[+cc Yijing, Dave J, Dave M, Alex]
On Fri, May 01, 2015 at 01:32:12PM -0500, [email protected] wrote:
> From: Will Davis <[email protected]>
>
> Hi,
>
> This patch series adds DMA APIs to map and unmap a struct resource to and from
> a PCI device's IOVA domain, and implements the AMD, Intel, and nommu versions
> of these interfaces.
>
> This solves a long-standing problem with the existing DMA-remapping
> interfaces,
> which require that a struct page be given for the region to be mapped into a
> device's IOVA domain. This requirement cannot support peer device BAR ranges,
> for which no struct pages exist.
>
> The underlying implementations of map_page and map_sg convert the struct page
> into its physical address anyway, so we just need a way to route the physical
> address of the BAR region to these implementations. The new interfaces do this
> by taking the struct resource describing a device's BAR region, from which the
> physical address is derived.
>
> The Intel and nommu versions have been verified on a dual Intel Xeon E5405
> workstation. I'm in the process of obtaining hardware to test the AMD version
> as well. Please review.
I think we currently assume there's no peer-to-peer traffic.
I don't know whether changing that will break anything, but I'm concerned
about these:
- PCIe MPS configuration (see pcie_bus_configure_settings()).
- PCIe ACS, e.g., pci_acs_enabled(). My guess is that this one is OK,
but Alex would know better.
- dma_addr_t. Currently dma_addr_t is big enough to hold any address
returned from the DMA API. That's not necessarily big enough to hold a
PCI bus address, e.g., a raw BAR value.
> Will Davis (6):
> dma-debug: add checking for map/unmap_resource
> DMA-API: Introduce dma_(un)map_resource
> dma-mapping: pci: add pci_(un)map_resource
> iommu/amd: Implement (un)map_resource
> iommu/vt-d: implement (un)map_resource
> x86: add pci-nommu implementation of map_resource
>
> arch/x86/kernel/pci-nommu.c | 17 +++++++
> drivers/iommu/amd_iommu.c | 76
> ++++++++++++++++++++++++++------
> drivers/iommu/intel-iommu.c | 18 ++++++++
> include/asm-generic/dma-mapping-broken.h | 9 ++++
> include/asm-generic/dma-mapping-common.h | 34 ++++++++++++++
> include/asm-generic/pci-dma-compat.h | 14 ++++++
> include/linux/dma-debug.h | 20 +++++++++
> include/linux/dma-mapping.h | 7 +++
> lib/dma-debug.c | 48 ++++++++++++++++++++
> 9 files changed, 230 insertions(+), 13 deletions(-)
>
> --
> 2.3.7
>
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