On Mon, Jun 19, 2023 at 09:29:26PM +0530, Ani Sinha wrote:
> When a device is plugged into a PCIE root port, it can only be plugged into
> slot
> 0. Hotplugging a device into a slot other than slot 0 is invalid and should be
> prevented. This change ensures that we throw an error if the user tries to
> plug
> a device into a pcie root port on any slot other than slot 0.
>
> CC: jus...@redhat.com
> CC: imamm...@redhat.com
> Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=2128929
> Signed-off-by: Ani Sinha
> ---
> hw/pci/pci.c | 16
> 1 file changed, 16 insertions(+)
>
> changelog:
> v2: addressed issue with multifunction pcie root ports. Should allow
> hotplug on functions other than function 0.
> v3: improved commit message.
Weird. You say you improved it but it still only mentions
root port while code works for downstream ports too.
Improve it some more please I guess ;)
> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> index bf38905b7d..66999352cc 100644
> --- a/hw/pci/pci.c
> +++ b/hw/pci/pci.c
> @@ -64,6 +64,7 @@ bool pci_available = true;
> static char *pcibus_get_dev_path(DeviceState *dev);
> static char *pcibus_get_fw_dev_path(DeviceState *dev);
> static void pcibus_reset(BusState *qbus);
> +static bool pcie_has_upstream_port(PCIDevice *dev);
>
> static Property pci_props[] = {
> DEFINE_PROP_PCI_DEVFN("addr", PCIDevice, devfn, -1),
> @@ -1182,6 +1183,11 @@ static PCIDevice *do_pci_register_device(PCIDevice
> *pci_dev,
> } else if (dev->hotplugged &&
> !pci_is_vf(pci_dev) &&
> pci_get_function_0(pci_dev)) {
> +/*
> + * populating function 0 triggers a bus scan from the guest that
> + * exposes other non-zero functions. Hence we need to ensure that
> + * function 0 is available.
available -> wasn't added yet
> + */
> error_setg(errp, "PCI: slot %d function 0 already occupied by %s,"
> " new func %s cannot be exposed to guest.",
> PCI_SLOT(pci_get_function_0(pci_dev)->devfn),
> @@ -1189,6 +1195,16 @@ static PCIDevice *do_pci_register_device(PCIDevice
> *pci_dev,
> name);
>
> return NULL;
> +} else if (dev->hotplugged &&
> + !pci_is_vf(pci_dev) &&
> + pcie_has_upstream_port(pci_dev) && PCI_SLOT(devfn)) {
> +/*
> + * If the device is being plugged into an upstream PCIE port,
No, it's not plugged into an upstream port. It *has* an upstream port.
> + * like a pcie root port, we only support one device at slot 0
this is wrong too, in that "device" here is a pci function, we
support only slot 0, but many functions.
> + */
> +error_setg(errp, "PCI: slot %d is not valid for %s",
Let's not just complain, explain why ;)
> + PCI_SLOT(devfn), name);
> +return NULL;
> }
>
> pci_dev->devfn = devfn;
> --
> 2.39.1
