Re: [PATCH 2/2] PCI: Resources outside their window must set IORESOURCE_UNSET

Geert Uytterhoeven
2025-10-01T11:49:27Z

Hi Ilpo,

On Tue, 30 Sept 2025 at 18:32, Ilpo Järvinen
<ilpo.jarvinen@linux.intel.com> wrote:
> On Tue, 30 Sep 2025, Geert Uytterhoeven wrote:
> > On Fri, 26 Sept 2025 at 04:40, Ilpo Järvinen
> > <ilpo.jarvinen@linux.intel.com> wrote:
> > > PNP resources are checked for conflicts with the other resource in the
> > > system by quirk_system_pci_resources() that walks through all PCI
> > > resources. quirk_system_pci_resources() correctly filters out resource
> > > with IORESOURCE_UNSET.
> > >
> > > Resources that do not reside within their bridge window, however, are
> > > not properly initialized with IORESOURCE_UNSET resulting in bogus
> > > conflicts detected in quirk_system_pci_resources():
> > >
> > > pci 0000:00:02.0: VF BAR 2 [mem 0x00000000-0x1fffffff 64bit pref]
> > > pci 0000:00:02.0: VF BAR 2 [mem 0x00000000-0xdfffffff 64bit pref]: contains BAR 2 for 7 VFs
> > > ...
> > > pci 0000:03:00.0: VF BAR 2 [mem 0x00000000-0x1ffffffff 64bit pref]
> > > pci 0000:03:00.0: VF BAR 2 [mem 0x00000000-0x3dffffffff 64bit pref]: contains BAR 2 for 31 VFs
> > > ...
> > > pnp 00:04: disabling [mem 0xfc000000-0xfc00ffff] because it overlaps 0000:03:00.0 BAR 9 [mem 0x00000000-0x3dffffffff 64bit pref]
> > > pnp 00:05: disabling [mem 0xc0000000-0xcfffffff] because it overlaps 0000:00:02.0 BAR 9 [mem 0x00000000-0xdfffffff 64bit pref]
> > > pnp 00:05: disabling [mem 0xfedc0000-0xfedc7fff] because it overlaps 0000:03:00.0 BAR 9 [mem 0x00000000-0x3dffffffff 64bit pref]
> > > pnp 00:05: disabling [mem 0xfeda0000-0xfeda0fff] because it overlaps 0000:03:00.0 BAR 9 [mem 0x00000000-0x3dffffffff 64bit pref]
> > > pnp 00:05: disabling [mem 0xfeda1000-0xfeda1fff] because it overlaps 0000:03:00.0 BAR 9 [mem 0x00000000-0x3dffffffff 64bit pref]
> > > pnp 00:05: disabling [mem 0xc0000000-0xcfffffff disabled] because it overlaps 0000:03:00.0 BAR 9 [mem 0x00000000-0x3dffffffff 64bit pref]
> > > pnp 00:05: disabling [mem 0xfed20000-0xfed7ffff] because it overlaps 0000:03:00.0 BAR 9 [mem 0x00000000-0x3dffffffff 64bit pref]
> > > pnp 00:05: disabling [mem 0xfed90000-0xfed93fff] because it overlaps 0000:03:00.0 BAR 9 [mem 0x00000000-0x3dffffffff 64bit pref]
> > > pnp 00:05: disabling [mem 0xfed45000-0xfed8ffff] because it overlaps 0000:03:00.0 BAR 9 [mem 0x00000000-0x3dffffffff 64bit pref]
> > > pnp 00:05: disabling [mem 0xfee00000-0xfeefffff] because it overlaps 0000:03:00.0 BAR 9 [mem 0x00000000-0x3dffffffff 64bit pref]
> > >
> > > Mark resources that are not contained within their bridge window with
> > > IORESOURCE_UNSET in __pci_read_base() which resolves the false
> > > positives for the overlap check in quirk_system_pci_resources().
> > >
> > > Fixes: f7834c092c42 ("PNP: Don't check for overlaps with unassigned PCI BARs")
> > > Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
> >
> > Thanks for your patch, which is now commit 06b77d5647a4d6a7 ("PCI:
> > Mark resources IORESOURCE_UNSET when outside bridge windows") in
> > linux-next/master next-20250929 pci/next

