[Qemu-devel] Re: [PATCH 4/4] KVM: Rework of guest debug state writing

[Jan Kiszka]

Marcelo Tosatti wrote:
> On Thu, Feb 04, 2010 at 01:33:50AM +0100, Jan Kiszka wrote:
>> Marcelo Tosatti wrote:
>>> On Wed, Feb 03, 2010 at 10:29:45PM +0100, Jan Kiszka wrote:
>>>> So far we synchronized any dirty VCPU state back into the kernel before
>>>> updating the guest debug state. This was a tribute to a deficit in x86
>>>> kernels before 2.6.33. But as this is an arch-dependent issue, it is
>>>> better handle in the x86 part of KVM and remove the writeback point for
>>>> generic code.
>>> Jan,
>>>
>>> This patch breaks migration.
>> Can you elaborate what you did? I can't reproduce, and I do not see any
>> conceptual issue (given that guest debugging conflicts with migration
>> anyway).
> 
> kvm-autotest fails (migration only, install is ok, both Linux and Win
> guests). Not sure why, perhaps the unconditional KVM_SET_GUEST_DEBUG
> corrupts state somehow? 
> 
> Tested with io thread enabled.

That's this default-off thing, so... OK, confirmed, investigating.

Jan

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