linux-kernel - Re: [PATCH 06/21] iommu/io-pgtable-arm-v7s: Use ias to check the valid iova in unmap

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Date:   Mon, 13 Jul 2020 08:38:24 +0800
From:   Nicolas Boichat <drinkcat@...omium.org>
To:     Yong Wu <yong.wu@...iatek.com>
Cc:     Joerg Roedel <joro@...tes.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Will Deacon <will@...nel.org>,
        Evan Green <evgreen@...omium.org>,
        Tomasz Figa <tfiga@...gle.com>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@...ts.infradead.org>,
        srv_heupstream <srv_heupstream@...iatek.com>,
        Devicetree List <devicetree@...r.kernel.org>,
        lkml <linux-kernel@...r.kernel.org>,
        linux-arm Mailing List <linux-arm-kernel@...ts.infradead.org>,
        iommu@...ts.linux-foundation.org, youlin.pei@...iatek.com,
        anan.sun@...iatek.com, cui.zhang@...iatek.com,
        chao.hao@...iatek.com, ming-fan.chen@...iatek.com
Subject: Re: [PATCH 06/21] iommu/io-pgtable-arm-v7s: Use ias to check the
 valid iova in unmap

On Sat, Jul 11, 2020 at 2:50 PM Yong Wu <yong.wu@...iatek.com> wrote:
>
> As title.
>
> Signed-off-by: Yong Wu <yong.wu@...iatek.com>
> ---
>  drivers/iommu/io-pgtable-arm-v7s.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/iommu/io-pgtable-arm-v7s.c b/drivers/iommu/io-pgtable-arm-v7s.c
> index 4272fe4e17f4..01f2a8876808 100644
> --- a/drivers/iommu/io-pgtable-arm-v7s.c
> +++ b/drivers/iommu/io-pgtable-arm-v7s.c
> @@ -717,7 +717,7 @@ 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 >= (1ULL << data->iop.cfg.ias)))

This is a little odd as iova is unsigned long and 1ULL is unsigned long long.

Would it be better to keep the spirit of the previous test and do
something like:
 if (WARN_ON(iova >> data->iop.cfg.ias)) ?

>                 return 0;
>
>         return __arm_v7s_unmap(data, gather, iova, size, 1, data->pgd);
> --
> 2.18.0