On Thu, Jul 31, 2014 at 07:34:06PM +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.
I'm not entirely clear on what you're saying here. Are you saying
that the kernel interface silently truncates a window > 4G, rather
than failing?
If so, that's a kernel bug which should be addressed - obviously we'd
still need this as a workaround for older kernels, but it should be
treated as a workaround, not as the real fix.
> 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>
> ---
> 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;
>
> - if (kvm_enabled()) {
> + if (kvm_enabled() && !(window_size >> 32)) {
> tcet->table = kvmppc_create_spapr_tce(tcet->liobn,
> - tcet->nb_table <<
> - tcet->page_shift,
> + window_size,
> &tcet->fd,
> tcet->vfio_accel);
> }
--
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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