On 2023/06/29 17:05, Ani Sinha wrote:
On Thu, 29 Jun, 2023, 12:17 pm Akihiko Odaki, <akihiko.od...@daynix.com
<mailto:akihiko.od...@daynix.com>> wrote:
On 2023/06/29 13:07, Ani Sinha wrote:
> PCI Express ports only have one slot, so PCI Express devices can
only be
> plugged into slot 0 on a PCIE port. Enforce it.
>
> The change has been tested to not break ARI by instantiating
seven vfs on an
> emulated igb device (the maximum number of vfs the linux igb
driver supports).
> The vfs are seen to have non-zero device/slot numbers in the
conventional
> PCI BDF representation.
>
> CC: jus...@redhat.com <mailto:jus...@redhat.com>
> CC: imamm...@redhat.com <mailto:imamm...@redhat.com>
> CC: akihiko.od...@daynix.com <mailto:akihiko.od...@daynix.com>
>
> Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=2128929
<https://bugzilla.redhat.com/show_bug.cgi?id=2128929>
> Signed-off-by: Ani Sinha <anisi...@redhat.com
<mailto:anisi...@redhat.com>>
> Reviewed-by: Julia Suvorova <jus...@redhat.com
<mailto:jus...@redhat.com>>
> ---
> hw/pci/pci.c | 15 +++++++++++++++
> 1 file changed, 15 insertions(+)
>
> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> index e2eb4c3b4a..0320ac2bb3 100644
> --- a/hw/pci/pci.c
> +++ b/hw/pci/pci.c
> @@ -65,6 +65,7 @@ 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),
> @@ -1190,6 +1191,20 @@ static PCIDevice
*do_pci_register_device(PCIDevice *pci_dev,
> name);
>
> return NULL;
> + } /*
> + * With SRIOV and ARI, vfs can have non-zero slot in the
conventional
> + * PCI interpretation as all five bits reserved for slot
addresses are
> + * also used for function bits for the various vfs. Ignore
that case.
> + * It is too early here to check for ARI capabilities in
the PCI config
> + * space. Hence, we check for a vf device instead.
> + */
Why don't just perform this check after the capabilities are set?
We don't want to allocate resources for wrong device parameters. We want
to error out early. Other checks also are performed at the same place .
It is indeed better to raise an error as early as possible so that we
can avoid allocation and other operations that will be reverted and may
go wrong due to the invalid condition. That should be the reason why
other checks for the address are performed here.
However, in this particular case, we cannot confidently perform the
check here because it is unknown if the ARI capability will be
advertised until the device realization code runs. This can justify
delaying the check after the device realization, unlike the other checks.
Show quoted text
Regards,
Akihiko Odaki
> + else if (!pci_is_vf(pci_dev) &&
> + pcie_has_upstream_port(pci_dev) &&
> + PCI_SLOT(devfn)) {
> + error_setg(errp, "PCI: slot %d is not valid for %s,"
> + " parent device only allows plugging into
slot 0.",
> + PCI_SLOT(devfn), name);
> + return NULL;
> }
>
> pci_dev->devfn = devfn;
