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

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Message-ID: <20250708140629.GQ904431@ziepe.ca>
Date: Tue, 8 Jul 2025 11:06:29 -0300
From: Jason Gunthorpe <jgg@...pe.ca>
To: Baolu Lu <baolu.lu@...ux.intel.com>
Cc: Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
	Robin Murphy <robin.murphy@....com>,
	Kevin Tian <kevin.tian@...el.com>, Jann Horn <jannh@...gle.com>,
	Vasant Hegde <vasant.hegde@....com>,
	Dave Hansen <dave.hansen@...el.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>, Yi Lai <yi1.lai@...el.com>,
	iommu@...ts.linux.dev, security@...nel.org,
	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH 1/1] iommu/sva: Invalidate KVA range on kernel TLB flush

On Tue, Jul 08, 2025 at 09:27:55AM -0300, Jason Gunthorpe wrote:
> On Tue, Jul 08, 2025 at 01:42:53PM +0800, Baolu Lu wrote:
> > > +void iommu_sva_invalidate_kva_range(unsigned long start, unsigned long end)
> > > +{
> > > +	struct iommu_mm_data *iommu_mm;
> > > +
> > > +	might_sleep();
> > 
> > Yi Lai <yi1.lai@...el.com> reported an issue here. This interface could
> > potentially be called in a non-sleepable context.
> 
> Oh thats really bad, the notifiers inside the iommu driver are not
> required to be called in a sleepable context either and I don't really
> want to change that requirement.

Actually, I have got confused here with the hmm use of notifiers.

The iommu drivers use arch_invalidate_secondary_tlbs so they are
already in atomic contexts.

So your idea to use a spinlock seems correct.

Jason