> > This replaces the actual resources by their sizes in the boot log on
> > e.g. on R-Car M2-W:
> >
> > pci-rcar-gen2 ee090000.pci: host bridge /soc/pci@ee090000 ranges:
> > pci-rcar-gen2 ee090000.pci: MEM 0x00ee080000..0x00ee08ffff -> 0x00ee080000
> > pci-rcar-gen2 ee090000.pci: PCI: revision 11
> > pci-rcar-gen2 ee090000.pci: PCI host bridge to bus 0000:00
> > pci_bus 0000:00: root bus resource [bus 00]
> > pci_bus 0000:00: root bus resource [mem 0xee080000-0xee08ffff]
> > pci 0000:00:00.0: [1033:0000] type 00 class 0x060000 conventional PCI endpoint
> > -pci 0000:00:00.0: BAR 0 [mem 0xee090800-0xee090bff]
> > -pci 0000:00:00.0: BAR 1 [mem 0x40000000-0x7fffffff pref]
>
> What is going to be the parent of these resources? They don't seem to fall
> under the root bus resource above in which case the output change is
> intentional so they don't appear as if address range would be "okay".

From /proc/iomem:

ee080000-ee08ffff : pci@ee090000
ee080000-ee080fff : 0000:00:01.0
ee080000-ee080fff : ohci_hcd
ee081000-ee0810ff : 0000:00:02.0
ee081000-ee0810ff : ehci_hcd
ee090000-ee090bff : ee090000.pci pci@ee090000
ee0c0000-ee0cffff : pci@ee0d0000
ee0c0000-ee0c0fff : 0001:01:01.0
ee0c0000-ee0c0fff : ohci_hcd
ee0c1000-ee0c10ff : 0001:01:02.0
ee0c1000-ee0c10ff : ehci_hcd

> When IORESOURCE_UNSET is set in a resource, %pR does not print the start
> and end addresses.

Yeah, that's how I found this commit, without bisecting ;-)

> > +pci 0000:00:00.0: BAR 0 [mem size 0x00000400]
> > +pci 0000:00:00.0: BAR 1 [mem size 0x40000000 pref]
> > pci 0000:00:01.0: [1033:0035] type 00 class 0x0c0310 conventional PCI endpoint
> > -pci 0000:00:01.0: BAR 0 [mem 0x00000000-0x00000fff]
> > +pci 0000:00:01.0: BAR 0 [mem size 0x00001000]
>
> For this resource, it's very much intentional. It's a zero-based BAR which
> was left without IORESOURCE_UNSET prior to my patch leading to others part
> of the kernel to think that resource range valid and in use (in your
> case it's so small it wouldn't collide with anything but it wasn't
> properly set up resource, nonetheless).
>
> > pci 0000:00:01.0: supports D1 D2
> > pci 0000:00:01.0: PME# supported from D0 D1 D2 D3hot
> > pci 0000:00:02.0: [1033:00e0] type 00 class 0x0c0320 conventional PCI endpoint
> > -pci 0000:00:02.0: BAR 0 [mem 0x00000000-0x000000ff]
> > +pci 0000:00:02.0: BAR 0 [mem size 0x00000100]
>
> And this as well is very much intentional.
>
> > pci 0000:00:02.0: supports D1 D2
> > pci 0000:00:02.0: PME# supported from D0 D1 D2 D3hot
> > PCI: bus0: Fast back to back transfers disabled
> > pci 0000:00:01.0: BAR 0 [mem 0xee080000-0xee080fff]: assigned
> > pci 0000:00:02.0: BAR 0 [mem 0xee081000-0xee0810ff]: assigned
> > pci_bus 0000:00: resource 4 [mem 0xee080000-0xee08ffff]
> >
> > Is that intentional?
>
> There's also that pci_dbg() in the patch which would show the original
> addresses (print the resource before setting IORESOURCE_UNSET) but to see
> it one would need to enable it with dyndbg=... Bjorn was thinking of
> making that pci_info() though so it would appear always.
>
> Was this the entire PCI related diff? I don't see those 0000:00:00.0 BARs
> getting assigned anywhere.

The above log is almost complete (lacked enabling the device afterwards).

