Re: [patch 21/32] NTB/msi: Convert to msi_on_each_desc()

On Tue, Nov 30, 2021 at 08:48:03PM +0100, Thomas Gleixner wrote:

Logan,

On Tue, Nov 30 2021 at 12:21, Logan Gunthorpe wrote:

quoted

On 2021-11-29 5:29 p.m., Thomas Gleixner wrote:

quoted

I'm way too tired to come up with a proper solution for that, but that
PCI_IRQ_VIRTUAL has to die ASAP.

I'm willing to volunteer a bit of my time to clean this up, but I'd need
a bit more direction on what a proper solution would look like. The MSI
domain code is far from well documented nor is it easy to understand.

Fair enough. I'm struggling with finding time to document that properly.

I've not yet made my mind up what the best way forward for this is, but
I have a few ideas which I want to explore deeper.

I may have lost the plot in all of these patches, but I thought the
direction was moving toward the msi_domain_alloc_irqs() approach IDXD
demo'd here:

https://lore.kernel.org/kvm/162164243591.261970.3439987543338120797.stgit@djiang5-desk3.ch.intel.com/ (local)

I'd expect all the descriptor handling code in drivers/ntb/msi.c to
get wrapped in an irq_chip instead of inserting a single-use callback
to the pci core code's implementation:

void __pci_write_msi_msg(struct msi_desc *entry, struct msi_msg *msg)
{
        if (entry->write_msi_msg)
                entry->write_msi_msg(entry, entry->write_msi_msg_data);

If this doesn't become an irq_chip what other way is there to properly
program the addr/data pair as drivers/ntb/msi.c is doing?

Jason