[PATCH v5 01/27] iommu/arm-smmu-v3: Do not allow a SVA domain to be set on the wrong PASID

[Mostafa Saleh]

On Tue, Mar 26, 2024 at 03:30:16PM -0300, Jason Gunthorpe wrote:
> On Fri, Mar 22, 2024 at 05:48:52PM +0000, Mostafa Saleh wrote:
> > Hi Jason,
> > 
> > On Mon, Mar 04, 2024 at 07:43:49PM -0400, Jason Gunthorpe wrote:
> > > The SVA code is wired to assume that the SVA is programmed onto the
> > > mm->pasid. The current core code always does this, so it is fine.
> > > 
> > > Add a check for clarity.
> > > 
> > > Tested-by: Nicolin Chen <nicolinc at nvidia.com>
> > > Signed-off-by: Jason Gunthorpe <jgg at nvidia.com>
> > > ---
> > >  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c | 3 +++
> > >  1 file changed, 3 insertions(+)
> > > 
> > > diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
> > > index 2610e82c0ecd0d..347c2fdd865c1a 100644
> > > --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
> > > +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
> > > @@ -581,6 +581,9 @@ static int arm_smmu_sva_set_dev_pasid(struct iommu_domain *domain,
> > >  	int ret = 0;
> > >  	struct mm_struct *mm = domain->mm;
> > >  
> > > +	if (mm_get_enqcmd_pasid(mm) != id)
> > > +		return -EINVAL;
> > > +
> > I am not sure if that is needed, the only caller in the tree is the IOMMU code
> > and it does the right thing, as that check is removed later anyway, I don’t
> > think this patch adds much.
> 
> It really should be backported, when we get drivers that do other
> things it creates a hazard. I've added a fixes line.

Maybe I am misunderstanding the case, but AFAIU, the only caller for this is
iommu_sva_bind_device() which is the function populating the pasid, so this
condition should never hit with the current code.
And Linux won’t backport new drivers, so there is no need to do that?

Thanks,
Mostafa