linux-kernel - Re: Bug report: the extended PCI config space is missed with 6.2-rc2

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Message-ID: <20230110190657.GA1600529@bhelgaas>
Date:   Tue, 10 Jan 2023 13:06:57 -0600
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:     "Luck, Tony" <tony.luck@...el.com>,
        "Williams, Dan J" <dan.j.williams@...el.com>,
        "Liang, Kan" <kan.liang@...ux.intel.com>,
        "bhelgaas@...gle.com" <bhelgaas@...gle.com>,
        "hdegoede@...hat.com" <hdegoede@...hat.com>,
        "kernelorg@...ead.fr" <kernelorg@...ead.fr>,
        "kjhambrick@...il.com" <kjhambrick@...il.com>,
        "2lprbe78@...k.com" <2lprbe78@...k.com>,
        "nicholas.johnson-opensource@...look.com.au" 
        <nicholas.johnson-opensource@...look.com.au>,
        "benoitg@...us.ca" <benoitg@...us.ca>,
        "mika.westerberg@...ux.intel.com" <mika.westerberg@...ux.intel.com>,
        "wse@...edocomputers.com" <wse@...edocomputers.com>,
        "mumblingdrunkard@...tonmail.com" <mumblingdrunkard@...tonmail.com>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Box, David E" <david.e.box@...el.com>,
        "Sun, Yunying" <yunying.sun@...el.com>,
        "Jiang, Dave" <dave.jiang@...el.com>
Subject: Re: Bug report: the extended PCI config space is missed with 6.2-rc2

On Tue, Jan 10, 2023 at 07:12:42PM +0100, Rafael J. Wysocki wrote:
> On Friday, January 6, 2023 11:04:49 PM CET Bjorn Helgaas wrote:
> ...
> > The below should work better.
> > 
> > commit 696ac9286d3d ("x86/pci: Treat EfiMemoryMappedIO as reservation of ECAM space")
> > parent 1b929c02afd3
> > Author: Bjorn Helgaas <bhelgaas@...gle.com>
> > Date:   Thu Jan 5 16:02:58 2023 -0600
> > 
> >     x86/pci: Treat EfiMemoryMappedIO as reservation of ECAM space
> >     
> >     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 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.
> >     
> >     Fixes: 07eab0901ede ("efi/x86: Remove EfiMemoryMappedIO from E820 map")
> >     Link: https://lore.kernel.org/r/ac2693d8-8ba3-72e0-5b66-b3ae008d539d@linux.intel.com
> 
> This prints quite a few debug-level messages to dmesg.  I guess you'll post an
> update with fewer of them?

Right, this was a debugging patch.

> In any case, please feel free to add
> 
> Acked-by: Rafael J. Wysocki <rafael@...nel.org>

Thanks!