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

[Gary Lin <glin@xxxxxxxx>]

On Mon, Apr 25, 2016 at 01:43:01PM +0200, Laszlo Ersek wrote:
> On 04/22/16 16:47, Anthony PERARD wrote:
> > Hi,
> > 
> > Following the switch to MdeModulePkg/Bus/Pci/PciHostBridgeDxe, the pci root
> > bridge does not finish to initialize and breaks under Xen.
> 
> (Adding Ray Ni)
> 
> > 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;
> >  }
> 
> For this, I am to blame; sorry about the regression. Can you please
> submit the change as a standalone patch, and mention commit
> 03845e90cc432 as the one that missed it?
> 
> Also, can you please add the macros to "OvmfPkg/PlatformPei/Xen.h"
> instead, near OVMF_INFO_PHYSICAL_ADDRESS?
> 
> > 
> > 
> > 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) {
> > 
> > 
> > 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 ?
> 
> I think your suggestion that PcdPciDisableBusEnumeration=TRUE causes
> these problems is likely correct. Both of the above issues seem to
> originate from PciHostBridgeDxe's assumption that resources have been
> allocated (i.e., there has been an enumeration).
> 
> Please discuss these questions with Ray -- I guess PciHostBridgeDxe may
> not have received a lot of testing with
> PcdPciDisableBusEnumeration=TRUE. I can imagine that simply considering
> PcdPciDisableBusEnumeration, and acting conditionally upon its value,
> might solve these problems.
> 
I made a quick fix to skip those checks when PcdPciDisableBusEnumeration
is TRUE. Plus the fix for OvmfPkg/PlatformPei/Xen.c, I can now boot to
the UEFI shell.

Ray,

Do you think this is the right way to fix it?

Thanks,

Gary Lin

Attachment: ovmf-xen-quick-fix.patch
Description: Text Data

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