On Wed, Jun 28, 2023 at 10:00:56AM +0800, Baolu Lu wrote:
> > If the driver created a SVA domain then the op should point to some
> > generic 'handle sva fault' function. There shouldn't be weird SVA
> > stuff in the core code.
> >
> > The weird SVA stuff is really just a generic per-device workqueue
> > dispatcher, so if we think that is valuable then it should be
> > integrated into the iommu_domain (domain->ops->use_iopf_workqueue =
> > true for instance). Then it could route the fault through the
> > workqueue and still invoke domain->ops->iopf_handler.
> >
> > The word "SVA" should not appear in any of this.
>
> Yes. We should make it generic. The domain->use_iopf_workqueue flag
> denotes that the page faults of a fault group should be put together and
> then be handled and responded in a workqueue. Otherwise, the page fault
> is dispatched to domain->iopf_handler directly.
It might be better to have iopf_handler and
iopf_handler_work function pointers to distinguish to two cases.
> > Not sure what iommu_register_device_fault_handler() has to do with all
> > of this.. Setting up the dev_iommu stuff to allow for the workqueue
> > should happen dynamically during domain attach, ideally in the core
> > code before calling to the driver.
>
> There are two pointers under struct dev_iommu for fault handling.
>
> /**
> * struct dev_iommu - Collection of per-device IOMMU data
> *
> * @fault_param: IOMMU detected device fault reporting data
> * @iopf_param: I/O Page Fault queue and data
>
> [...]
>
> struct dev_iommu {
> struct mutex lock;
> struct iommu_fault_param *fault_param;
> struct iopf_device_param *iopf_param;
>
> My understanding is that @fault_param is a place holder for generic
> things, while @iopf_param is workqueue specific.
Well, lets look
struct iommu_fault_param {
iommu_dev_fault_handler_t handler;
void *data;
These two make no sense now. handler is always iommu_queue_iopf. Given
our domain centric design we want the function pointer in the domain,
not in the device. So delete it.
struct list_head faults;
struct mutex lock;
Queue of unhandled/unacked faults? Seems sort of reasonable
> @iopf_param could be allocated on demand. (perhaps renaming it to a more
> meaningful one?) It happens before a domain with use_iopf_workqueue flag
> set attaches to a device. iopf_param keeps alive until device_release.
Yes
Do this for the iommu_fault_param as well, in fact, probably just put
the two things together in one allocation and allocate if we attach a
PRI using domain. I don't think we need to micro optimze further..
Jason
_______________________________________________
Virtualization mailing list
Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
https://lists.linuxfoundation.org/mailman/listinfo/virtualization
