Re: aarch64 efi boot failures with qemu 6.0+

[Ard Biesheuvel]

(cc Bjorn)

On Mon, 26 Jul 2021 at 11:08, Philippe Mathieu-Daudé <philmd@redhat.com> wrote:
>
> On 7/26/21 12:56 AM, Guenter Roeck wrote:
> > On 7/25/21 3:14 PM, Michael S. Tsirkin wrote:
> >> On Sat, Jul 24, 2021 at 11:52:34AM -0700, Guenter Roeck wrote:
> >>> Hi all,
> >>>
> >>> starting with qemu v6.0, some of my aarch64 efi boot tests no longer
> >>> work. Analysis shows that PCI devices with IO ports do not instantiate
> >>> in qemu v6.0 (or v6.1-rc0) when booting through efi. The problem affects
> >>> (at least) ne2k_pci, tulip, dc390, and am53c974. The problem only
> >>> affects
> >>> aarch64, not x86/x86_64.
> >>>
> >>> I bisected the problem to commit 0cf8882fd0 ("acpi/gpex: Inform os to
> >>> keep firmware resource map"). Since this commit, PCI device BAR
> >>> allocation has changed. Taking tulip as example, the kernel reports
> >>> the following PCI bar assignments when running qemu v5.2.
> >>>
> >>> [    3.921801] pci 0000:00:01.0: [1011:0019] type 00 class 0x020000
> >>> [    3.922207] pci 0000:00:01.0: reg 0x10: [io  0x0000-0x007f]
> >>> [    3.922505] pci 0000:00:01.0: reg 0x14: [mem 0x10000000-0x1000007f]

IIUC, these lines are read back from the BARs

> >>> [    3.927111] pci 0000:00:01.0: BAR 0: assigned [io  0x1000-0x107f]
> >>> [    3.927455] pci 0000:00:01.0: BAR 1: assigned [mem
> >>> 0x10000000-0x1000007f]
> >>>

... and this is the assignment created by the kernel.

> >>> With qemu v6.0, the assignment is reported as follows.
> >>>
> >>> [    3.922887] pci 0000:00:01.0: [1011:0019] type 00 class 0x020000
> >>> [    3.923278] pci 0000:00:01.0: reg 0x10: [io  0x0000-0x007f]
> >>> [    3.923451] pci 0000:00:01.0: reg 0x14: [mem 0x10000000-0x1000007f]
> >>>

The problem here is that Linux, for legacy reasons, does not support
I/O ports <= 0x1000 on PCI, so the I/O assignment created by EFI is
rejected.

This might make sense on x86, where legacy I/O ports may exist, but on
other architectures, this makes no sense.


> >>> and the controller does not instantiate. The problem disapears after
> >>> reverting commit 0cf8882fd0.
> >>>
> >>> Attached is a summary of test runs with various devices and qemu v5.2
> >>> as well as qemu v6.0, and the command line I use for efi boots.
> >>>
> >>> Did commit 0cf8882fd0 introduce a bug, do I now need need some different
> >>> command line to instantiate PCI devices with io ports, or are such
> >>> devices
> >>> simply no longer supported if the system is booted with efi support ?
> >>>
> >>> Thanks,
> >>> Guenter
> >>
> >>
> >> So that commit basically just says don't ignore what efi did.
> >>
> >> The issue's thus likely efi.
> >>
> >
> > I don't see the problem with efi boots on x86 and x86_64.
> > Any idea why that might be the case ?
> >
> > Thanks,
> > Guenter
> >
> >> Cc the maintainer. Philippe can you comment pls?
>
> I'll have a look. Cc'ing Ard for EDK2/Aarch64.
>

So a potential workaround would be to use a different I/O resource
window for ArmVirtPkg, that starts at 0x1000. But I would prefer to
fix Linux instead.


> >>
> >>> ---
> >>> Command line (tulip network interface):
> >>>
> >>> CMDLINE="root=/dev/vda console=ttyAMA0"
> >>> ROOTFS="rootfs.ext2"
> >>>
> >>> qemu-system-aarch64 -M virt -kernel arch/arm64/boot/Image -no-reboot \
> >>>          -m 512 -cpu cortex-a57 -no-reboot \
> >>>          -device tulip,netdev=net0 -netdev user,id=net0 \
> >>>          -bios QEMU_EFI-aarch64.fd \
> >>>          -snapshot \
> >>>          -device virtio-blk-device,drive=d0 \
> >>>          -drive file=${ROOTFS},if=none,id=d0,format=raw \
> >>>          -nographic -serial stdio -monitor none \
> >>>          --append "${CMDLINE}"
> >>>
> >>> ---
> >>> Boot tests with various devices known to work in qemu v5.2.
> >>>
> >>>         v5.2    v6.0    v6.0
> >>>         efi    non-efi    efi
> >>> e1000        pass    pass    pass
> >>> e1000-82544gc    pass    pass    pass
> >>> e1000-82545em    pass    pass    pass
> >>> e1000e        pass    pass    pass
> >>> i82550        pass    pass    pass
> >>> i82557a        pass    pass    pass
> >>> i82557b        pass    pass    pass
> >>> i82557c        pass    pass    pass
> >>> i82558a        pass    pass    pass
> >>> i82559b        pass    pass    pass
> >>> i82559c        pass    pass    pass
> >>> i82559er    pass    pass    pass
> >>> i82562        pass    pass    pass
> >>> i82801        pass    pass    pass
> >>> ne2k_pci    pass    pass    fail    <--
> >>> pcnet        pass    pass    pass
> >>> rtl8139        pass    pass    pass
> >>> tulip        pass    pass    fail    <--
> >>> usb-net        pass    pass    pass
> >>> virtio-net-device
> >>>         pass    pass    pass
> >>> virtio-net-pci    pass    pass    pass
> >>> virtio-net-pci-non-transitional
> >>>         pass    pass    pass
> >>>
> >>> usb-xhci    pass    pass    pass
> >>> usb-ehci    pass    pass    pass
> >>> usb-ohci    pass    pass    pass
> >>> usb-uas-xhci    pass    pass    pass
> >>> virtio        pass    pass    pass
> >>> virtio-blk-pci    pass    pass    pass
> >>> virtio-blk-device
> >>>         pass    pass    pass
> >>> nvme        pass    pass    pass
> >>> sdhci        pass    pass    pass
> >>> dc390        pass    pass    fail    <--
> >>> am53c974    pass    pass    fail    <--
> >>> lsi53c895ai    pass    pass    pass
> >>> mptsas1068    pass    pass    pass
> >>> lsi53c810    pass    pass    pass
> >>> megasas        pass    pass    pass
> >>> megasas-gen2    pass    pass    pass
> >>> virtio-scsi-device
> >>>         pass    pass    pass
> >>> virtio-scsi-pci    pass    pass    pass
> >>
> >
>