Re: [PATCH] iommu/dma: Fix domain init

[Robin Murphy]

On 21/05/2024 5:45 am, Jerry Snitselaar wrote:
> On Mon, May 20, 2024 at 08:14:44PM GMT, Robin Murphy wrote:
> > Despite carefully rewording the kerneldoc to describe the new direct
> > interaction with dma_range_map, it seems I managed to confuse myself in
> > removing the redundant force_aperture check and ended up making the code
> > not do that at all. This led to dma_range_maps inadvertently being able
> > to set iovad->start_pfn = 0, and all the nonsensical chaos which ensues
> > from there. Restore the correct behaviour of constraining base_pfn to
> > the domain aperture regardless of dma_range_map, and not trying to apply
> > dma_range_map constraints to the basic IOVA domain since they will be
> > properly handled with reserved regions later.
> >
> > Reported-by: Jon Hunter <jonathanh@xxxxxxxxxx>
> > Reported-by: Jerry Snitselaar <jsnitsel@xxxxxxxxxx>
> > Fixes: e28a114243d1 ("iommu/dma: Make limit checks self-contained")
>
> I'm seeing this upstream as ad4750b07d34 ("iommu/dma: Make limit checks self-contained") now.

What, you mean when Linus pulls some patches I wrote he *doesn't* also 
rebase my local development branch for me? /facepalm

Joerg, please shout if you'd like a resend for that.

> > Signed-off-by: Robin Murphy <robin.murphy@xxxxxxx>
> > ---
>
> Tested-by: Jerry Snitselaar <jsnitsel@xxxxxxxxxx>
> Reviewed-by: Jerry Snitselaar <jsnitsel@xxxxxxxxxx>

Thanks!
Robin.

> >   drivers/iommu/dma-iommu.c | 8 ++++----
> >   1 file changed, 4 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
> > index 89a53c2f2cf9..1ec89ca75c59 100644
> > --- a/drivers/iommu/dma-iommu.c
> > +++ b/drivers/iommu/dma-iommu.c
> > @@ -685,15 +685,15 @@ static int iommu_dma_init_domain(struct iommu_domain *domain, struct device *dev
> >   
> >   	/* Check the domain allows at least some access to the device... */
> >   	if (map) {
> > -		dma_addr_t base = dma_range_map_min(map);
> > -		if (base > domain->geometry.aperture_end ||
> > +		if (dma_range_map_min(map) > domain->geometry.aperture_end ||
> >   		    dma_range_map_max(map) < domain->geometry.aperture_start) {
> >   			pr_warn("specified DMA range outside IOMMU capability\n");
> >   			return -EFAULT;
> >   		}
> > -		/* ...then finally give it a kicking to make sure it fits */
> > -		base_pfn = max(base, domain->geometry.aperture_start) >> order;
> >   	}
> > +	/* ...then finally give it a kicking to make sure it fits */
> > +	base_pfn = max_t(unsigned long, base_pfn,
> > +			 domain->geometry.aperture_start >> order);
> >   
> >   	/* start_pfn is always nonzero for an already-initialised domain */
> >   	mutex_lock(&cookie->mutex);
> > --
> > 2.39.2.101.g768bb238c484.dirty