[Bug 63121] New: The guest will hang after live migration.

[Bug 63121] New: The guest will hang after live migration.

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=63121

            Bug ID: 63121
           Summary: The guest will hang after live migration.
           Product: Virtualization
           Version: unspecified
    Kernel Version: 3.12.0-rc2
          Hardware: All
                OS: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: kvm
          Assignee: virtualization_kvm@kernel-bugs.osdl.org
          Reporter: chao.zhou@intel.com
        Regression: No

Environment:
------------
Host OS (ia32/ia32e/IA64):ia32e
Guest OS (ia32/ia32e/IA64):ia32e
Guest OS Type (Linux/Windows):Linux
kvm.git Commit:7854cbca815562a49d50bbc6f31599312853d1f4
qemu.git Commit:1cdae4573d7613149348d834c605bfbe3c7d405b
Host Kernel Version:3.12.0-rc2


Bug detailed description:
--------------------------
after guest live migration, the guest will hang, and in command line some
message about "KVM: entry failed, hardware error 0x80000021" will print

note:
1. after guest save/restore, the guest will hang
2. This should be a kernel bug
kvm      + qemu     =  result
7854cbca + 1cdae457 =  bad
2f303b74 + 1cdae457 =  good

Reproduce steps:
----------------
1.Start a TCP daemon for migration
qemu-system-x86_64 -enable-kvm -m 2048 -smp 2 -net none /root/rhel6u4.qcow
2. create guest
qemu-system-x86_64 -enable-kvm -m 2048 -smp 2 -net none /root/rhel6u4.qcow
-incoming tcp:localhost:4444
3. ctrl+alt+2 to change to qemu monitor
4. migrate tcp:localhost:4444


Current result:
----------------
guest hang, and print "KVM: entry failed, hardware error 0x80000021"

Expected result:
----------------
after live/migration or save/restore, the guest works fine

Basic root-causing log:
----------------------
after live/migration or save/restore, the command line will print:

KVM: entry failed, hardware error 0x80000021

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=00000000
ESI=00000001 EDI=81de1228 EBP=81a01ec8 ESP=81a01ec8
EIP=8103b90b EFL=00000246 [---Z-P-] CPL=0 II=0 A20=1 SMM=0 HLT=0
ES =0000 00000000 0000ffff 00009300
CS =f000 ffff0000 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
Code=00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 <00> 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

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[Bug 63121] The guest will hang after live migration.

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=63121

--- Comment #1 from Zhou, Chao <chao.zhou@intel.com> ---
the first bad commit is: 
commit d7876f1be40a16223a44355740de625849504eb5
Author: Paolo Bonzini <pbonzini@redhat.com>
Date:   Wed Oct 2 16:06:15 2013 +0200

    KVM: x86: prevent setting unsupported XSAVE states

    A guest can still attempt to save and restore XSAVE states even if they
    have been masked in CPUID leaf 0Dh.  This usually is not visible to
    the guest, but is still wrong: "Any attempt to set a reserved bit (as
    determined by the contents of EAX and EDX after executing CPUID with
    EAX=0DH, ECX= 0H) in XCR0 for a given processor will result in a #GP
    exception".

    The patch also performs the same checks as __kvm_set_xcr in KVM_SET_XSAVE.
    This catches migration from newer to older kernel/processor before the
    guest starts running.

    Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
    Signed-off-by: Gleb Natapov <gleb@redhat.com>

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[Bug 63121] The guest will hang after live migration.

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=63121

Paolo Bonzini <bonzini@gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bonzini@gnu.org

--- Comment #2 from Paolo Bonzini <bonzini@gnu.org> ---
Reproduced on Ivy Bridge host with "-cpu Westmere", passes with "-cpu
SandyBridge".

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[Bug 63121] The guest will hang after live migration.

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=63121

Zhou, Chao <chao.zhou@intel.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |CODE_FIX

--- Comment #3 from Zhou, Chao <chao.zhou@intel.com> ---
this commit fixed the bug:
commit 46c34cb059d519601fb567b55cf45c300fea2928
Author: Paolo Bonzini <pbonzini@redhat.com>
Date:   Thu Oct 17 16:50:46 2013 +0200

    KVM: x86: fix KVM_SET_XCRS for CPUs that do not support XSAVE

    The KVM_SET_XCRS ioctl must accept anything that KVM_GET_XCRS
    could return.  XCR0's bit 0 is always 1 in real processors with
    XSAVE, and KVM_GET_XCRS will always leave bit 0 set even if the
    emulated processor does not have XSAVE.  So, KVM_SET_XCRS must
    ignore that bit when checking for attempts to enable unsupported
    save states.

    Reviewed-by: Gleb Natapov <gleb@redhat.com>
    Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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[Bug 63121] The guest will hang after live migration.

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=63121

Zhou, Chao <chao.zhou@intel.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |VERIFIED

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