AFAIU, the BARs come from the reg and ranges properties in the
PCI controller nodes;
https://elixir.bootlin.com/linux/v6.17/source/arch/arm/boot/dts/renesas/r8a7791.dtsi#L1562

The full related log for this device, for both instances, with the pci_dbg()
changes to pci_info():

pci-rcar-gen2 ee090000.pci: host bridge /soc/pci@ee090000 ranges:
pci-rcar-gen2 ee090000.pci: MEM 0x00ee080000..0x00ee08ffff
-> 0x00ee080000
pci-rcar-gen2 ee090000.pci: PCI: revision 11
pci-rcar-gen2 ee090000.pci: PCI host bridge to bus 0000:00
pci_bus 0000:00: root bus resource [bus 00]
pci_bus 0000:00: root bus resource [mem 0xee080000-0xee08ffff]
pci 0000:00:00.0: [1033:0000] type 00 class 0x060000 conventional
PCI endpoint
-pci 0000:00:00.0: BAR 0 [mem 0xee090800-0xee090bff]
-pci 0000:00:00.0: BAR 1 [mem 0x40000000-0x7fffffff pref]
+pci 0000:00:00.0: BAR 0 [mem 0xee090800-0xee090bff]: no initial
claim (no window)
+pci 0000:00:00.0: BAR 0 [mem size 0x00000400]
+pci 0000:00:00.0: BAR 1 [mem 0x40000000-0x7fffffff pref]: no
initial claim (no window)
+pci 0000:00:00.0: BAR 1 [mem size 0x40000000 pref]
pci 0000:00:01.0: [1033:0035] type 00 class 0x0c0310 conventional
PCI endpoint
-pci 0000:00:01.0: BAR 0 [mem 0x00000000-0x00000fff]
+pci 0000:00:01.0: BAR 0 [mem 0x00000000-0x00000fff]: no initial
claim (no window)
+pci 0000:00:01.0: BAR 0 [mem size 0x00001000]
pci 0000:00:01.0: supports D1 D2
pci 0000:00:01.0: PME# supported from D0 D1 D2 D3hot
pci 0000:00:02.0: [1033:00e0] type 00 class 0x0c0320 conventional
PCI endpoint
-pci 0000:00:02.0: BAR 0 [mem 0x00000000-0x000000ff]
+pci 0000:00:02.0: BAR 0 [mem 0x00000000-0x000000ff]: no initial
claim (no window)
+pci 0000:00:02.0: BAR 0 [mem size 0x00000100]
pci 0000:00:02.0: supports D1 D2
pci 0000:00:02.0: PME# supported from D0 D1 D2 D3hot
PCI: bus0: Fast back to back transfers disabled
pci 0000:00:01.0: BAR 0 [mem 0xee080000-0xee080fff]: assigned
pci 0000:00:02.0: BAR 0 [mem 0xee081000-0xee0810ff]: assigned
pci_bus 0000:00: resource 4 [mem 0xee080000-0xee08ffff]
pci 0000:00:01.0: enabling device (0140 -> 0142)
pci 0000:00:02.0: enabling device (0140 -> 0142)
pci-rcar-gen2 ee0d0000.pci: host bridge /soc/pci@ee0d0000 ranges:
pci-rcar-gen2 ee0d0000.pci: MEM 0x00ee0c0000..0x00ee0cffff
-> 0x00ee0c0000
pci-rcar-gen2 ee0d0000.pci: PCI: revision 11
pci-rcar-gen2 ee0d0000.pci: PCI host bridge to bus 0001:01
pci_bus 0001:01: root bus resource [bus 01]
pci_bus 0001:01: root bus resource [mem 0xee0c0000-0xee0cffff]
pci 0001:01:00.0: [1033:0000] type 00 class 0x060000 conventional
PCI endpoint
-pci 0001:01:00.0: BAR 0 [mem 0xee0d0800-0xee0d0bff]
-pci 0001:01:00.0: BAR 1 [mem 0x40000000-0x7fffffff pref]
+pci 0001:01:00.0: BAR 0 [mem 0xee0d0800-0xee0d0bff]: no initial
claim (no window)
+pci 0001:01:00.0: BAR 0 [mem size 0x00000400]
+pci 0001:01:00.0: BAR 1 [mem 0x40000000-0x7fffffff pref]: no
initial claim (no window)
+pci 0001:01:00.0: BAR 1 [mem size 0x40000000 pref]
pci 0001:01:01.0: [1033:0035] type 00 class 0x0c0310 conventional
PCI endpoint
-pci 0001:01:01.0: BAR 0 [mem 0x00000000-0x00000fff]
+pci 0001:01:01.0: BAR 0 [mem 0x00000000-0x00000fff]: no initial
claim (no window)
+pci 0001:01:01.0: BAR 0 [mem size 0x00001000]
pci 0001:01:01.0: supports D1 D2
pci 0001:01:01.0: PME# supported from D0 D1 D2 D3hot
pci 0001:01:02.0: [1033:00e0] type 00 class 0x0c0320 conventional
PCI endpoint
-pci 0001:01:02.0: BAR 0 [mem 0x00000000-0x000000ff]
+pci 0001:01:02.0: BAR 0 [mem 0x00000000-0x000000ff]: no initial
claim (no window)
+pci 0001:01:02.0: BAR 0 [mem size 0x00000100]
pci 0001:01:02.0: supports D1 D2
pci 0001:01:02.0: PME# supported from D0 D1 D2 D3hot
PCI: bus1: Fast back to back transfers disabled
pci 0001:01:01.0: BAR 0 [mem 0xee0c0000-0xee0c0fff]: assigned
pci 0001:01:02.0: BAR 0 [mem 0xee0c1000-0xee0c10ff]: assigned
pci_bus 0001:01: resource 4 [mem 0xee0c0000-0xee0cffff]
pci 0001:01:01.0: enabling device (0140 -> 0142)
pci 0001:01:02.0: enabling device (0140 -> 0142)

