On Fri, Aug 15, 2014 at 08:12:24PM +1000, Alexey Kardashevskiy wrote: > The existing KVM_CREATE_SPAPR_TCE ioctl only support 4G windows max. > We are going to add huge DMA windows support so this will create small > window and unexpectedly fail later. > > This disables KVM_CREATE_SPAPR_TCE for windows bigger that 4GB. Since > those windows are normally mapped at the boot time, there will be no > performance impact. > > Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru>
I think perhaps the crucial point here is that the window size
parameter to the kernel ioctl() is only 32-bit, so there's no way of
expressing a TCE window > 4GB.
> ---
> hw/ppc/spapr_iommu.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/hw/ppc/spapr_iommu.c b/hw/ppc/spapr_iommu.c
> index f6e32a4..36f5d27 100644
> --- a/hw/ppc/spapr_iommu.c
> +++ b/hw/ppc/spapr_iommu.c
> @@ -113,11 +113,11 @@ static MemoryRegionIOMMUOps spapr_iommu_ops = {
> static int spapr_tce_table_realize(DeviceState *dev)
> {
> sPAPRTCETable *tcet = SPAPR_TCE_TABLE(dev);
> + uint64_t window_size = tcet->nb_table << tcet->page_shift;
tcet->nb_table is only 32-bit itself, so this isn't going to work as
intended without a cast.
--
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
pgpSiy2WxxfQ6.pgp
Description: PGP signature
