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SubjectRe: [PATCH v5 1/2] iommu/io-pgtable-arm-v7s: Add a quirk to allow pgtable PA up to 35bit
Date
On Thu, 2022-05-19 at 14:27 +0800, Miles Chen wrote:
> Hi Yunfei,
>
> > The calling to kmem_cache_alloc for level 2 pgtable allocation may
> > run
> > in atomic context, and it fails sometimes when DMA32 zone runs out
> > of
> > memory.
> >
> > Since Mediatek IOMMU hardware support at most 35bit PA in pgtable,
> > so add a quirk to allow the PA of pgtables support up to bit35.
> >
> > Signed-off-by: Ning Li <ning.li@mediatek.com>
> > Signed-off-by: Yunfei Wang <yf.wang@mediatek.com>
> > ---
> > drivers/iommu/io-pgtable-arm-v7s.c | 56 ++++++++++++++++++++++--
> > ------
> > include/linux/io-pgtable.h | 15 +++++---
> > 2 files changed, 52 insertions(+), 19 deletions(-)
> >
> > diff --git a/drivers/iommu/io-pgtable-arm-v7s.c b/drivers/iommu/io-
> > pgtable-arm-v7s.c
>
> ...snip...
>
> > + gfp_t gfp_l1 = __GFP_ZERO | ARM_V7S_TABLE_GFP_DMA;
> > struct io_pgtable_cfg *cfg = &data->iop.cfg;
> > struct device *dev = cfg->iommu_dev;
> > phys_addr_t phys;
> > @@ -241,9 +251,11 @@ static void *__arm_v7s_alloc_table(int lvl,
> > gfp_t gfp,
> > size_t size = ARM_V7S_TABLE_SIZE(lvl, cfg);
> > void *table = NULL;
> >
> > + if (cfg->quirks & IO_PGTABLE_QUIRK_ARM_MTK_TTBR_EXT)
> > + gfp_l1 = __GFP_ZERO;
>
> __GFP_ZERO is an action modifier, if we do not want
> ARM_V7S_TABLE_GFP_DMA (GFP_DMA/GFP_DMA32), use gfp_l1 = (GFP_KERNEL |
> __GFP_ZERO)
>

Hi Miles,
Thanks for the suggestion, we will update it in the next version.

Thanks,
Yunfei.

> > +
> > if (lvl == 1)
> > - table = (void *)__get_free_pages(
> > - __GFP_ZERO | ARM_V7S_TABLE_GFP_DMA,
> > get_order(size));
> > + table = (void *)__get_free_pages(gfp_l1,
> > get_order(size));
> > else if (lvl == 2)
> > table = kmem_cache_zalloc(data->l2_tables, gfp);
> >

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