[PATCH] powerpc/eeh: Handle hugepages in ioremap space

Sachin Sant sachinp at linux.vnet.ibm.com
Thu Jul 11 17:47:34 AEST 2019

> On 10-Jul-2019, at 8:35 PM, Oliver O'Halloran <oohall at gmail.com> wrote:
> 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.
> Cc: Nicholas Piggin <npiggin at gmail.com>
> Fixes: 4a7b06c157a2 ("powerpc/eeh: Handle hugepages in ioremap space")
> Reported-by: Sachin Sant <sachinp at linux.vnet.ibm.com>
> Signed-off-by: Oliver O'Halloran <oohall at gmail.com>

Tested-by: Sachin Sant <sachinp at linux.vnet.ibm.com>


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