From: Yong Wu <yong.wu@mediatek.com>
To: Robin Murphy <robin.murphy@arm.com>
Cc: youlin.pei@mediatek.com, anan.sun@mediatek.com,
Nicolas Boichat <drinkcat@chromium.org>,
srv_heupstream@mediatek.com, Tomasz Figa <tfiga@google.com>,
kernel-team@android.com, linux-kernel@vger.kernel.org,
Krzysztof Kozlowski <krzk@kernel.org>,
chao.hao@mediatek.com, iommu@lists.linux-foundation.org,
linux-mediatek@lists.infradead.org,
Matthias Brugger <matthias.bgg@gmail.com>,
Greg Kroah-Hartman <gregkh@google.com>,
Will Deacon <will@kernel.org>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v3 4/7] iommu: Switch gather->end to unsigned long long
Date: Thu, 17 Dec 2020 10:26:01 +0800 [thread overview]
Message-ID: <1608171961.26323.210.camel@mhfsdcap03> (raw)
In-Reply-To: <16a9565e-5b01-e1c2-0f4a-d06db7f3b093@arm.com>
On Wed, 2020-12-16 at 12:10 +0000, Robin Murphy wrote:
> On 2020-12-16 10:36, Yong Wu wrote:
> > Currently gather->end is "unsigned long" which may be overflow in
> > arch32 in the corner case: 0xfff00000 + 0x100000(iova + size).
> > Although it doesn't affect the size(end - start), it affects the checking
> > "gather->end < end"
>
> This won't help the same situation at the top of a 64-bit address space,
> though, and now that we have TTBR1 support for AArch64 format that is
> definitely a thing. Better to just encode the end address as the actual
> end address, i.e. iova + size - 1. We don't lose anything other than the
> ability to encode zero-sized invalidations that don't make sense anyway.
Thanks for the suggestion. "iova + size - 1" is better. Also I will
change the "size" to "gather->end - gather->start + 1" in the iotlb_sync
of arm-smmu-v3.c and mtk_iommu.c.
>
> Robin.
>
> > Fixes: a7d20dc19d9e ("iommu: Introduce struct iommu_iotlb_gather for batching TLB flushes")
> > Signed-off-by: Yong Wu <yong.wu@mediatek.com>
> > ---
> > include/linux/iommu.h | 5 +++--
> > 1 file changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> > index 794d4085edd3..6e907a95d981 100644
> > --- a/include/linux/iommu.h
> > +++ b/include/linux/iommu.h
> > @@ -178,7 +178,7 @@ enum iommu_dev_features {
> > */
> > struct iommu_iotlb_gather {
> > unsigned long start;
> > - unsigned long end;
> > + unsigned long long end;
> > size_t pgsize;
> > };
> >
> > @@ -537,7 +537,8 @@ static inline void iommu_iotlb_gather_add_page(struct iommu_domain *domain,
> > struct iommu_iotlb_gather *gather,
> > unsigned long iova, size_t size)
> > {
> > - unsigned long start = iova, end = start + size;
> > + unsigned long start = iova;
> > + unsigned long long end = start + size;
> >
> > /*
> > * If the new page is disjoint from the current range or is mapped at
> >
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next prev parent reply other threads:[~2020-12-17 2:26 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-16 10:36 [PATCH v3 0/7] MediaTek IOMMU improve tlb flush performance in map/unmap Yong Wu
2020-12-16 10:36 ` [PATCH v3 1/7] iommu: Move iotlb_sync_map out from __iommu_map Yong Wu
2020-12-23 8:51 ` Christoph Hellwig
2020-12-24 11:27 ` Yong Wu
2020-12-16 10:36 ` [PATCH v3 2/7] iommu: Add iova and size as parameters in iotlb_sync_map Yong Wu
2020-12-16 10:36 ` [PATCH v3 3/7] iommu/mediatek: Add iotlb_sync_map to sync whole the iova range Yong Wu
2020-12-16 10:36 ` [PATCH v3 4/7] iommu: Switch gather->end to unsigned long long Yong Wu
2020-12-16 11:03 ` David Laight
2020-12-17 2:26 ` Yong Wu
2020-12-16 12:10 ` Robin Murphy
2020-12-17 2:26 ` Yong Wu [this message]
2020-12-16 10:36 ` [PATCH v3 5/7] iommu: Allow io_pgtable_tlb ops optional Yong Wu
2021-01-18 16:18 ` Robin Murphy
2020-12-16 10:36 ` [PATCH v3 6/7] iommu/mediatek: Gather iova in iommu_unmap to achieve tlb sync once Yong Wu
2020-12-23 8:56 ` Tomasz Figa
2020-12-23 11:00 ` Robin Murphy
2021-01-08 9:56 ` Tomasz Figa
2021-01-08 9:56 ` Tomasz Figa
2021-01-18 16:35 ` Robin Murphy
2021-01-18 16:58 ` Will Deacon
2021-01-18 17:14 ` Robin Murphy
2020-12-16 10:36 ` [PATCH v3 7/7] iommu/mediatek: Remove the tlb-ops for v7s Yong Wu
2021-01-18 16:39 ` Robin Murphy
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