[PATCH] powerpc/pci: Only do fixed PHB numbering on powernv
From: Michael Ellerman <mpe@ellerman.id.au>
Date: 2016-08-05 06:41:02
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Linus Torvalds
The recent commit 63a72284b159 ("powerpc/pci: Assign fixed PHB number
based on device-tree properties"), added code to read a 64-bit property
from the device tree, and if not found read a 32-bit property (reg).
There was a bug in the 32-bit case, on big endian machines, due to the
use of the 64-bit value to read the 32-bit property. The cast of &prop
means we end up writing to the high 32-bit of prop, leaving the low
32-bits containing whatever junk was on the stack.
If that junk value was non-zero, and < MAX_PHBS, we would end up using
it as the PHB id.
This exposed a second problem, which is that Xorg can't cope with a
domain number > 256.
So for now drop the fallback to reg, and only use "ibm,opal-phbid" for
PHB numbering.
Fixes: 63a72284b159 ("powerpc/pci: Assign fixed PHB number based on device-tree properties")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---
arch/powerpc/kernel/pci-common.c | 24 +++++++++---------------
1 file changed, 9 insertions(+), 15 deletions(-)
This is my bad. Guilherme limited the reg case to pseries only, but I made it
generic. I tested it on G5, Cell etc. which all booted - but that's not really
a good enough test.
diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c
index f93942b4b6a6..f9c2ffaa1884 100644
--- a/arch/powerpc/kernel/pci-common.c
+++ b/arch/powerpc/kernel/pci-common.c@@ -77,29 +77,23 @@ EXPORT_SYMBOL(get_pci_dma_ops); */ static int get_phb_number(struct device_node *dn) { - int ret, phb_id = -1; + int ret, phb_id; u64 prop; /* - * Try fixed PHB numbering first, by checking archs and reading - * the respective device-tree properties. Firstly, try powernv by - * reading "ibm,opal-phbid", only present in OPAL environment. + * On powernv machines we should have the "ibm,opal-phbid" property, if + * so use that so that PHB numbers are predictable. */ ret = of_property_read_u64(dn, "ibm,opal-phbid", &prop); - if (ret) - ret = of_property_read_u32_index(dn, "reg", 1, (u32 *)&prop); - - if (!ret) + if (ret == 0) { phb_id = (int)(prop & (MAX_PHBS - 1)); - /* We need to be sure to not use the same PHB number twice. */ - if ((phb_id >= 0) && !test_and_set_bit(phb_id, phb_bitmap)) - return phb_id; + /* Make sure never to use the same PHB number twice. */ + if (!test_and_set_bit(phb_id, phb_bitmap)) + return phb_id; + } - /* - * If not pseries nor powernv, or if fixed PHB numbering tried to add - * the same PHB number twice, then fallback to dynamic PHB numbering. - */ + /* If fixed PHB numbering failed, fallback to dynamic PHB numbering. */ phb_id = find_first_zero_bit(phb_bitmap, MAX_PHBS); BUG_ON(phb_id >= MAX_PHBS); set_bit(phb_id, phb_bitmap);
--
2.7.4