Re: [PATCH 0/4] Export offsets of VMCS fields as note information for kdump

[Avi Kivity <avi@redhat.com>]

On 04/11/2012 04:39 AM, zhangyanfei wrote:
> This patch set exports offsets of VMCS fields as note information for
> kdump. We call it VMCSINFO. The purpose of VMCSINFO is to retrieve
> runtime state of guest machine image, such as registers, in host
> machine's crash dump as VMCS format. The problem is that VMCS
> internal is hidden by Intel in its specification. So, we reverse
> engineering it in the way implemented in this patch set. Please note
> that this processing never affects any existing kvm logic. The
> VMCSINFO is exported via sysfs to kexec-tools just like VMCOREINFO.
>
> Here is an example:
> Processor: Intel(R) Core(TM)2 Duo CPU     E7500  @ 2.93GHz
>
> $cat /sys/kernel/vmcsinfo
> 1cba8c0 2000
>
> crash> rd -p 1cba8c0 1000
>          1cba8c0:  0000127b00000009 53434d5600000000   ....{.......VMCS
>          1cba8d0:  000000004f464e49 4e4f495349564552   INFO....REVISION
>          1cba8e0:  49460a643d44495f 5f4e495028444c45   _ID=d.FIELD(PIN_
>          1cba8f0:  4d565f4445534142 4f435f434558455f   BASED_VM_EXEC_CO
>          1cba900:  303d294c4f52544e 0a30383130343831   NTROL)=01840180.
>          1cba910:  504328444c454946 5f44455341425f55   FIELD(CPU_BASED_
>          1cba920:  5f434558455f4d56 294c4f52544e4f43   VM_EXEC_CONTROL)
>          1cba930:  393130343931303d 28444c4549460a30   =01940190.FIELD(
>          1cba940:  5241444e4f434553 4558455f4d565f59   SECONDARY_VM_EXE
>          1cba950:  4f52544e4f435f43 30346566303d294c   C_CONTROL)=0fe40
>          1cba960:  4c4549460a306566 4958455f4d562844   fe0.FIELD(VM_EXI
>          1cba970:  4f52544e4f435f54 346531303d29534c   T_CONTROLS)=01e4
>          1cba980:  4549460a30653130 4e455f4d5628444c   01e0.FIELD(VM_EN
>          1cba990:  544e4f435f595254 33303d29534c4f52   TRY_CONTROLS)=03
>          1cba9a0:  460a303133303431 45554728444c4549   140310.FIELD(GUE
>          1cba9b0:  45535f53455f5453 3d29524f5443454c   ST_ES_SELECTOR)=
>          1cba9c0:  4549460a30303530 545345554728444c   0500.FIELD(GUEST
>          1cba9d0:  454c45535f53435f 35303d29524f5443   _CS_SELECTOR)=05
>          ......
>
> TODO:
>   1. In kexec-tools, get VMCSINFO via sysfs and dump it as note information
>      into vmcore.
>   2. Dump VMCS region of each guest vcpu and VMCSINFO into qemu-process
>      core file. To do this, we will modify kernel core dumper, gdb gcore
>      and crash gcore.
>   3. Dump guest image from the qemu-process core file into a vmcore.
>

Taking a step back, can you describe the problem scenario you're fixing
here?

-- 
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