> -----Original Message-----
> From: dev [mailto:dev-boun...@dpdk.org] On Behalf Of Alexey Kardashevskiy
> Sent: Tuesday, August 8, 2017 10:38 AM
> To: Jonas Pfefferle <j...@zurich.ibm.com>; Burakov, Anatoly
> <anatoly.bura...@intel.com>
> Cc: dev@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH] vfio: fix sPAPR IOMMU DMA window size
>
> On 08/08/17 01:11, Jonas Pfefferle wrote:
> > DMA window size needs to be big enough to span all memory segment's
> > physical addresses. We do not need multiple levels of IOMMU tables
> > as we already span ~70TB of physical memory with 16MB hugepages.
> >
> > Signed-off-by: Jonas Pfefferle <j...@zurich.ibm.com>
> > ---
> > lib/librte_eal/linuxapp/eal/eal_vfio.c | 25 ++++++++++++++++++++++---
> > 1 file changed, 22 insertions(+), 3 deletions(-)
> >
> > diff --git a/lib/librte_eal/linuxapp/eal/eal_vfio.c
> > b/lib/librte_eal/linuxapp/eal/eal_vfio.c
> > index 946df7e..8502216 100644
> > --- a/lib/librte_eal/linuxapp/eal/eal_vfio.c
> > +++ b/lib/librte_eal/linuxapp/eal/eal_vfio.c
> > @@ -722,6 +722,18 @@ vfio_type1_dma_map(int vfio_container_fd)
> > return 0;
> > }
> >
> > +static uint64_t
> > +roundup_next_pow2(uint64_t n)
> > +{
> > + uint32_t i;
> > +
> > + n--;
> > + for (i = 1; i < sizeof(n) * CHAR_BIT; i += i)
> > + n |= n >> i;
> > +
> > + return ++n;
> > +}
> > +
>
> wow :)
>
> QEMU does it using __builtin_ctzll() (used below for the page_shift)
> without a loop:
>
> https://git.qemu.org/gitweb.cgi?p=qemu.git;a=blob;f=include/qemu/host-
> utils.h;h=95cf4f4163e50457cdf808263065ca5ef3f935da;hb=f22ab6cb0c47bd2a2785b7d58130949bd7d8d9af#l382
>
>
> Anyway, seems working.
As I remember, there already exists rte_align64pow2().
Konstantin
>
>
> Reviewed-by: Alexey Kardashevskiy <a...@ozlabs.ru>
>
>
>
>
> > static int
> > vfio_spapr_dma_map(int vfio_container_fd)
> > {
> > @@ -759,10 +771,12 @@ vfio_spapr_dma_map(int vfio_container_fd)
> > return -1;
> > }
> >
> > - /* calculate window size based on number of hugepages configured */
> > - create.window_size = rte_eal_get_physmem_size();
> > + /* physicaly pages are sorted descending i.e. ms[0].phys_addr is max */
> > + /* create DMA window from 0 to max(phys_addr + len) */
> > + /* sPAPR requires window size to be a power of 2 */
> > + create.window_size = roundup_next_pow2(ms[0].phys_addr + ms[0].len);
> > create.page_shift = __builtin_ctzll(ms->hugepage_sz);
> > - create.levels = 2;
> > + create.levels = 1;
> >
> > ret = ioctl(vfio_container_fd, VFIO_IOMMU_SPAPR_TCE_CREATE, &create);
> > if (ret) {
> > @@ -771,6 +785,11 @@ vfio_spapr_dma_map(int vfio_container_fd)
> > return -1;
> > }
> >
> > + if (create.start_addr != 0) {
> > + RTE_LOG(ERR, EAL, " DMA window start address != 0\n");
> > + return -1;
> > + }
> > +
> > /* map all DPDK segments for DMA. use 1:1 PA to IOVA mapping */
> > for (i = 0; i < RTE_MAX_MEMSEG; i++) {
> > struct vfio_iommu_type1_dma_map dma_map;
> >
>
>
> --
> Alexey
