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

[Jamie Heilman]

Chen, Tiejun wrote:
> 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.

That doesn't revert cleanly for me, and I don't have much time to
fiddle with it until the 24th---so checked out the commit before it
(d4ae84a0), applied your patch, built, and yes, everything works fine
at that point.  I'll probably have time for another full bisection
later, assuming things aren't ironed out already by then.

-- 
Jamie Heilman                     http://audible.transient.net/~jamie/
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