lkml.org 
[lkml]   [2012]   [Mar]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 0/2 v3] kvm: notify host when guest panicked
At 03/15/2012 02:46 AM, Eric Northup Wrote:
> On Wed, Mar 14, 2012 at 6:25 AM, Gleb Natapov <gleb@redhat.com> wrote:
>
>> On Wed, Mar 14, 2012 at 03:16:05PM +0200, Avi Kivity wrote:
>>> On 03/14/2012 03:14 PM, Gleb Natapov wrote:
>>>> On Wed, Mar 14, 2012 at 03:07:46PM +0200, Avi Kivity wrote:
>>>>> On 03/14/2012 01:11 PM, Wen Congyang wrote:
>>>>>>>
>>>>>>> I don't think we want to use the driver. Instead, have a small
>> piece of
>>>>>>> code that resets the device and pushes out a string (the panic
>> message?)
>>>>>>> without any interrupts etc.
>>>>>>>
>>>>>>> It's still going to be less reliable than a hypercall, I agree.
>>>>>>
>>>>>> Do you still want to use complicated and less reliable way?
>>>>>
>>>>> Are you willing to try it out and see how complicated it really is?
>>>>>
>>>>> While it's more complicated, it's also more flexible. You can
>>>>> communicate the panic message, whether the guest is attempting a
>> kdump
>>>>> and its own recovery or whether it wants the host to do it, etc., you
>>>>> can communicate less severe failures like oopses.
>>>>>
>>>> hypercall can take arguments to achieve the same.
>>>
>>> It has to be designed in advance; and every time we notice something's
>>> missing we have to update the host kernel.
>>>
>>
>> We and in the designed stage now. Not to late to design something flexible
>> :) Panic hypercall can take GPA of a buffer where host puts panic info
>> as a parameter. This buffer can be read by QEMU and passed to management.
>>
>
> If a host kernel change is in the works, I think it might be cleanest to
> have the host kernel export a new kind of VCPU exit for unhandled-by-KVM
> hypercalls. Then usermode can respond to the hypercall as appropriate.
> This would permit adding or changing future hypercalls without host kernel
> changes.
>
> "Guest panic" is almost the definition of not-a-fast-path, and so what's
> the reason to handle it in the host kernel.
>
> Punting to user-space wouldn't be a magic bullet for getting good
> interfaces designed, but in my opinion it is a better place to be doing
> them.
>

Do you mean that: the guest execute vmcall instruction, and the host kernel
exits to userspace. The userspace will deal with the vmexit?

Thanks
Wen Congyang


\
 
 \ /
  Last update: 2012-03-15 08:03    [W:0.168 / U:2.064 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site