On Tue, Nov 07, 2017 at 02:43:01PM +1100, Alexey Kardashevskiy wrote: > DMA windows can only have a size of power of two on IODA2 hardware and > using memory_hotplug_max() to determine the upper limit won't work > correcly if it returns not power of two value. > > This removes the check as the platform code does this check in > pnv_pci_ioda2_setup_default_config() anyway; the other client is VFIO > and that thing checks against locked_vm limit which prevents the userspace > from locking too much memory. > > It is expected to impact DPDK on machines with non-power-of-two RAM size, > mostly. KVM guests are less likely to be affected as usually guests get > less than half of hosts RAM. > > Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru>
Reviewed-by: David Gibson <da...@gibson.dropbear.id.au>
This _can_ be called with essentially arbitrary window_size via the
VFIO code. However, that should be constrained by the locked memory
limit, which is checked before this gets called.
> ---
> Changes:
> v2:
> * instead of relaxing the check, this simply removes it
> ---
> arch/powerpc/platforms/powernv/pci-ioda.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c
> b/arch/powerpc/platforms/powernv/pci-ioda.c
> index 1de94fb..433cf84 100644
> --- a/arch/powerpc/platforms/powernv/pci-ioda.c
> +++ b/arch/powerpc/platforms/powernv/pci-ioda.c
> @@ -2776,7 +2776,7 @@ static long pnv_pci_ioda2_table_alloc_pages(int nid,
> __u64 bus_offset,
> if (!levels || (levels > POWERNV_IOMMU_MAX_LEVELS))
> return -EINVAL;
>
> - if ((window_size > memory_hotplug_max()) || !is_power_of_2(window_size))
> + if (!is_power_of_2(window_size))
> return -EINVAL;
>
> /* Adjust direct table size from window_size and levels */
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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