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 <jean-philippe@xxxxxxxxxx> Acked-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> > --- > 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 <linux/kexec.h> > #include <linux/of_device.h> > #include <linux/acpi.h> > +#include <linux/virt_iommu.h> > #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 >
