Re: [PATCH 2/2] x86/pci: Treat EfiMemoryMappedIO as reservation of ECAM space

[Bjorn Helgaas <helgaas@kernel.org>]

[+cc Sebastian]

On Fri, Nov 03, 2023 at 02:18:58PM -0500, Bjorn Helgaas wrote:
> On Thu, Oct 26, 2023 at 03:53:19PM -0500, Bjorn Helgaas wrote:
> > On Thu, Oct 12, 2023 at 05:33:47PM +0200, Tomasz Pala wrote:
> > > On Tue, Jan 10, 2023 at 12:02:43 -0600, Bjorn Helgaas wrote:
> > > > Normally we reject ECAM space unless it is reported as
> > > > reserved in the E820 table or via a PNP0C02 _CRS method (PCI
> > > > Firmware, r3.3, sec 4.1.2).  This means PCI extended config
> > > > space (offsets 0x100-0xfff) may not be accessible.
> > > > 
> > > > Some firmware doesn't report ECAM space via PNP0C02 _CRS
> > > > methods, but does mention it as an EfiMemoryMappedIO region
> > > > via EFI GetMemoryMap(), which is normally converted to an E820
> > > > entry by a bootloader or EFI stub.
> > > > 
> > > > 07eab0901ede ("efi/x86: Remove EfiMemoryMappedIO from E820
> > > > map"), removes E820 entries that correspond to
> > > > EfiMemoryMappedIO regions because some other firmware uses
> > > > EfiMemoryMappedIO for PCI host bridge windows, and the E820
> > > > entries prevent Linux from allocating BAR space for hot-added
> > > > devices.
> > > > 
> > > > Allow use of ECAM for extended config space when the region is
> > > > covered by an EfiMemoryMappedIO region, even if it's not
> > > > included in E820 or PNP0C02 _CRS.
> > > 
> > > I'm still having a problem initializing ixgbe NICs with pristine
> > > 6.5.7 kernel.
> > 
> > Thanks very much for the report, and sorry for the inconvenience and
> > my delay in looking at it.
> > 
> > > efi: Remove mem63: MMIO range=[0x80000000-0x8fffffff] (256MB) from e820 map
> > > [mem 0x7f800000-0xfed1bfff] available for PCI devices
> > > PCI: MMCONFIG for domain 0000 [bus 00-ff] at [mem 0x80000000-0x8fffffff] (base 0x80000000)
> > > [Firmware Info]: PCI: MMCONFIG at [mem 0x80000000-0x8fffffff] not reserved in ACPI motherboard resources
> > > PCI: MMCONFIG at [mem 0x80000000-0x8fffffff] reserved as EfiMemoryMappedIO
> > > ixgbe 0000:02:00.0: enabling device (0140 -> 0142)
> > > ixgbe 0000:02:00.0: BAR 0: can't reserve [mem 0x80000000-0x8007ffff 64bit]
> > > ixgbe 0000:02:00.0: pci_request_selected_regions failed 0xfffffff0
> > > ixgbe: probe of 0000:02:00.0 failed with error -16
> > 
> > Something is wrong with our allocation scheme.  Both the MMCONFIG
> > region and the ixgbe BAR 0 are at 0x80000000, which obviously cannot
> > work.  Maybe the full dmesg log will have a clue about why we didn't
> > move ixgbe out of the way.
> > 
> > > After disabling the code causing this (using always-false condition:
> > > 		if (size >= 256*1024 && 0) {
> > > ) in the chunk:
> > > 
> > > https://lore.kernel.org/lkml/20221208190341.1560157-2-helgaas@kernel.org/
> > > 
> > > the BAR starts at 0x90000000 (not 0x80000000):
> > > 
> > > efi: Not removing mem63: MMIO range=[0x80000000-0x8fffffff] (262144KB) from e820 map
> > > [...]
> > > [mem 0x90000000-0xfed1bfff] available for PCI devices
> > > [...]
> > > PCI: MMCONFIG for domain 0000 [bus 00-ff] at [mem 0x80000000-0x8fffffff] (base 0x80000000)
> > > PCI: MMCONFIG at [mem 0x80000000-0x8fffffff] reserved as E820 entry
> > > 
> > > and everything seems to work again.
> > > 
> > > 
> > > I've got full system bootup logs from the upstream and worked around,
> > > but I'm not sure if this is OK to attach them (the CC list is long).
> > 
> > Would you mind opening a new report at https://bugzilla.kernel.org,
> > attaching those logs, and responding here with the URL?
> 
> Thanks for the report and the logs, which are attached at
> https://bugzilla.kernel.org/show_bug.cgi?id=218050
> 
> I think the problem is that the MMCONFIG region is at
> [mem 0x80000000-0x8fffffff], and that is *also* included in one of the
> host bridge windows reported via _CRS:
> 
>   PCI: MMCONFIG for domain 0000 [bus 00-ff] at [mem 0x80000000-0x8fffffff] (base 0x80000000)
>   pci_bus 0000:00: root bus resource [mem 0x80000000-0xfbffffff window]
> 
> I'll try to figure out how to deal with that.  In the meantime, would
> you mind attaching the contents of /proc/iomem to the bugzilla?  I
> think you have to cat it as root to get the actual values included.

I attached a debug patch to both bugzilla entries.  If you could
attach the "acpidump" output and (if practical) boot a kernel with the
debug patch and attach the dmesg logs, that would be great.

Bjorn