On Sat, Jul 01, 2023 at 04:01:22PM +0900, Akihiko Odaki wrote:
> The function number must be lower than the next function number
> advertised with ARI.
>
> Signed-off-by: Akihiko Odaki <[email protected]>
I don't get this logic at all - where is the limitation coming from?
All I see in the spec is:
Next Function Number - With non-VFs, this field indicates the Function
Number of the next higher
numbered Function in the Device, or 00h if there are no higher numbered
Functions. Function 0 starts
this linked list of Functions.
The presence of Shadow Functions does not affect this field.
For VFs, this field is undefined since VFs are located using First VF
Offset (see § Section 9.3.3.9 ) and VF
Stride (see § Section 9.3.3.10 ).
and
To improve the enumeration performance and create a more deterministic
solution, software can
enumerate Functions through a linked list of Function Numbers. The next
linked list element is
communicated through each Function’s ARI Capability Register.
i. Function 0 acts as the head of a linked list of Function Numbers.
Software detects a
non-Zero Next Function Number field within the ARI Capability Register
as the next
Function within the linked list. Software issues a configuration probe
using the Bus Number
captured by the Device and the Function Number derived from the ARI
Capability Register
to locate the next associated Function’s configuration space.
ii. Function Numbers may be sparse and non-sequential in their
consumption by an ARI
Device.
> ---
> hw/pci/pci.c | 15 +++++++++++++++
> 1 file changed, 15 insertions(+)
>
> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> index e2eb4c3b4a..568665ee42 100644
> --- a/hw/pci/pci.c
> +++ b/hw/pci/pci.c
> @@ -2059,6 +2059,8 @@ static void pci_qdev_realize(DeviceState *qdev, Error
> **errp)
> Error *local_err = NULL;
> bool is_default_rom;
> uint16_t class_id;
> + uint16_t ari;
> + uint16_t nextfn;
>
> /*
> * capped by systemd (see: udev-builtin-net_id.c)
> @@ -2121,6 +2123,19 @@ static void pci_qdev_realize(DeviceState *qdev, Error
> **errp)
> }
> }
>
> + if (pci_is_express(pci_dev)) {
> + ari = pcie_find_capability(pci_dev, PCI_EXT_CAP_ID_ARI);
> + if (ari) {
> + nextfn = (pci_get_long(pci_dev->config + ari + PCI_ARI_CAP) >>
> 8) & 0xff;
> + if (nextfn && (pci_dev->devfn & 0xff) >= nextfn) {
> + error_setg(errp, "PCI: function number %u is not lower than
> ARI next function number %u",
> + pci_dev->devfn & 0xff, nextfn);
> + pci_qdev_unrealize(DEVICE(pci_dev));
> + return;
> + }
> + }
> + }
> +
> if (pci_dev->failover_pair_id) {
> if (!pci_bus_is_express(pci_get_bus(pci_dev))) {
> error_setg(errp, "failover primary device must be on "
> --
> 2.41.0
