Re: [edk2-devel] [PATCH 1/1] OvmfPkg/PlatformInitLib: pass through reservations from qemu

["Ard Biesheuvel" <ardb@kernel.org>]

On Thu, 12 Jan 2023 at 18:09, Tom Lendacky <thomas.lendacky@amd.com> wrote:
>
> On 12/6/22 23:32, Gerd Hoffmann via groups.io wrote:
> > qemu uses the etc/e820 fw_cfg file not only for memory, but
> > also for reservations.  Handle reservations by adding resource
> > descriptor hobs for them.
> >
> > A typical qemu configuration has a small reservation between
> > lapic and flash:
> >
> >    # sudo cat /proc/iomem
> >    [ ... ]
> >    fee00000-fee00fff : Local APIC
> >    feffc000-feffffff : Reserved          <= HERE
> >    ffc00000-ffffffff : Reserved
> >    [ ... ]
> >
> > Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
>
> On newer versions of Qemu, this patch causes a boot failure on my
> AMD system with the following output:
>
> ...
> PciHostBridgeUtilityInitRootBridge: populated root bus 0, with room for 255 subordinate bus(es)
> RootBridge: PciRoot(0x0)
>    Support/Attr: 70069 / 70069
>      DmaAbove4G: No
> NoExtConfSpace: No
>       AllocAttr: 3 (CombineMemPMem Mem64Decode)
>             Bus: 0 - FF Translation=0
>              Io: 6000 - FFFF Translation=0
>             Mem: C0000000 - FBFFFFFF Translation=0
>      MemAbove4G: E000000000 - FFFFFFFFFF Translation=0
>            PMem: FFFFFFFFFFFFFFFF - 0 Translation=0
>     PMemAbove4G: FFFFFFFFFFFFFFFF - 0 Translation=0
> PciHostBridgeDxe: IntersectMemoryDescriptor: desc [FD00000000, 10000000000) type 1 cap 8000000000026000 conflicts with aperture [E000000000, 10000000000) cap 1
>
> ASSERT_EFI_ERROR (Status = Invalid Parameter)
> ASSERT [PciHostBridgeDxe] /root/kernels/ovmf-build-X64/MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciHostBridge.c(550): !(((INTN)(RETURN_STATUS)(Status)) < 0)
>
> Doing some bisecting, before Qemu patch
>
>     8504f129450b ("i386/pc: relocate 4g start to 1T where applicable")
>
> this issue wasn't observed. And before this OVMF patch, the newer version
> of Qemu doesn't have an issue.
>
> Also, if I add host-phys-bits=true to the Qemu -cpu parameter, then
> the issue isn't observed regardless of Qemu/OVMF level.
>
> I'm hoping someone has an understanding of what is going on and what
> can be done to fix it.
>

Could someone look into this please? Gerd?