Re: [KVM PATCH v8 3/3] KVM: add iosignalfd support

Gregory Haskins
2009-06-23T11:40:50Z

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Michael S. Tsirkin wrote:
> On Tue, Jun 23, 2009 at 07:33:07AM -0400, Gregory Haskins wrote:
>
>> Michael S. Tsirkin wrote:
>>
>>> On Thu, Jun 18, 2009 at 08:30:46PM -0400, Gregory Haskins wrote:
>>>
>>>
>>>> +static int
>>>> +iosignalfd_group_in_range(struct kvm_io_device *this, gpa_t addr, int len,
>>>> + int is_write)
>>>> +{
>>>> + struct _iosignalfd_group *p = to_group(this);
>>>> +
>>>> + return ((addr >= p->addr && (addr < p->addr + p->length)));
>>>> +}
>>>>
>>>>
>>> I think I see a problem here. For virtio, we do not necessarily want all
>>> virtqueues for a device to live in kernel: there might be control
>>> virtqueues that we want to leave in userspace. Since this claims all
>>> writes to a specific address, the signal never makes it to userspace.
>>>
>>>
>>>
>> You can use a wildcard. Would that work?
>>
>>
>
> Nope, you need to know the value written.
>
>
Note: You can also terminate an eventfd in userspace...it doesn't have
to terminate in-kernel. Not sure if that helps.

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