> You didn't report any issues beyond textual changes in the log, I suppose
> there were none beyond the log differences?

Sorry, I should have done a little bit more testing. This is the funny
on-chip Renesas R-Car Gen2 PCI host controller with integrated OHCI/EHCI
PCI devices. I don't have any USB devices connected, but "lspci -v"
output is the same before/after, and the OHCI/EHCI drivers probe fine.

BTW, I am seeing similar changes on rts7751r2d (qemu SuperH target r2d):

PCI host bridge to bus 0000:00
pci_bus 0000:00: root bus resource [io 0x1000-0x3fffff]
pci_bus 0000:00: root bus resource [mem 0xfd000000-0xfdffffff]
pci_bus 0000:00: No busn resource found for root bus, will use [bus 00-ff]
pci 0000:00:00.0: [1054:350e] type 00 class 0x060000 conventional
PCI endpoint
pci 0000:00:00.0: [Firmware Bug]: BAR 0: invalid; can't size
pci 0000:00:00.0: [Firmware Bug]: BAR 1: invalid; can't size
pci 0000:00:00.0: [Firmware Bug]: BAR 2: invalid; can't size
pci 0000:00:02.0: [10ec:8139] type 00 class 0x020000 conventional
PCI endpoint
-pci 0000:00:02.0: BAR 0 [io 0x0000-0x00ff]
-pci 0000:00:02.0: BAR 1 [mem 0x00000000-0x000000ff]
-pci 0000:00:02.0: ROM [mem 0x00000000-0x0007ffff pref]
+pci 0000:00:02.0: BAR 0 [io 0x0000-0x00ff]: no initial claim (no window)
+pci 0000:00:02.0: BAR 0 [io size 0x0100]
+pci 0000:00:02.0: BAR 1 [mem 0x00000000-0x000000ff]: no initial
claim (no window)
+pci 0000:00:02.0: BAR 1 [mem size 0x00000100]
+pci 0000:00:02.0: ROM [mem 0x00000000-0x0007ffff pref]: no
initial claim (no window)
+pci 0000:00:02.0: ROM [mem size 0x00080000 pref]
pci_bus 0000:00: busn_res: [bus 00-ff] end is updated to 00
pci 0000:00:02.0: ROM [mem 0xfd000000-0xfd07ffff pref]: assigned
pci 0000:00:02.0: BAR 0 [io 0x1000-0x10ff]: assigned
pci 0000:00:02.0: BAR 1 [mem 0xfd080000-0xfd0800ff]: assigned

All of these look legitimate to me, as they all start at zero.

Thanks!

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds