Re: [PATCH v3 1/1] iommu/sva: Invalidate KVA range on kernel TLB flush

[Dave Hansen <dave.hansen@intel.com>]

On 8/28/25 12:10, Jason Gunthorpe wrote:
>> The biggest single chunk of code is defining ptdesc_*_kernel(). The rest
>> of it is painfully simple.
> Seems not great to be casting ptdesc to folio just to use
> folio_set_referenced(), I'm pretty sure that is no the direction
> things are going in..

Ideally, the ptdesc->__page_flags fields would have their own set of
macros just like folios do, right? Alas, I was too lazy to go to the
trouble of conjuring those up for this single bit.

> I'd set the flag yourself or perhaps use the memory of __page_mapping
> to store a flag (but zero it before freeing).

That was my first inclination as well (actually I was going to use
__page_type since the lower 24 bits are evidently open, but same idea).

Willy pointed me in the direction of PG_referenced on IRC, so I took
that path. But I'm open to doing whatever. It's just three lines of code
that probably end up boiling down to

	bts 0x1, 0x8(%rax)
versus
	bts 0x2, 0x16(%rax)

;)