On Fri, Feb 28, 2020 at 06:25:37PM +0100, Jean-Philippe Brucker wrote:
> Hardware platforms usually describe the IOMMU topology using either
> device-tree pointers or vendor-specific ACPI tables. For virtual
> platforms that don't provide a device-tree, the virtio-iommu device
> contains a description of the endpoints it manages. That information
> allows us to probe endpoints after the IOMMU is probed (possibly as late
> as userspace modprobe), provided it is discovered early enough.
>
> Add a hook to pci_dma_configure(), which returns -EPROBE_DEFER if the
> endpoint is managed by a vIOMMU that will be loaded later, or 0 in any
> other case to avoid disturbing the normal DMA configuration methods.
> When CONFIG_VIRTIO_IOMMU_TOPOLOGY isn't selected, the call to
> virt_dma_configure() is compiled out.
>
> As long as the information is consistent, platforms can provide both a
> device-tree and a built-in topology, and the IOMMU infrastructure is
> able to deal with multiple DMA configuration methods.
>
> Signed-off-by: Jean-Philippe Brucker
Acked-by: Bjorn Helgaas
> ---
> drivers/pci/pci-driver.c | 5 +
> 1 file changed, 5 insertions(+)
>
> diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
> index 0454ca0e4e3f..69303a814f21 100644
> --- a/drivers/pci/pci-driver.c
> +++ b/drivers/pci/pci-driver.c
> @@ -18,6 +18,7 @@
> #include
> #include
> #include
> +#include
> #include "pci.h"
> #include "pcie/portdrv.h"
>
> @@ -1602,6 +1603,10 @@ static int pci_dma_configure(struct device *dev)
> struct device *bridge;
> int ret = 0;
>
> + ret = virt_dma_configure(dev);
> + if (ret)
> + return ret;
> +
> bridge = pci_get_host_bridge_device(to_pci_dev(dev));
>
> if (IS_ENABLED(CONFIG_OF) && bridge->parent &&
> --
> 2.25.0
>
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