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Re: [Qemu-devel] [PATCH 0/2 v3] kvm: notify host when guest panicked
From: |
Jan Kiszka |
Subject: |
Re: [Qemu-devel] [PATCH 0/2 v3] kvm: notify host when guest panicked |
Date: |
Thu, 15 Mar 2012 12:25:35 +0100 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 |
On 2012-03-15 11:39, Gleb Natapov wrote:
> On Wed, Mar 14, 2012 at 11:46:08AM -0700, Eric Northup wrote:
>> On Wed, Mar 14, 2012 at 6:25 AM, Gleb Natapov <address@hidden> 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.
>>
> There was such vm exit (KVM_EXIT_HYPERCALL), but it was deemed to be a
> bad idea.
BTW, this would help a lot in emulating hypercalls of other hypervisors
(or of KVM's VAPIC in the absence of in-kernel irqchip - I had to jump
through hoops therefore) in user space. Not all those hypercall handlers
actually have to reside in the KVM module.
Jan
--
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux
- Re: [Qemu-devel] [PATCH 0/2 v3] kvm: notify host when guest panicked, (continued)
- Re: [Qemu-devel] [PATCH 0/2 v3] kvm: notify host when guest panicked, Avi Kivity, 2012/03/14
- Re: [Qemu-devel] [PATCH 0/2 v3] kvm: notify host when guest panicked, Wen Congyang, 2012/03/14
- Re: [Qemu-devel] [PATCH 0/2 v3] kvm: notify host when guest panicked, Avi Kivity, 2012/03/14
- Re: [Qemu-devel] [PATCH 0/2 v3] kvm: notify host when guest panicked, Avi Kivity, 2012/03/14
- Re: [Qemu-devel] [PATCH 0/2 v3] kvm: notify host when guest panicked, Gleb Natapov, 2012/03/14
- Re: [Qemu-devel] [PATCH 0/2 v3] kvm: notify host when guest panicked, Avi Kivity, 2012/03/14
- Re: [Qemu-devel] [PATCH 0/2 v3] kvm: notify host when guest panicked, Gleb Natapov, 2012/03/14
- Re: [Qemu-devel] [PATCH 0/2 v3] kvm: notify host when guest panicked, Eric Northup, 2012/03/14
- Re: [Qemu-devel] [PATCH 0/2 v3] kvm: notify host when guest panicked, Wen Congyang, 2012/03/15
- Re: [Qemu-devel] [PATCH 0/2 v3] kvm: notify host when guest panicked, Gleb Natapov, 2012/03/15
- Re: [Qemu-devel] [PATCH 0/2 v3] kvm: notify host when guest panicked,
Jan Kiszka <=
- Re: [Qemu-devel] [PATCH 0/2 v3] kvm: notify host when guest panicked, Avi Kivity, 2012/03/15
- Re: [Qemu-devel] [PATCH 0/2 v3] kvm: notify host when guest panicked, Wen Congyang, 2012/03/16
- Re: [Qemu-devel] [PATCH 0/2 v3] kvm: notify host when guest panicked, Anthony Liguori, 2012/03/21
- Re: [Qemu-devel] [PATCH 0/2 v3] kvm: notify host when guest panicked, Wen Congyang, 2012/03/22
- Re: [Qemu-devel] [PATCH 0/2 v3] kvm: notify host when guest panicked, Eric Northup, 2012/03/14
- Re: [Qemu-devel] [PATCH 0/2 v3] kvm: notify host when guest panicked, Amit Shah, 2012/03/14
- Re: [Qemu-devel] [PATCH 0/2 v3] kvm: notify host when guest panicked, Wen Congyang, 2012/03/14
- Re: [Qemu-devel] [PATCH 0/2 v3] kvm: notify host when guest panicked, Gleb Natapov, 2012/03/14
- Re: [Qemu-devel] [PATCH 0/2 v3] kvm: notify host when guest panicked, Wen Congyang, 2012/03/14
- Re: [Qemu-devel] [PATCH 0/2 v3] kvm: notify host when guest panicked, Gleb Natapov, 2012/03/14