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Re: [PATCH v11 09/12] swiotlb: Add restricted DMA alloc/free support
- To: Claire Chang <tientzu@xxxxxxxxxxxx>
- From: Christoph Hellwig <hch@xxxxxx>
- Date: Wed, 16 Jun 2021 07:18:39 +0200
- Cc: Christoph Hellwig <hch@xxxxxx>, Rob Herring <robh+dt@xxxxxxxxxx>, mpe@xxxxxxxxxxxxxx, Joerg Roedel <joro@xxxxxxxxxx>, Will Deacon <will@xxxxxxxxxx>, Frank Rowand <frowand.list@xxxxxxxxx>, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>, boris.ostrovsky@xxxxxxxxxx, jgross@xxxxxxxx, Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>, benh@xxxxxxxxxxxxxxxxxxx, paulus@xxxxxxxxx, "list@xxxxxxx:IOMMU DRIVERS" <iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx>, sstabellini@xxxxxxxxxx, Robin Murphy <robin.murphy@xxxxxxx>, grant.likely@xxxxxxx, xypron.glpk@xxxxxx, Thierry Reding <treding@xxxxxxxxxx>, mingo@xxxxxxxxxx, bauerman@xxxxxxxxxxxxx, peterz@xxxxxxxxxxxxx, Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>, Saravana Kannan <saravanak@xxxxxxxxxx>, "Rafael J . Wysocki" <rafael.j.wysocki@xxxxxxxxx>, heikki.krogerus@xxxxxxxxxxxxxxx, Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>, Randy Dunlap <rdunlap@xxxxxxxxxxxxx>, Dan Williams <dan.j.williams@xxxxxxxxx>, Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>, linux-devicetree <devicetree@xxxxxxxxxxxxxxx>, lkml <linux-kernel@xxxxxxxxxxxxxxx>, linuxppc-dev@xxxxxxxxxxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxxx, Nicolas Boichat <drinkcat@xxxxxxxxxxxx>, Jim Quinlan <james.quinlan@xxxxxxxxxxxx>, Tomasz Figa <tfiga@xxxxxxxxxxxx>, bskeggs@xxxxxxxxxx, Bjorn Helgaas <bhelgaas@xxxxxxxxxx>, chris@xxxxxxxxxxxxxxxxxx, Daniel Vetter <daniel@xxxxxxxx>, airlied@xxxxxxxx, dri-devel@xxxxxxxxxxxxxxxxxxxxx, intel-gfx@xxxxxxxxxxxxxxxxxxxxx, jani.nikula@xxxxxxxxxxxxxxx, Jianxiong Gao <jxgao@xxxxxxxxxx>, joonas.lahtinen@xxxxxxxxxxxxxxx, linux-pci@xxxxxxxxxxxxxxx, maarten.lankhorst@xxxxxxxxxxxxxxx, matthew.auld@xxxxxxxxx, rodrigo.vivi@xxxxxxxxx, thomas.hellstrom@xxxxxxxxxxxxxxx
- Delivery-date: Wed, 16 Jun 2021 05:18:50 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On Wed, Jun 16, 2021 at 01:10:02PM +0800, Claire Chang wrote:
> On Wed, Jun 16, 2021 at 12:59 PM Christoph Hellwig <hch@xxxxxx> wrote:
> >
> > On Wed, Jun 16, 2021 at 12:04:16PM +0800, Claire Chang wrote:
> > > Just noticed that after propagating swiotlb_force setting into
> > > io_tlb_default_mem->force, the memory allocation behavior for
> > > swiotlb_force will change (i.e. always skipping arch_dma_alloc and
> > > dma_direct_alloc_from_pool).
> >
> > Yes, I think we need to split a "use_for_alloc" flag from the force flag.
>
> How about splitting is_dev_swiotlb_force into is_swiotlb_force_bounce
> (io_tlb_mem->force_bounce) and is_swiotlb_force_alloc
> (io_tlb_mem->force_alloc)?
Yes, something like that. I'd probably not use force for the alloc side
given that we otherwise never allocte from the swiotlb buffer.
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