60d17 reverted.  Maybe there are
>> two bugs, maybe there's more to this first one.  I can repro this
>
> So if my understanding is correct, this is probably another bug. And
> especially, I already saw the same log in another thread, "Cleaning up
> the KVM clock". Maybe you can continue to `git bisect` to locate that
> bad commit.
>

Looks just now Andy found that commit, 
0e60b0799fedc495a5c57dbd669de3c10d72edd2 "kvm: change memslot sorting 
rule from size to GFN", maybe you can try to revert this to try yours again.

Thanks
Tiejun
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