From 4aa7e66c06f8b837845aff2afd7c1c0b35d9afba Mon Sep 17 00:00:00 2001 From: Foster Nong Date: Wed, 12 Oct 2022 10:36:55 +0800 Subject: [PATCH] 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 Reviewed-by: Ray Ni --- 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 (( -- 2.39.5