linux-kernel - Re: [PATCH v7 1/4] iommu/io-pgtable-arm: Make pgtable walker more generic

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Message-ID: <CAF6AEGtkwjs4XLEBpo2O7W+UgbdxGoMAsYd+3Cr_qY88ofpMjQ@mail.gmail.com>
Date: Fri, 23 Aug 2024 10:23:25 -0700
From: Rob Clark <robdclark@...il.com>
To: Will Deacon <will@...nel.org>
Cc: iommu@...ts.linux.dev, linux-arm-msm@...r.kernel.org, 
	freedreno@...ts.freedesktop.org, Mostafa Saleh <smostafa@...gle.com>, 
	Rob Clark <robdclark@...omium.org>, Robin Murphy <robin.murphy@....com>, 
	Joerg Roedel <joro@...tes.org>, 
	"moderated list:ARM SMMU DRIVERS" <linux-arm-kernel@...ts.infradead.org>, 
	open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v7 1/4] iommu/io-pgtable-arm: Make pgtable walker more generic

On Fri, Aug 23, 2024 at 9:09 AM Will Deacon <will@...nel.org> wrote:
>
> On Tue, Aug 20, 2024 at 10:16:44AM -0700, Rob Clark wrote:
> > diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
> > index f5d9fd1f45bf..b4bc358740e0 100644
> > --- a/drivers/iommu/io-pgtable-arm.c
> > +++ b/drivers/iommu/io-pgtable-arm.c
> > @@ -747,33 +747,31 @@ static phys_addr_t arm_lpae_iova_to_phys(struct io_pgtable_ops *ops,
> >  }
> >
> >  struct io_pgtable_walk_data {
> > -     struct iommu_dirty_bitmap       *dirty;
> > +     void                            *data;
> > +     int (*visit)(struct io_pgtable_walk_data *walk_data, int lvl,
> > +                  arm_lpae_iopte pte, size_t size);
> >       unsigned long                   flags;
> >       u64                             addr;
> >       const u64                       end;
> >  };
> >
> > -static int __arm_lpae_iopte_walk_dirty(struct arm_lpae_io_pgtable *data,
> > -                                    struct io_pgtable_walk_data *walk_data,
> > -                                    arm_lpae_iopte *ptep,
> > -                                    int lvl);
> > +static int __arm_lpae_iopte_walk(struct arm_lpae_io_pgtable *data,
> > +                              struct io_pgtable_walk_data *walk_data,
> > +                              arm_lpae_iopte *ptep,
> > +                              int lvl);
> >
> > -static int io_pgtable_visit_dirty(struct arm_lpae_io_pgtable *data,
> > -                               struct io_pgtable_walk_data *walk_data,
> > -                               arm_lpae_iopte *ptep, int lvl)
> > +static int io_pgtable_visit(struct arm_lpae_io_pgtable *data,
> > +                         struct io_pgtable_walk_data *walk_data,
> > +                         arm_lpae_iopte *ptep, int lvl)
> >  {
> >       struct io_pgtable *iop = &data->iop;
> >       arm_lpae_iopte pte = READ_ONCE(*ptep);
> >
> >       if (iopte_leaf(pte, lvl, iop->fmt)) {
> >               size_t size = ARM_LPAE_BLOCK_SIZE(lvl, data);
> > -
> > -             if (iopte_writeable_dirty(pte)) {
> > -                     iommu_dirty_bitmap_record(walk_data->dirty,
> > -                                               walk_data->addr, size);
> > -                     if (!(walk_data->flags & IOMMU_DIRTY_NO_CLEAR))
> > -                             iopte_set_writeable_clean(ptep);
> > -             }
> > +             int ret = walk_data->visit(walk_data, lvl, pte, size);
> > +             if (ret)
> > +                     return ret;
> >               walk_data->addr += size;
> >               return 0;
> >       }
> > @@ -782,13 +780,13 @@ static int io_pgtable_visit_dirty(struct arm_lpae_io_pgtable *data,
> >               return -EINVAL;
> >
> >       ptep = iopte_deref(pte, data);
> > -     return __arm_lpae_iopte_walk_dirty(data, walk_data, ptep, lvl + 1);
> > +     return __arm_lpae_iopte_walk(data, walk_data, ptep, lvl + 1);
> >  }
> >
> > -static int __arm_lpae_iopte_walk_dirty(struct arm_lpae_io_pgtable *data,
> > -                                    struct io_pgtable_walk_data *walk_data,
> > -                                    arm_lpae_iopte *ptep,
> > -                                    int lvl)
> > +static int __arm_lpae_iopte_walk(struct arm_lpae_io_pgtable *data,
> > +                              struct io_pgtable_walk_data *walk_data,
> > +                              arm_lpae_iopte *ptep,
> > +                              int lvl)
> >  {
> >       u32 idx;
> >       int max_entries, ret;
> > @@ -803,7 +801,7 @@ static int __arm_lpae_iopte_walk_dirty(struct arm_lpae_io_pgtable *data,
> >
> >       for (idx = ARM_LPAE_LVL_IDX(walk_data->addr, lvl, data);
> >            (idx < max_entries) && (walk_data->addr < walk_data->end); ++idx) {
> > -             ret = io_pgtable_visit_dirty(data, walk_data, ptep + idx, lvl);
> > +             ret = io_pgtable_visit(data, walk_data, ptep + idx, lvl);
> >               if (ret)
> >                       return ret;
> >       }
> > @@ -811,6 +809,20 @@ static int __arm_lpae_iopte_walk_dirty(struct arm_lpae_io_pgtable *data,
> >       return 0;
> >  }
> >
> > +static int visit_dirty(struct io_pgtable_walk_data *walk_data, int lvl,
> > +                    arm_lpae_iopte pte, size_t size)
> > +{
> > +     struct iommu_dirty_bitmap *dirty = walk_data->data;
> > +
> > +     if (iopte_writeable_dirty(pte)) {
> > +             iommu_dirty_bitmap_record(dirty, walk_data->addr, size);
> > +             if (!(walk_data->flags & IOMMU_DIRTY_NO_CLEAR))
> > +                     iopte_set_writeable_clean(&pte);
>
> Are you sure that's correct? I suspect we really want to update the actual
> page-table in this case, so we probably want to pass the pointer in instead
> of the pte value.

oh, right

> Will