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From: Bjorn Helgaas <helgaas@kernel.org>
To: "Luck, Tony" <tony.luck@intel.com>
Cc: "Williams, Dan J" <dan.j.williams@intel.com>,
	"Liang, Kan" <kan.liang@linux.intel.com>,
	"bhelgaas@google.com" <bhelgaas@google.com>,
	"hdegoede@redhat.com" <hdegoede@redhat.com>,
	"kernelorg@undead.fr" <kernelorg@undead.fr>,
	"kjhambrick@gmail.com" <kjhambrick@gmail.com>,
	"2lprbe78@duck.com" <2lprbe78@duck.com>,
	"nicholas.johnson-opensource@outlook.com.au" 
	<nicholas.johnson-opensource@outlook.com.au>,
	"benoitg@coeus.ca" <benoitg@coeus.ca>,
	"mika.westerberg@linux.intel.com"
	<mika.westerberg@linux.intel.com>,
	"wse@tuxedocomputers.com" <wse@tuxedocomputers.com>,
	"mumblingdrunkard@protonmail.com"
	<mumblingdrunkard@protonmail.com>,
	"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"Box, David E" <david.e.box@intel.com>,
	"Sun, Yunying" <yunying.sun@intel.com>
Subject: Re: Bug report: the extended PCI config space is missed with 6.2-rc2
Date: Thu, 5 Jan 2023 14:37:57 -0600	[thread overview]
Message-ID: <20230105203757.GA1166631@bhelgaas> (raw)
In-Reply-To: <SJ1PR11MB608347C8A95717A8BEE3BF2DFCFA9@SJ1PR11MB6083.namprd11.prod.outlook.com>

On Thu, Jan 05, 2023 at 07:58:47PM +0000, Luck, Tony wrote:
> > Definitely an ambiguity / conflict, but not sure it is a bug when you
> > look at from the perspective of how would an EFI runtime service use
> > ECAM/MMCONFIG space? 
> >
> > Would it be enough to add this clarification in "EFI 2.9 Table 7-6
> > Memory Type Usage after ExitBootServices()"?
> >
> > s/This memory is not used by the OS./This memory is not used by the OS,
> > unless ACPI declares it for another purpose./
> 
> In the case of the EDAC driver there isn't any ACPI declaration.  It just does
> pci_get_device() to find the devices it needs to use with a lookup based on
> vendor-id and device-id.

The EDAC driver wouldn't have any ACPI stuff in it; it's just that
Linux is looking for ACPI info about the ECAM area.

I think the problem here is that the ECAM/MMCONFIG code checks to make
sure the ECAM space is reserved somewhere.  If it doesn't find a
reservation either in E820 [1] or by PNP0C01/PNP0C02 _CRS methods [2],
it decides it's not safe to use ECAM, which means we may only have the
old accessors that can only reach 256 bytes of config space.

Bjorn

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/x86/pci/mmconfig-shared.c?id=v6.1#n447
[2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/x86/pci/mmconfig-shared.c?id=v6.1#n428

  reply	other threads:[~2023-01-05 20:38 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <SJ1PR11MB6083C504335B2DE1B31C440CFCFA9@SJ1PR11MB6083.namprd11.prod.outlook.com>
2023-01-05 18:29 ` Bug report: the extended PCI config space is missed with 6.2-rc2 Bjorn Helgaas
2023-01-05 19:23   ` Liang, Kan
2023-01-05 19:44     ` Bjorn Helgaas
2023-01-05 19:44   ` Dan Williams
2023-01-05 19:58     ` Luck, Tony
2023-01-05 20:37       ` Bjorn Helgaas [this message]
2023-01-05 21:49         ` Luck, Tony
2023-01-05 22:20           ` Bjorn Helgaas
2023-01-05 20:23     ` Bjorn Helgaas
2023-01-05 21:20       ` Dan Williams
2023-01-05 21:35         ` Bjorn Helgaas
2023-01-05 21:43           ` Dan Williams
2023-01-05 21:48             ` Bjorn Helgaas
2023-01-04 14:39 Liang, Kan
2023-01-04 14:50 ` Bjorn Helgaas
2023-01-04 15:45   ` Bjorn Helgaas
2023-01-05 17:42     ` Tony Luck
2023-01-05 17:51       ` Bjorn Helgaas
2023-01-05 22:32 ` Bjorn Helgaas
2023-01-05 23:38   ` Dan Williams
2023-01-06  0:22     ` Luck, Tony
2023-01-06  0:47       ` Bjorn Helgaas
2023-01-06 17:33         ` Bjorn Helgaas
2023-01-06 18:03           ` Luck, Tony
2023-01-06 20:52             ` Bjorn Helgaas
2023-01-06 21:37               ` Luck, Tony
2023-01-06 22:04                 ` Bjorn Helgaas
2023-01-06 22:30                   ` Luck, Tony
2023-01-10  5:43                   ` Sun, Yunying
2023-01-10 18:12                   ` Rafael J. Wysocki
2023-01-10 19:06                     ` Bjorn Helgaas
2023-01-06  0:32     ` Bjorn Helgaas
2023-01-06  0:50   ` Liang, Kan
2023-01-09 12:27   ` Giovanni Cabiddu
2023-01-06  9:44 ` Linux kernel regression tracking (#adding)

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