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Date:	Thu, 20 Mar 2014 13:29:30 +0100
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	"Zhang, Rui" <rui.zhang@...el.com>
Cc:	"Lu, Aaron" <aaron.lu@...el.com>, Borislav Petkov <bp@...en8.de>,
	lkml <linux-kernel@...r.kernel.org>,
	"x86@...nel.org" <x86@...nel.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Linux PCI <linux-pci@...r.kernel.org>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	Yinghai Lu <yinghai@...nel.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Stephane Eranian <eranian@...gle.com>,
	"Yan, Zheng Z" <zheng.z.yan@...el.com>
Subject: Re: Info: mapping multiple BARs. Your kernel is fine.

On Thursday, March 20, 2014 03:03:45 AM Zhang, Rui wrote:
> 
> > -----Original Message-----
> > From: Lu, Aaron
> > Sent: Thursday, March 20, 2014 10:24 AM
> > To: Rafael J. Wysocki; Borislav Petkov
> > Cc: lkml; x86@...nel.org; Bjorn Helgaas; Linux PCI; ACPI Devel Maling
> > List; Zhang, Rui; Yinghai Lu; H. Peter Anvin; Stephane Eranian
> > Subject: Re: Info: mapping multiple BARs. Your kernel is fine.
> > Importance: High
> > 
> > On 03/15/2014 10:15 PM, Rafael J. Wysocki wrote:
> > > [CC list rearranged]
> > >
> > > On Monday, February 24, 2014 05:24:00 PM Borislav Petkov wrote:
> > >> This started happening this morning after booting -rc4+tip, let's
> > add
> > >> *everybody* to CC :-)
> > >>
> > >> We have intel_uncore_init, snb_uncore_imc_init_box, uncore_pci_probe
> > >> and other goodies on the stack.
> > >
> > > I've just gone throught this.
> > >
> > > So the problem is that we have the PNP "system" driver whose only
> > > purpose seems to be to reserve system resources so that the PCI layer
> > > doesn't assign them to new devices on hotplug (disclaimer: I didn't
> > > invent it, I only read the code and comments in there).
> > 
> > And to PCI devices which have uninitialized BARs.
> > 
> > >
> > > It does that for ACPI device objects having the "PNP0C02" and
> > "PNP0C01" IDs.
> > >
> > > Apparently, snb_uncore_imc_init_box() steps on a range already
> > > reserved by that driver on your box.  And this doesn't seem to be a
> > > coincidence, because the ACPI device object in question probably
> > > *does* correspond to the memory controller that the uncore driver
> > attempts to use.
> > >
> > > I'm not sure how to address that right now to be honest.  Arguably,
> > > the PNP "system" driver should be replaced with something saner, but
> > > still the resources it claims need to be kept out of reach of the
> > > PCI's resource allocation code.
> > 
> > The quirk_system_pci_resources is meant to disable PNP devices'
> > resource if they collide with any known PCI device's BAR. I'm not sure
> > why it doesn't work here, perhaps the uncore PCI device doesn't have a
> > BAR that falls in the PNP device's resource window?
> >
> I've talked with Yan Zheng, and I was told that this resource "0xfed10000 - 0xfed15fff"
> is got from PCI device register directly, which is not in its BAR range.
> Thus IMO, it is impossible for PNP layer to be aware of this resource.
> 
> BTW, about drivers/pnp/system.c, if its ONLY purpose is to prevent those
> resources from being allocated to uninitialized PCI devices, then IMO,
> the best way to do this is make PCI bus handle those PNP0C01/PNP0C02
> resources directly, probably via a platform callback, say,
> 1. make drivers/pnp/system.c a no-op for PNPACPI, by checking pnp_dev->protocol.

Then we can drop drivers/pnp/system.c entirely I think.

> 2. introduce acpi_check_reserved_resource() to parsing PNP0C01/PNP0C02 resources.
> 3. in PCI bus, invoke acpi_check_reserved_resource() when assigning
>    resources to PCI devices.

Well, sounds reasonable.


