From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bjorn Helgaas Subject: Re: [PATCH v2 2/3] PCI: Add DMA configuration for virtual platforms Date: Wed, 18 Mar 2020 16:10:02 -0500 Message-ID: <20200318211002.GA237687@google.com> References: <20200228172537.377327-3-jean-philippe@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20200228172537.377327-3-jean-philippe@linaro.org> Sender: linux-pci-owner@vger.kernel.org To: Jean-Philippe Brucker Cc: iommu@lists.linux-foundation.org, virtualization@lists.linux-foundation.org, linux-pci@vger.kernel.org, joro@8bytes.org, mst@redhat.com, jasowang@redhat.com, kevin.tian@intel.com, sebastien.boeuf@intel.com, eric.auger@redhat.com, jacob.jun.pan@intel.com, robin.murphy@arm.com List-Id: virtualization@lists.linuxfoundation.org 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 >