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

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Date:   Mon, 26 Oct 2020 15:49:06 +0800
From:   Yong Wu <yong.wu@...iatek.com>
To:     Will Deacon <will@...nel.org>
CC:     Joerg Roedel <joro@...tes.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Evan Green <evgreen@...omium.org>,
        Tomasz Figa <tfiga@...gle.com>,
        <linux-mediatek@...ts.infradead.org>,
        <srv_heupstream@...iatek.com>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <iommu@...ts.linux-foundation.org>, <youlin.pei@...iatek.com>,
        Nicolas Boichat <drinkcat@...omium.org>,
        <anan.sun@...iatek.com>, <chao.hao@...iatek.com>,
        <ming-fan.chen@...iatek.com>,
        Greg Kroah-Hartman <gregkh@...gle.com>,
        <kernel-team@...roid.com>
Subject: Re: [PATCH v3 08/24] iommu/io-pgtable-arm-v7s: Use ias to check the
 valid iova in unmap

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@...iatek.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