On Thu, 2014-08-21 at 17:47 +0800, arei.gong...@huawei.com wrote:
> From: Gonglei <arei.gong...@huawei.com>
>
> If ARI Forwarding is disabled, according to PCIe spec
> section 7.3.1, only slot 0 with the device attached to
> logic bus representing the link from downstream
> ports and root ports.
>
> So, adding check for PCIe downstream ports and root ports,
> which avoid useless operation, both hotplug and coldplug.
>
> Signed-off-by: Gonglei <arei.gong...@huawei.com>
> ---
> hw/pci/pci.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 51 insertions(+)
>
> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> index daeaeac..aa0af0c 100644
> --- a/hw/pci/pci.c
> +++ b/hw/pci/pci.c
> @@ -773,6 +773,52 @@ static int pci_init_multifunction(PCIBus *bus, PCIDevice
> *dev)
> return 0;
> }
>
> +static int pci_check_pcie_port(PCIBus *bus, PCIDevice *dev)
> +{
> + Object *obj = OBJECT(bus);
> +
> + if (pci_bus_is_root(bus)) {
> + return 0;
> + }
> +
> + if (object_dynamic_cast(obj, TYPE_PCIE_BUS)) {
> + DeviceState *parent = qbus_get_parent(BUS(obj));
> + PCIDevice *pci_dev = PCI_DEVICE(parent);
> + uint8_t port_type;
> + /*
> + * Root ports and downstream ports of switches are the hot
> + * pluggable ports in a PCI Express hierarchy.
> + * PCI Express supports chip-to-chip interconnect, a PCIe link can
> + * only connect one pci device/Switch/EndPoint or PCI-bridge.
> + *
> + * 7.3. Configuration Transaction Rules (PCI Express specification
> 3.0)
> + * 7.3.1. Device Number
> + *
> + * Downstream Ports that do not have ARI Forwarding enabled must
> + * associate only Device 0 with the device attached to the Logical
> Bus
> + * representing the Link from the Port.
> + *
> + * If ARI Forwarding is not enabled on root ports and downstream
> + * ports, only support the devices with slot non-0, regardless of
> + * hotplug or coldplug.
> + */
My interpretation of this section of the spec is that if ARI forwarding
is not available, only the normal 8 functions can be accessed for each
device, eg. device/functions 0.0 -> 0.7 - if a device has more than 8
functions, it will need the second device's namespace, eg. devfn 1.0++,
which would not be routed correctly in a non-ari forward capable device.
As far as I understand, with this fix you restrict an non-ARI capable
switch to only expose one device?
Knut
> + port_type = pcie_cap_get_type(pci_dev);
> + if (port_type == PCI_EXP_TYPE_DOWNSTREAM ||
> + port_type == PCI_EXP_TYPE_ROOT_PORT) {
> + if (!pcie_cap_is_ari_enabled(pci_dev)) {
> + if (PCI_SLOT(dev->devfn) != 0) {
> + error_report("PCIe: Port's ARI Forwarding is disabled, "
> + "device can't be populated in slot %d",
> + PCI_SLOT(dev->devfn));
> + return -1;
> + }
> + }
> + }
> + }
> +
> + return 0;
> +}
> +
> static void pci_config_alloc(PCIDevice *pci_dev)
> {
> int config_size = pci_config_size(pci_dev);
> @@ -827,6 +873,11 @@ static PCIDevice *do_pci_register_device(PCIDevice
> *pci_dev, PCIBus *bus,
>
> pci_dev->bus = bus;
> pci_dev->devfn = devfn;
> +
> + if (pci_check_pcie_port(bus, pci_dev)) {
> + return NULL;
> + }
> +
> dma_as = pci_device_iommu_address_space(pci_dev);
>
> memory_region_init_alias(&pci_dev->bus_master_enable_region,
