Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Fri, 23 Oct 2020 12:17:41 +0100
From:   Will Deacon <will@kernel.org>
To:     Yong Wu <yong.wu@mediatek.com>
Cc:     Joerg Roedel <joro@8bytes.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Rob Herring <robh+dt@kernel.org>,
        Robin Murphy <robin.murphy@arm.com>,
        Krzysztof Kozlowski <krzk@kernel.org>,
        Evan Green <evgreen@chromium.org>,
        Tomasz Figa <tfiga@google.com>,
        linux-mediatek@lists.infradead.org, srv_heupstream@mediatek.com,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        iommu@lists.linux-foundation.org, youlin.pei@mediatek.com,
        Nicolas Boichat <drinkcat@chromium.org>, anan.sun@mediatek.com,
        chao.hao@mediatek.com, ming-fan.chen@mediatek.com,
        Greg Kroah-Hartman <gregkh@google.com>, kernel-team@android.com
Subject: Re: [PATCH v3 08/24] iommu/io-pgtable-arm-v7s: Use ias to check the
 valid iova in unmap
Message-ID: <20201023111740.GA20933@willie-the-truck>
References: <20200930070647.10188-1-yong.wu@mediatek.com>
 <20200930070647.10188-9-yong.wu@mediatek.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20200930070647.10188-9-yong.wu@mediatek.com>
User-Agent: Mutt/1.10.1 (2018-07-13)
Precedence: bulk

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,

Will