linux-kernel - [PATCH 4.2 109/258] PCI: Clear IORESOURCE

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Date:	Sat, 17 Oct 2015 18:57:02 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org,
	Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Yinghai Lu <yinghai@...nel.org>
Subject: [PATCH 4.2 109/258] PCI: Clear IORESOURCE_UNSET when clipping a bridge window

4.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Bjorn Helgaas <bhelgaas@...gle.com>

commit b838b39e930aa1cfd099ea82ac40ed6d6413af26 upstream.

c770cb4cb505 ("PCI: Mark invalid BARs as unassigned") sets IORESOURCE_UNSET
if we fail to claim a resource.  If we tried to claim a bridge window,
failed, clipped the window, and tried to claim the clipped window, we
failed again because of IORESOURCE_UNSET:

  pci_bus 0000:00: root bus resource [mem 0xc0000000-0xffffffff window]
  pci 0000:00:01.0: can't claim BAR 15 [mem 0xbdf00000-0xddefffff 64bit pref]: no compatible bridge window
  pci 0000:00:01.0: [mem size 0x20000000 64bit pref] clipped to [mem size 0x1df00000 64bit pref]
  pci 0000:00:01.0:   bridge window [mem size 0x1df00000 64bit pref]
  pci 0000:00:01.0: can't claim BAR 15 [mem size 0x1df00000 64bit pref]: no address assigned

The 00:01.0 window started as [mem 0xbdf00000-0xddefffff 64bit pref].  That
starts before the host bridge window [mem 0xc0000000-0xffffffff window], so
we clipped the 00:01.0 window to [mem 0xc0000000-0xddefffff 64bit pref].
But we left it marked IORESOURCE_UNSET, so the second claim failed when it
should have succeeded.

This means downstream devices will also fail for lack of resources, e.g.,
in the bugzilla below,

  radeon 0000:01:00.0: Fatal error during GPU init

Clear IORESOURCE_UNSET when we clip a bridge window.  Also clear
IORESOURCE_UNSET in our copy of the unclipped window so we can see exactly
what the original window was and how it now fits inside the upstream
window.

Fixes: c770cb4cb505 ("PCI: Mark invalid BARs as unassigned")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=85491#c47
Based-on-patch-by: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
Based-on-patch-by: Yinghai Lu <yinghai@...nel.org>
Tested-by: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
Acked-by: Yinghai Lu <yinghai@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/pci/bus.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/pci/bus.c
+++ b/drivers/pci/bus.c
@@ -256,6 +256,8 @@ bool pci_bus_clip_resource(struct pci_de

 		res->start = start;
 		res->end = end;
+		res->flags &= ~IORESOURCE_UNSET;
+		orig_res.flags &= ~IORESOURCE_UNSET;
 		dev_printk(KERN_DEBUG, &dev->dev, "%pR clipped to %pR\n",
 				 &orig_res, res);

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