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To: Alexey Kardashevskiy <aik@ozlabs.ru>, linuxppc-dev@lists.ozlabs.org
From: Michael Ellerman <patch-notifications@ellerman.id.au>
Cc: Alexey Kardashevskiy <aik@ozlabs.ru>, Paul Mackerras <paulus@samba.org>,
 David Gibson <david@gibson.dropbear.id.au>
Subject: Re: [kernel] powerpc/powernv: Fix iommu table size calculation hook
 for small tables
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Date: Mon,  1 May 2017 12:58:53 +1000 (AEST)
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On Thu, 2017-04-13 at 07:05:27 UTC, Alexey Kardashevskiy wrote:
> When the userspace requests a small TCE table (which takes less than
> the system page size) and more than 1 TCE level, the existing code
> returns a single page size which is a bug as each additional TCE level
> requires at least one page and this is what
> pnv_pci_ioda2_table_alloc_pages() does. And we end up seeing
> WARN_ON(!ret && ((*ptbl)->it_allocated_size != table_size))
> in drivers/vfio/vfio_iommu_spapr_tce.c.
> 
> This replaces incorrect _ALIGN_UP() (which aligns zero up to zero) with
> max_t() to fix the bug.
> 
> Besides removing WARN_ON(), there should be no other changes in
> behaviour.
> 
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/e49a6a2173346d316c0e65d054a3cd

cheers