Messages in this thread | | | Date | Thu, 8 Jul 2021 07:36:57 -0700 | From | "Raj, Ashok" <> | Subject | Re: Programming PASID in IMS entries |
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Hi Jason
On Thu, Jul 08, 2021 at 09:08:46AM -0300, Jason Gunthorpe wrote: > On Wed, Jul 07, 2021 at 05:33:35PM -0700, Raj, Ashok wrote: > > On Wed, Jul 07, 2021 at 08:58:22PM -0300, Jason Gunthorpe wrote: > > > On Wed, Jul 07, 2021 at 03:12:16PM -0700, Raj, Ashok wrote: > > > > Hi Thomas > > > > > > > > On Wed, Jul 07, 2021 at 10:50:52AM +0200, Thomas Gleixner wrote: > > > > > Megha, > > > > > > > > > > On Wed, Jul 07 2021 at 09:49, Megha Dey wrote: > > > > > > Per your suggestions during the last meeting, we wanted to confirm the > > > > > > sequence to program the PASID into the IMS entries: > > > > > > > > > > > > 1. Add a PASID member to struct msi_desc (Add as part of a union. Other > > > > > > source-id's such as Jason's vm-id can be added to it) > > > > > > > > > > Yes. Though we also discussed storing the default PASID in struct device > > > > > to begin with which is then copied to the msi_desc entries during > > > > > allocation. > > > > > > > > Using default PASID in struct device will work for sub-devices until the > > > > guest needs to enable ENQCMD support. Since the guest kernel can ask for an > > > > interrupt by specifying something in the descriptor submitted via ENQCMD. > > > > Using the PASID in struct device won't be sufficient. > > > > > > Could you could store a pasid table in the struct device and index it > > > by vector? > > > > Possibly... what ever Thomas things is clean. The device specific driver > > would have this already. So providing some call to get this filled in vs > > storing that in struct device. Someone close at heart to the driver model > > is best to comment :-) > > > > IMS core owns the format of the entries right now vs device specific driver. > > I suppose your use case requiring a vm_id might have a different format. > > So this is yet another one the core needs to learn and adapt? > > All entry format stuff is device specific, it shouldn't be in "core" > code.
Well, this is how it started way back last year.
https://lore.kernel.org/lkml/158751209583.36773.15917761221672315662.stgit@djiang5-desk3.ch.intel.com/
Where the driver functions for mask/unmask/write_msg etc. So the core needs
So the format or layout is device specific, but core can dictate the exact message that needs to be written.
> > It is is the same reason that the IRQ chip driver for IDXD should have > IDXD in the name, it is not a generic "IMS core" thing. > > The question mark is probably the locking model, but if IDXD > guarentees the pasid table doesn't change while the irq is active then > maybe it works out well enough.
I think this must be gauranteed at a min? changing things underneath when the interrupts are unmasked would be bad usage.
> > Associating a void * with the irq is also possibly reasonable, I'm not > sure which path makes the most sense. >
Seems like it..
Cheers, Ashok
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