Re: [PATCH v3 08/24] iommu/io-pgtable-arm-v7s: Use ias to check the valid iova in unmap

Yong Wu
2020-10-26T07:51:16Z

On Fri, 2020-10-23 at 12:17 +0100, Will Deacon wrote:
> On Wed, Sep 30, 2020 at 03:06:31PM +0800, Yong Wu wrote:
> > Use the ias for the valid iova checking in arm_v7s_unmap. This is a
> > preparing patch for supporting iova 34bit for MediaTek.
> > BTW, change the ias/oas checking format in arm_v7s_map.
> >
> > Signed-off-by: Yong Wu <yong.wu@mediatek.com>
> > ---
> > drivers/iommu/io-pgtable-arm-v7s.c | 5 ++---
> > 1 file changed, 2 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/iommu/io-pgtable-arm-v7s.c b/drivers/iommu/io-pgtable-arm-v7s.c
> > index a688f22cbe3b..4c9d8dccfc5a 100644
> > --- a/drivers/iommu/io-pgtable-arm-v7s.c
> > +++ b/drivers/iommu/io-pgtable-arm-v7s.c
> > @@ -526,8 +526,7 @@ static int arm_v7s_map(struct io_pgtable_ops *ops, unsigned long iova,
> > if (!(prot & (IOMMU_READ | IOMMU_WRITE)))
> > return 0;
> >
> > - if (WARN_ON(iova >= (1ULL << data->iop.cfg.ias) ||
> > - paddr >= (1ULL << data->iop.cfg.oas)))
> > + if (WARN_ON(iova >> data->iop.cfg.ias || paddr >> data->iop.cfg.oas))
> > return -ERANGE;
>
> As discussed when reviewing these for Android, please leave this code as-is.
>
> >
> > ret = __arm_v7s_map(data, iova, paddr, size, prot, 1, data->pgd, gfp);
> > @@ -717,7 +716,7 @@ static size_t arm_v7s_unmap(struct io_pgtable_ops *ops, unsigned long iova,
> > {
> > struct arm_v7s_io_pgtable *data = io_pgtable_ops_to_data(ops);
> >
> > - if (WARN_ON(upper_32_bits(iova)))
> > + if (WARN_ON(iova >> data->iop.cfg.ias))
> > return 0;
>
> And avoid the UB here for 32-bit machines by comparing with 1ULL <<
> iop.cfg.ias instead.

Thanks. I will fix it in next version.

>
> Thanks,
>
> Will