[PATCH kernel] powerpc/powernv: Fix iommu table size calculation hook for small tables
Alexey Kardashevskiy
aik at ozlabs.ru
Fri Apr 28 16:19:56 AEST 2017
On Thu, 13 Apr 2017 17:05:27 +1000
Alexey Kardashevskiy <aik at ozlabs.ru> 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.
Ping?
>
> Signed-off-by: Alexey Kardashevskiy <aik at ozlabs.ru>
> ---
> arch/powerpc/platforms/powernv/pci-ioda.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
> index 6d0da5dfc955..a0d046adcf45 100644
> --- a/arch/powerpc/platforms/powernv/pci-ioda.c
> +++ b/arch/powerpc/platforms/powernv/pci-ioda.c
> @@ -2538,7 +2538,8 @@ static unsigned long pnv_pci_ioda2_get_table_size(__u32 page_shift,
>
> tce_table_size /= direct_table_size;
> tce_table_size <<= 3;
> - tce_table_size = _ALIGN_UP(tce_table_size, direct_table_size);
> + tce_table_size = max_t(unsigned long,
> + tce_table_size, direct_table_size);
> }
>
> return bytes;
--
Alexey
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