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Subject[PATCH v2] bus: mvebu-mbus: Avoid setting an undefined window size
Date
The mbus hardware requires a power of two size, and size aligned base.
Currently, if a non-power of two is passed in to the low level routines
they configure the register in a way that results in undefined behaviour.

Call WARN and return EINVAL instead.

Also, update the debugfs routines to show a message if there is an
invalid register setting.

All together this makes the recent problems with silent failure
of PCI very obvious, noisy and debuggable.

Signed-off-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
---
drivers/bus/mvebu-mbus.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)

It would be good to see that these warn's trigger, my system here has
everything aligned..

diff --git a/drivers/bus/mvebu-mbus.c b/drivers/bus/mvebu-mbus.c
index 2ac754e..9578ae3 100644
--- a/drivers/bus/mvebu-mbus.c
+++ b/drivers/bus/mvebu-mbus.c
@@ -56,6 +56,7 @@
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/debugfs.h>
+#include <linux/log2.h>

/*
* DDR target is the same on all platforms.
@@ -266,6 +267,17 @@ static int mvebu_mbus_setup_window(struct mvebu_mbus_state *mbus,
mbus->soc->win_cfg_offset(win);
u32 ctrl, remap_addr;

+ if (!is_power_of_2(size)) {
+ WARN(true, "Invalid MBus window size: 0x%zx\n", size);
+ return -EINVAL;
+ }
+
+ if ((base & (phys_addr_t)(size - 1)) != 0) {
+ WARN(true, "Invalid MBus base/size: %pa len 0x%zx\n", &base,
+ size);
+ return -EINVAL;
+ }
+
ctrl = ((size - 1) & WIN_CTRL_SIZE_MASK) |
(attr << WIN_CTRL_ATTR_SHIFT) |
(target << WIN_CTRL_TGT_SHIFT) |
@@ -413,6 +425,10 @@ static int mvebu_devs_debug_show(struct seq_file *seq, void *v)
win, (unsigned long long)wbase,
(unsigned long long)(wbase + wsize), wtarget, wattr);

+ if (!is_power_of_2(wsize) ||
+ ((wbase & (u64)(wsize - 1)) != 0))
+ seq_puts(seq, " (Invalid base/size!!)");
+
if (win < mbus->soc->num_remappable_wins) {
seq_printf(seq, " (remap %016llx)\n",
(unsigned long long)wremap);
--
1.8.1.2


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