diff options
Diffstat (limited to 'hw/vfio')
| -rw-r--r-- | hw/vfio/pci.c | 36 |
1 files changed, 31 insertions, 5 deletions
diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c index 8fadbcf..035007f 100644 --- a/hw/vfio/pci.c +++ b/hw/vfio/pci.c @@ -28,6 +28,7 @@ #include "config.h" #include "hw/pci/msi.h" #include "hw/pci/msix.h" +#include "hw/pci/pci_bridge.h" #include "qemu/error-report.h" #include "qemu/range.h" #include "sysemu/kvm.h" @@ -1524,13 +1525,38 @@ static int vfio_setup_pcie_cap(VFIOPCIDevice *vdev, int pos, uint8_t size) } if (!pci_bus_is_express(vdev->pdev.bus)) { + PCIBus *bus = vdev->pdev.bus; + PCIDevice *bridge; + /* - * Use express capability as-is on PCI bus. It doesn't make much - * sense to even expose, but some drivers (ex. tg3) depend on it - * and guests don't seem to be particular about it. We'll need - * to revist this or force express devices to express buses if we - * ever expose an IOMMU to the guest. + * Traditionally PCI device assignment exposes the PCIe capability + * as-is on non-express buses. The reason being that some drivers + * simply assume that it's there, for example tg3. However when + * we're running on a native PCIe machine type, like Q35, we need + * to hide the PCIe capability. The reason for this is twofold; + * first Windows guests get a Code 10 error when the PCIe capability + * is exposed in this configuration. Therefore express devices won't + * work at all unless they're attached to express buses in the VM. + * Second, a native PCIe machine introduces the possibility of fine + * granularity IOMMUs supporting both translation and isolation. + * Guest code to discover the IOMMU visibility of a device, such as + * IOMMU grouping code on Linux, is very aware of device types and + * valid transitions between bus types. An express device on a non- + * express bus is not a valid combination on bare metal systems. + * + * Drivers that require a PCIe capability to make the device + * functional are simply going to need to have their devices placed + * on a PCIe bus in the VM. */ + while (!pci_bus_is_root(bus)) { + bridge = pci_bridge_get_device(bus); + bus = bridge->bus; + } + + if (pci_bus_is_express(bus)) { + return 0; + } + } else if (pci_bus_is_root(vdev->pdev.bus)) { /* * On a Root Complex bus Endpoints become Root Complex Integrated |