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

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Message-ID: <aLCwVwjWe07Ievno@casper.infradead.org>
Date: Thu, 28 Aug 2025 20:39:03 +0100
From: Matthew Wilcox <willy@...radead.org>
To: Dave Hansen <dave.hansen@...el.com>
Cc: Jason Gunthorpe <jgg@...dia.com>, "Tian, Kevin" <kevin.tian@...el.com>,
	Baolu Lu <baolu.lu@...ux.intel.com>, Joerg Roedel <joro@...tes.org>,
	Will Deacon <will@...nel.org>, Robin Murphy <robin.murphy@....com>,
	Jann Horn <jannh@...gle.com>, Vasant Hegde <vasant.hegde@....com>,
	Alistair Popple <apopple@...dia.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Uladzislau Rezki <urezki@...il.com>,
	Jean-Philippe Brucker <jean-philippe@...aro.org>,
	Andy Lutomirski <luto@...nel.org>, "Lai, Yi1" <yi1.lai@...el.com>,
	"iommu@...ts.linux.dev" <iommu@...ts.linux.dev>,
	"security@...nel.org" <security@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"stable@...r.kernel.org" <stable@...r.kernel.org>,
	"vishal.moola@...il.com" <vishal.moola@...il.com>
Subject: Re: [PATCH v3 1/1] iommu/sva: Invalidate KVA range on kernel TLB
 flush

On Thu, Aug 28, 2025 at 12:31:40PM -0700, Dave Hansen wrote:
> 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.

There's a bunch of "Ideally" in ptdesc, but I'm equially too lazy to do
that before I've proven everything works great with slab and/or folios.
It'll have to be changed no matter which way we do it, so as long as
it's obvious where needs to be changed, it's fine.  I deem this
"good enough for now".