[edk2-devel] [PATCH v2 1/2] MdeModulePkg: Fixed extra 1 SR-IOV reserved bus
Ni, Ray
ray.ni at intel.com
Fri Oct 14 03:03:10 UTC 2022
Reviewed-by: Ray Ni <ray.ni at intel.com>
> -----Original Message-----
> From: devel at edk2.groups.io <devel at edk2.groups.io> On Behalf Of Foster Nong
> Sent: Wednesday, October 12, 2022 10:37 AM
> To: devel at edk2.groups.io
> Cc: Nong, Foster <foster.nong at intel.com>
> Subject: [edk2-devel] [PATCH v2 1/2] MdeModulePkg: Fixed extra 1 SR-IOV reserved bus
>
> Below code will calculate the reserved bus number for the each PF.
>
> Based on the VF routing ID algorithm, PFRid and LastVF in below code
> already sure that "All VFs and PFs must have distinct Routing IDs".
> PF will be assigned Routing ID based on secBusNumber, ReservedBusNum
> will add into SubBusNumber directly. So the SR-IOV device will be
> assigned bus range as SecBusNumber ~ (SubBusNumber=(SecBusNumber +
> ReservedBusNum)).
> Thus "+1" in below code will cause extra 1 bus, and introduce a bus hole.
>
> PFRid = EFI_PCI_RID (Bus, Device, Func);
> LastVF = PFRid + FirstVFOffset + (PciIoDevice->InitialVFs - 1) * VFStride;
> PciIoDevice->ReservedBusNum = (UINT16)(EFI_PCI_BUS_OF_RID (LastVF) -
> Bus + 1);
>
> In SR-IOV spec, there is a note in section 2.1.2:
> Note: Bus Numbers are a constrained resource. Devices are strongly
> encouraged to avoid leaving “holes” in their Bus Number usage to avoid
> wasting Bus Numbers
>
> So the issue can be fixed with below code change.
> PciIoDevice->ReservedBusNum = (UINT16)(EFI_PCI_BUS_OF_RID (LastVF) -
> Bus);
>
> https://bugzilla.tianocore.org/show_bug.cgi?id=4069
>
> Signed-off-by: Foster Nong <foster.nong at intel.com>
> ---
> MdeModulePkg/Bus/Pci/PciBusDxe/PciEnumeratorSupport.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/MdeModulePkg/Bus/Pci/PciBusDxe/PciEnumeratorSupport.c
> b/MdeModulePkg/Bus/Pci/PciBusDxe/PciEnumeratorSupport.c
> index eb250f6f7b..bc20da1f38 100644
> --- a/MdeModulePkg/Bus/Pci/PciBusDxe/PciEnumeratorSupport.c
> +++ b/MdeModulePkg/Bus/Pci/PciBusDxe/PciEnumeratorSupport.c
> @@ -2425,7 +2425,7 @@ CreatePciIoDevice (
> //
>
> // Calculate ReservedBusNum for this PF
>
> //
>
> - PciIoDevice->ReservedBusNum = (UINT16)(EFI_PCI_BUS_OF_RID (LastVF) - Bus + 1);
>
> + PciIoDevice->ReservedBusNum = (UINT16)(EFI_PCI_BUS_OF_RID (LastVF) - Bus);
>
> }
>
>
>
> DEBUG ((
>
> --
> 2.37.1.windows.1
>
>
>
>
>
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