Re: [PATCH 3/3] KVM: Enable MSI-X for KVM assigned device

[Avi Kivity <avi@redhat.com>]

Sheng Yang wrote:
>
>>>   struct kvm_assigned_msix_nr {
>>>  	__u32 assigned_dev_id;
>>>  	__u16 entry_nr;
>>> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
>>> index 4010802..d3acb37 100644
>>> --- a/virt/kvm/kvm_main.c
>>> +++ b/virt/kvm/kvm_main.c
>>> @@ -280,13 +280,33 @@ static void kvm_free_assigned_irq(struct kvm *kvm,
>>>  	 * now, the kvm state is still legal for probably we also have to wait
>>>  	 * interrupt_work done.
>>>  	 */
>>> -	disable_irq_nosync(assigned_dev->host_irq);
>>> -	cancel_work_sync(&assigned_dev->interrupt_work);
>>> +	if (assigned_dev->irq_requested_type & KVM_ASSIGNED_DEV_MSIX) {
>>> +		int i;
>>> +		for (i = 0; i < assigned_dev->entries_nr; i++)
>>> +			disable_irq_nosync(assigned_dev->
>>> +					   host_msix_entries[i].vector);
>>> +
>>> +		cancel_work_sync(&assigned_dev->interrupt_work);
>>> +
>>> +		for (i = 0; i < assigned_dev->entries_nr; i++)
>>> +			free_irq(assigned_dev->host_msix_entries[i].vector,
>>> +				 (void *)assigned_dev);
>>> +
>>> +		assigned_dev->entries_nr = 0;
>>> +		kfree(assigned_dev->host_msix_entries);
>>> +		kfree(assigned_dev->guest_msix_entries);
>>> +		pci_disable_msix(assigned_dev->dev);
>>> +	} else {
>>> +		/* Deal with MSI and INTx */
>>> +		disable_irq_nosync(assigned_dev->host_irq);
>>> +		cancel_work_sync(&assigned_dev->interrupt_work);
>>>   
>>>       
>> How about always have an array?  That will also allow us to deal with  
>> INTx where x=B,C,D.
>>
>> Currently for MSI and INTx the array will hold just one active element.
>>     
>
> So array, or bitmap? I remember I changed it to bitmap accounding to your
> first comment...
>   

Which bitmap?  I'm confused.

I'm talking about unifying the existing array 
(assigned_dev->host_msix_entries[]) with ->host_irq.  Also since we need 
an array for INTx when a function uses INT[BCD].

So we'll have assigned_dev->host_irqs[], each entry can be INTx or MSI 
or MSIx.

> OK. I think array is reasonable, but the length is a problem, as I did before. How long would you like?
>   

MAX(4, KVM_MAX_MSIX_ENTRIES), no?

-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.