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

From: Avi Kivity
Date: Tue Apr 17 2012 - 03:44:27 EST

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
> ......
> 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

error compiling committee.c: too many arguments to function

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