Re: [PATCH v6 10/13] vpci/header: reset the command register when adding devices

[Oleksandr Andrushchenko <Oleksandr_Andrushchenko@xxxxxxxx>]

On 07.02.22 17:05, Jan Beulich wrote:
> On 07.02.2022 15:46, Oleksandr Andrushchenko wrote:
>> On 07.02.22 16:31, Jan Beulich wrote:
>>> But: What's still missing here then is the separation of guest and host
>>> views. When we set INTx behind the guest's back, it shouldn't observe the
>>> bit set. Or is this meant to be another (big) TODO?
>> But, patch [PATCH v6 09/13] vpci/header: emulate PCI_COMMAND register for 
>> guests
>> already takes care of it, I mean that it will set/reset INTx for the guest
>> according to MSI/MSI-X. So, if we squash these two patches the whole
>> picture will be seen at once.
> Does it? I did get the impression that the guest would be able to observe
> the bit set even after writing zero to it (while a reason exists that Xen
> wants the bit set).
Yes, you are correct: guest might not see what it wanted to set.
I meant that Xen won't allow resetting INTx if it is not possible
due to MSI/MSI-X

Anyways, I think squashing will be a good idea to have the relevant
functionality in a single change set. Will this work for you?
> Jan
>
Thank you,
Oleksandr