Re: [Xen-devel] [edk2] OVMF broken under Xen (in PCI initialisation)

["Ni, Ruiyu" <ruiyu.ni@xxxxxxxxx>]

Regards,
Ray

>-----Original Message-----
>From: edk2-devel [mailto:edk2-devel-bounces@xxxxxxxxxxxx] On Behalf Of Anthony 
>PERARD
>Sent: Friday, April 22, 2016 10:48 PM
>To: edk2-devel@xxxxxxxxxxxx
>Cc: Xen Devel <xen-devel@xxxxxxxxxxxxx>
>Subject: [edk2] OVMF broken under Xen (in PCI initialisation)
>
>Hi,
>
>Following the switch to MdeModulePkg/Bus/Pci/PciHostBridgeDxe, the pci root
>bridge does not finish to initialize and breaks under Xen.
>
>There are several issue probably due to the use of
>PcdPciDisableBusEnumeration=TRUE.
>
>First one:
>ASSERT MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciRootBridgeIo.c(99): 
>Bridge->Mem.Limit < 0x0000000100000000ULL
>
>This patch would fix the first assert:
>diff --git a/OvmfPkg/PlatformPei/Xen.c b/OvmfPkg/PlatformPei/Xen.c
>index 7fa9019..15ec7a7 100644
>--- a/OvmfPkg/PlatformPei/Xen.c
>+++ b/OvmfPkg/PlatformPei/Xen.c
>@@ -227,5 +227,11 @@ InitializeXen (
>
>   PcdSetBool (PcdPciDisableBusEnumeration, TRUE);
>
>+  // Values from hvmloader
>+#define PCI_MEM_END         0xFC000000
>+#define HVM_BELOW_4G_MMIO_START 0xF0000000
>+  PcdSet64 (PcdPciMmio32Base, HVM_BELOW_4G_MMIO_START);
>+  PcdSet64 (PcdPciMmio32Size, PCI_MEM_END - HVM_BELOW_4G_MMIO_START);
>+
>   return EFI_SUCCESS;
> }
>
>
>But that not enough, next assert is:
>ASSERT MdeModulePkg/Bus/Pci/PciBusDxe/PciDeviceSupport.c(807): RootBridge != 
>((void *) 0)
>
>I have worked around this one with the following patch. That would
>correspond to how the former implementation in OvmfPkg was initializing the
>struct. Maybe a better way would be to fill ResAllocated under Xen,
>somehow. Under Xen, the ResAllocNode status is not allocated, so no
>Descriptor are created.
>
>diff --git a/MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciRootBridgeIo.c
>b/MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciRootBridgeIo.c
>index cda9b49..eda92b6 100644
>--- a/MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciRootBridgeIo.c
>+++ b/MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciRootBridgeIo.c
>@@ -1509,15 +1509,13 @@ RootBridgeIoConfiguration (
>
>     ResAllocNode = &RootBridge->ResAllocNode[Index];
>
>-    if (ResAllocNode->Status != ResAllocated) {
>-      continue;
>-    }
>-
>     Descriptor->Desc = ACPI_ADDRESS_SPACE_DESCRIPTOR;
>     Descriptor->Len  = sizeof (EFI_ACPI_ADDRESS_SPACE_DESCRIPTOR) - 3;
>+    if (ResAllocNode->Status != ResAllocated) {
>     Descriptor->AddrRangeMin  = ResAllocNode->Base;
>     Descriptor->AddrRangeMax  = ResAllocNode->Base + ResAllocNode->Length - 1;
>     Descriptor->AddrLen       = ResAllocNode->Length;
>+    }
>     switch (ResAllocNode->Type) {
>
I think a more proper fix is to return EFI_UNSUPPORTED without returning any
descriptors when the PcdPciDisableBusEnumeration is TRUE.
Per UEFI Spec, EFI_UNSUPPORTED means "The current configuration of this PCI
root bridge could not be retrieved." It's true when the PCD is true.

>
>That leads to one last assert:
>> QemuVideo: Cirrus 5446 detected
>> InstallProtocolInterface: 09576E91-6D3F-11D2-8E39-00A0C969723B 7B9EF598
>> Adding Mode 0 as Cirrus Internal Mode 0: 640x480, 32-bit, 60 Hz
>> Adding Mode 1 as Cirrus Internal Mode 1: 800x600, 32-bit, 60 Hz
>> Adding Mode 2 as Cirrus Internal Mode 2: 1024x768, 24-bit, 60 Hz
>> PixelBlueGreenRedReserved8BitPerColor
>> ASSERT 
>> /local/home/sheep/work/ovmf/MdeModulePkg/Bus/Pci/PciBusDxe/PciIo.c(1789): 
>> ((BOOLEAN)(0==1))
>For this one, I've workaround by reverting patch 7b0a1ea
>(MdeModuelPkg/PciBus: Return AddrTranslationOffset in GetBarAttributes).
>That issue was introduce while still using the USE_OLD_PCI_HOST.
>
>Any idee or pointer on how to fix those issues ?

When the PciRootBridgeIo.Configuration() returns EFI_UNSUPPORTED, this assertion
can be fixed as well. Correct?
>
>Thanks,
>
>--
>Anthony PERARD
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>edk2-devel@xxxxxxxxxxxx
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