> > >
> > >> ...
> > >> [    0.488998] software IO TLB [mem 0xcac30000-0xcec30000] (64MB)
> > mapped at [ffff8800cac30000-ffff8800cec2ffff]
> > >> [    0.489975] resource map sanity check conflict: 0xfed10000
> > 0xfed15fff 0xfed10000 0xfed13fff pnp 00:01
> > >> [    0.490079] ------------[ cut here ]------------
> > >> [    0.490204] WARNING: CPU: 2 PID: 1 at arch/x86/mm/ioremap.c:171
> > __ioremap_caller+0x372/0x380()
> > >> [    0.490306] Info: mapping multiple BARs. Your kernel is fine.
> > >> [    0.490371] Modules linked in:
> > >> [    0.490558] CPU: 2 PID: 1 Comm: swapper/0 Not tainted 3.14.0-rc4+
> > #1
> > >> [    0.490642] Hardware name: LENOVO 2320CTO/2320CTO, BIOS G2ET86WW
> > (2.06 ) 11/13/2012
> > >> [    0.490742]  00000000000000ab ffff880213d01ad8 ffffffff816112e3
> > 0000000000000006
> > >> [    0.491032]  ffff880213d01b28 ffff880213d01b18 ffffffff8104e9bc
> > ffff880213d01b08
> > >> [    0.491343]  ffffc90000c58000 00000000fed10000 00000000fed10000
> > 0000000000006000
> > >> [    0.491631] Call Trace:
> > >> [    0.493337]  [<ffffffff816112e3>] dump_stack+0x4f/0x7c
> > >> [    0.493420]  [<ffffffff8104e9bc>] warn_slowpath_common+0x8c/0xc0
> > >> [    0.493503]  [<ffffffff8104eaa6>] warn_slowpath_fmt+0x46/0x50
> > >> [    0.493588]  [<ffffffff8103f1e2>] __ioremap_caller+0x372/0x380
> > >> [    0.493674]  [<ffffffff810211a2>] ?
> > snb_uncore_imc_init_box+0x62/0x90
> > >> [    0.493761]  [<ffffffff8103f247>] ioremap_nocache+0x17/0x20
> > >> [    0.493846]  [<ffffffff810211a2>]
> > snb_uncore_imc_init_box+0x62/0x90
> > >> [    0.493933]  [<ffffffff81022925>] uncore_pci_probe+0xe5/0x1e0
> > >> [    0.494020]  [<ffffffff812d487e>] local_pci_probe+0x4e/0xa0
> > >> [    0.494104]  [<ffffffff81418a59>] ? get_device+0x19/0x20
> > >> [    0.494213]  [<ffffffff812d5cd1>] pci_device_probe+0xe1/0x130
> > >> [    0.494300]  [<ffffffff8141d3cb>] driver_probe_device+0x7b/0x240
> > >> [    0.494385]  [<ffffffff8141d63b>] __driver_attach+0xab/0xb0
> > >> [    0.494469]  [<ffffffff8141d590>] ?
> > driver_probe_device+0x240/0x240
> > >> [    0.494551]  [<ffffffff8141b71e>] bus_for_each_dev+0x5e/0x90
> > >> [    0.494634]  [<ffffffff8141cede>] driver_attach+0x1e/0x20
> > >> [    0.494718]  [<ffffffff8141ca57>] bus_add_driver+0x117/0x230
> > >> [    0.494802]  [<ffffffff8141dd34>] driver_register+0x64/0xf0
> > >> [    0.494884]  [<ffffffff812d4c14>] __pci_register_driver+0x64/0x70
> > >> [    0.494972]  [<ffffffff81d0319b>] ? uncore_types_init+0x19c/0x19c
> > >> [    0.495056]  [<ffffffff81d03312>] intel_uncore_init+0x177/0x41c
> > >> [    0.495155]  [<ffffffff81d0319b>] ? uncore_types_init+0x19c/0x19c
> > >> [    0.495242]  [<ffffffff8100029e>] do_one_initcall+0x4e/0x170
> > >> [    0.495326]  [<ffffffff81071100>] ? parse_args+0x60/0x360
> > >> [    0.495411]  [<ffffffff81cfbfb8>]
> > kernel_init_freeable+0x106/0x19a
> > >> [    0.495497]  [<ffffffff81cfb83b>] ? do_early_param+0x86/0x86
> > >> [    0.495582]  [<ffffffff81607ef0>] ? rest_init+0xd0/0xd0
> > >> [    0.495666]  [<ffffffff81607efe>] kernel_init+0xe/0xf0
> > >> [    0.495749]  [<ffffffff81621f6c>] ret_from_fork+0x7c/0xb0
> > >> [    0.495831]  [<ffffffff81607ef0>] ? rest_init+0xd0/0xd0
> > >> [    0.495921] ---[ end trace 428f365c054d9a01 ]---
> > >> [    0.496196] RAPL PMU detected, hw unit 2^-16 Joules, API unit is
> > 2^-32 Joules, 3 fixed counters 163840 ms ovfl timer
> > >> [    0.498598] futex hash table entries: 1024 (order: 5, 131072
> > bytes)
> > >> [    0.498833] audit: initializing netlink subsys (disabled)
> > >> [    0.499024] audit: type=2000 audit(1393259866.477:1): initialized
> > >> ...
> > >>
> > >>
> > >
> 
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-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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