[PATCH AUTOSEL 4.9 40/45] powerpc/eeh: Handle hugepages in ioremap space

From: Sasha Levin
Date: Fri Jul 19 2019 - 00:14:25 EST

From: Oliver O'Halloran <oohall@xxxxxxxxx>

[ Upstream commit 33439620680be5225c1b8806579a291e0d761ca0 ]

In commit 4a7b06c157a2 ("powerpc/eeh: Handle hugepages in ioremap
space") support for using hugepages in the vmalloc and ioremap areas was
enabled for radix. Unfortunately this broke EEH MMIO error checking.

Detection works by inserting a hook which checks the results of the
ioreadXX() set of functions. When a read returns a 0xFFs response we
need to check for an error which we do by mapping the (virtual) MMIO
address back to a physical address, then mapping physical address to a
PCI device via an interval tree.

When translating virt -> phys we currently assume the ioremap space is
only populated by PAGE_SIZE mappings. If a hugepage mapping is found we
emit a WARN_ON(), but otherwise handles the check as though a normal
page was found. In pathalogical cases such as copying a buffer
containing a lot of 0xFFs from BAR memory this can result in the system
not booting because it's too busy printing WARN_ON()s.

There's no real reason to assume huge pages can't be present and we're
prefectly capable of handling them, so do that.

Fixes: 4a7b06c157a2 ("powerpc/eeh: Handle hugepages in ioremap space")
Reported-by: Sachin Sant <sachinp@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Oliver O'Halloran <oohall@xxxxxxxxx>
Tested-by: Sachin Sant <sachinp@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20190710150517.27114-1-oohall@xxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
arch/powerpc/kernel/eeh.c | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/kernel/eeh.c b/arch/powerpc/kernel/eeh.c
index 8336b9016ca9..a7f229e59892 100644
--- a/arch/powerpc/kernel/eeh.c
+++ b/arch/powerpc/kernel/eeh.c
@@ -362,10 +362,19 @@ static inline unsigned long eeh_token_to_phys(unsigned long token)
NULL, &hugepage_shift);
if (!ptep)
return token;
- WARN_ON(hugepage_shift);
- pa = pte_pfn(*ptep) << PAGE_SHIFT;

- return pa | (token & (PAGE_SIZE-1));
+ pa = pte_pfn(*ptep);
+ /* On radix we can do hugepage mappings for io, so handle that */
+ if (hugepage_shift) {
+ pa <<= hugepage_shift;
+ pa |= token & ((1ul << hugepage_shift) - 1);
+ } else {
+ pa <<= PAGE_SHIFT;
+ pa |= token & (PAGE_SIZE - 1);
+ }
+ return pa;