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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@intel.com>
Reviewed-by: Ray Ni <ray.ni@intel.com>
This commit is contained in:
Foster Nong 2022-10-12 10:36:55 +08:00 committed by mergify[bot]
parent e0200cc47a
commit 4aa7e66c06
1 changed files with 1 additions and 1 deletions
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2
MdeModulePkg/Bus/Pci/PciBusDxe/PciEnumeratorSupport.c
View File

@ -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 ((