Messages in this thread | | | Subject | Re: [PATCH v4 3/7] iommu/mediatek: Use gather to achieve the tlb range flush | From | Yong Wu <> | Date | Thu, 24 Oct 2019 15:22:32 +0800 |
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On Wed, 2019-10-23 at 17:55 +0100, Will Deacon wrote: > On Wed, Oct 16, 2019 at 11:33:08AM +0800, Yong Wu wrote: > > Use the iommu_gather mechanism to achieve the tlb range flush. > > Gather the iova range in the "tlb_add_page", then flush the merged iova > > range in iotlb_sync. > > > > Suggested-by: Tomasz Figa <tfiga@chromium.org> > > Signed-off-by: Yong Wu <yong.wu@mediatek.com> > > --- > > drivers/iommu/mtk_iommu.c | 12 ++++++++---- > > 1 file changed, 8 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c > > index c2f6c78..81ac95f 100644 > > --- a/drivers/iommu/mtk_iommu.c > > +++ b/drivers/iommu/mtk_iommu.c > > @@ -245,11 +245,9 @@ static void mtk_iommu_tlb_flush_page_nosync(struct iommu_iotlb_gather *gather, > > void *cookie) > > { > > struct mtk_iommu_data *data = cookie; > > - unsigned long flags; > > + struct iommu_domain *domain = &data->m4u_dom->domain; > > > > - spin_lock_irqsave(&data->tlb_lock, flags); > > - mtk_iommu_tlb_add_flush_nosync(iova, granule, granule, true, cookie); > > - spin_unlock_irqrestore(&data->tlb_lock, flags); > > + iommu_iotlb_gather_add_page(domain, gather, iova, granule); > > You need to be careful here, because iommu_iotlb_gather_add_page() can > call iommu_tlb_sync() in some situations and you don't hold the lock.
The mtk_iommu_iotlb_sync below already has the lock in it, so I delete the lock here.
> > > static const struct iommu_flush_ops mtk_iommu_flush_ops = { > > @@ -469,9 +467,15 @@ static void mtk_iommu_iotlb_sync(struct iommu_domain *domain, > > struct iommu_iotlb_gather *gather) > > { > > struct mtk_iommu_data *data = mtk_iommu_get_m4u_data(); > > + size_t length = gather->end - gather->start; > > unsigned long flags; > > > > + if (gather->start == ULONG_MAX) > > + return; > > + > > spin_lock_irqsave(&data->tlb_lock, flags); > > + mtk_iommu_tlb_add_flush_nosync(gather->start, length, gather->pgsize, > > + false, data); > > mtk_iommu_tlb_sync(data); > > spin_unlock_irqrestore(&data->tlb_lock, flags); > > Modulo my comment above, this fixes my previous comment. Given that mainline > is already broken, I guess the runtime bisectability isn't a problem.
As the reply in [2/7]. the mainline is not broken after [2/7], it only go to the previous status before commit(4d689b619445).
After using the iommu_gather, the iova will be the merged range in this iotlb_sync, it is just fit to do the tlb-flush/tlb-sync. then it fixes our potential issue(No tlb-sync for the previous tlb-flush range).
> > Will
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