On Mon, Oct 23, 2023 at 10:59:35AM -0300, Jason Gunthorpe wrote:
On Sun, Oct 22, 2023 at 05:18:03PM -0700, Nicolin Chen wrote:
And where should we add this comment? Kdoc of the alloc uAPI?
Maybe right in front of the only enforce_cc op callback?
OK. How about this? Might be a bit verbose though: /* * enforce_cache_coherenc must be determined during the HWPT allocation. * Note that a HWPT (non-CC) created for a device (non-CC) can be later * reused by another device (either non-CC or CC). However, A HWPT (CC) * created for a device (CC) cannot be reused by another device (non-CC) * but only devices (CC). Instead user space in this case would need to * allocate a separate HWPT (non-CC). */
Ok, fix the spello in enforce_cache_coherenc
Oops.
I also found the existing piece sorta says a similar thing: * Set the coherency mode before we do iopt_table_add_domain() as some * iommus have a per-PTE bit that controls it and need to decide before * doing any maps.
So, did this and sending v3: - * enforce_cache_coherenc must be determined during the HWPT allocation. + * The cache coherency mode must be configured here and unchanged later.