Re: [PATCH 0/2] PCI: Fix extended config space regression

From: Bjorn Helgaas <helgaas@kernel.org>
To: linux-pci@vger.kernel.org
Cc: "Dan J Williams" <dan.j.williams@intel.com>,
	"Kan Liang" <kan.liang@linux.intel.com>,
	"Tony Luck" <tony.luck@intel.com>,
	"David E Box" <david.e.box@intel.com>,
	"Yunying Sun" <yunying.sun@intel.com>,
	"Dave Jiang" <dave.jiang@intel.com>,
	"Mika Westerberg" <mika.westerberg@linux.intel.com>,
	"Giovanni Cabiddu" <giovanni.cabiddu@intel.com>,
	"Herbert Xu" <herbert@gondor.apana.org.au>,
	"Hans de Goede" <hdegoede@redhat.com>,
	"Florent DELAHAYE" <linuxkernelml@undead.fr>,
	"Konrad J Hambrick" <kjhambrick@gmail.com>,
	"Matt Hansen" <2lprbe78@duck.com>,
	"Nicholas Johnson" <nicholas.johnson-opensource@outlook.com.au>,
	"Benoit Grégoire" <benoitg@coeus.ca>,
	"Werner Sembach" <wse@tuxedocomputers.com>,
	mumblingdrunkard@protonmail.com, linux-kernel@vger.kernel.org,
	"Bjorn Helgaas" <bhelgaas@google.com>
Subject: Re: [PATCH 0/2] PCI: Fix extended config space regression
Date: Wed, 11 Jan 2023 16:30:55 -0600	[thread overview]
Message-ID: <20230111223055.GA1712775@bhelgaas> (raw)
In-Reply-To: <20230110180243.1590045-1-helgaas@kernel.org>

On Tue, Jan 10, 2023 at 12:02:41PM -0600, Bjorn Helgaas wrote:
> From: Bjorn Helgaas <bhelgaas@google.com>
> 
> 07eab0901ede ("efi/x86: Remove EfiMemoryMappedIO from E820 map") appeared
> in v6.2-rc1 and broke extended config space on several machines.
> 
> This broke drivers that use things in extended config space, e.g., perf,
> VSEC telemetry, EDAC, QAT, etc.
> 
> This happened because mmconfig-shared.c checks to see that ECAM space is
> reserved in E820 or ACPI motherboard resources.  If it's not, it assumes
> ECAM doesn't work.  07eab0901ede removed some E820 entries, so it looked
> like ECAM was no longer reserved, so we stopped using it.
> 
> The machines where this broke don't reserve the ECAM in ACPI PNP0C02
> devices (which seems to be what the PCI Firmware spec requires), but they
> do mention it in the EFI memory map as EfiMemoryMappedIO.
> 
> Bjorn Helgaas (2):
>   x86/pci: Simplify is_mmconf_reserved() messages
>   x86/pci: Treat EfiMemoryMappedIO as reservation of ECAM space
> 
>  arch/x86/pci/mmconfig-shared.c | 44 +++++++++++++++++++++++++++++-----
>  1 file changed, 38 insertions(+), 6 deletions(-)

Applied to for-linus for v6.2.  Sorry for the breakage and thank you
very much for the debugging and testing help!