Re: KVM Test result, kernel 81e4400.., userspace 08385e4.. , One new issue

[Avi Kivity <avi@qumranet.com>]

Alexander Graf wrote:
>
> On Feb 25, 2008, at 10:34 AM, Avi Kivity wrote:
>
>> Yang, Sheng wrote:
>>> On Monday 25 February 2008 16:41:25 Zhao, Yunfeng wrote:
>>>
>>>> Hi, all,
>>>>
>>>> This is today's KVM test result against kvm.git
>>>> 81e4400b4df4e597a81c19c1161aa03c73613710 and kvm-userspace.git
>>>> 08385e49dcff3585f597870af67301d7659a1ecb.
>>>>
>>>> One new issue has been found in today's testing:
>>>> 1. fc5/fc6/rhel5u1 no-acpi up guests can't boot on pae host
>>>> https://sourceforge.net/tracker/index.php?func=detail&aid=1901208&group_ 
>>>>
>>>> id=180599&atid=893831
>>>>
>>>
>>> A quick bisect shows that the problem caused by "kvm: qemu: fix 
>>> host_cpuid()
>>> on x86_64".
>>>
>>
>> Yeah, I just found this out the hard way (by trying to debug this --
>> silly me).  The effects were that the "GenuineIntel" in cpuid
>> identification was corrupted.
>
> Could you please execute this source on a computer that fails with the 
> argument "0" (please compile with the same switches as qemu) and give 
> me the results + disassembly?


0000101c <host_cpuid>:
    101c:       55                      push   %ebp
    101d:       89 e5                   mov    %esp,%ebp
    101f:       57                      push   %edi
    1020:       56                      push   %esi
    1021:       53                      push   %ebx
    1022:       83 ec 3c                sub    $0x3c,%esp
    1025:       89 55 d4                mov    %edx,-0x2c(%ebp)
    1028:       89 de                   mov    %ebx,%esi
    102a:       0f a2                   cpuid
    102c:       89 db                   mov    %ebx,%ebx
    102e:       89 f3                   mov    %esi,%ebx
    1030:       89 d7                   mov    %edx,%edi
    1032:       89 55 e4                mov    %edx,-0x1c(%ebp)
    1035:       8b 55 d4                mov    -0x2c(%ebp),%edx
    1038:       85 d2                   test   %edx,%edx
    103a:       89 4d c4                mov    %ecx,-0x3c(%ebp)
    103d:       89 5d d0                mov    %ebx,-0x30(%ebp)
    1040:       89 45 d8                mov    %eax,-0x28(%ebp)
    1043:       89 5d dc                mov    %ebx,-0x24(%ebp)
    1046:       89 4d e0                mov    %ecx,-0x20(%ebp)
    1049:       74 05                   je     1050 <host_cpuid+0x34>
    104b:       8b 55 d4                mov    -0x2c(%ebp),%edx
    104e:       89 02                   mov    %eax,(%edx)
    1050:       8b 75 08                mov    0x8(%ebp),%esi
    1053:       85 f6                   test   %esi,%esi
    1055:       74 08                   je     105f <host_cpuid+0x43>
    1057:       8b 5d d0                mov    -0x30(%ebp),%ebx
    105a:       8b 4d 08                mov    0x8(%ebp),%ecx
    105d:       89 19                   mov    %ebx,(%ecx)
    105f:       8b 5d 0c                mov    0xc(%ebp),%ebx
    1062:       85 db                   test   %ebx,%ebx
    1064:       74 08                   je     106e <host_cpuid+0x52>
    1066:       8b 55 c4                mov    -0x3c(%ebp),%edx
    1069:       8b 45 0c                mov    0xc(%ebp),%eax
    106c:       89 10                   mov    %edx,(%eax)
    106e:       8b 4d 10                mov    0x10(%ebp),%ecx
    1071:       85 c9                   test   %ecx,%ecx
    1073:       74 05                   je     107a <host_cpuid+0x5e>
    1075:       8b 4d 10                mov    0x10(%ebp),%ecx
    1078:       89 39                   mov    %edi,(%ecx)
    107a:       83 c4 3c                add    $0x3c,%esp
    107d:       5b                      pop    %ebx
    107e:       5e                      pop    %esi
    107f:       5f                      pop    %edi
    1080:       c9                      leave
    1081:       c3                      ret


Looks like %ebx was chosen for %1.  I also don't see where %eax is loaded.

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.


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