On Wed, May 02, 2018 at 02:45:57PM +1000, Alexey Kardashevskiy wrote: > At the moment the PPC64/pseries guest only supports 4K/64K/16M IOMMU > pages and POWER8 CPU supports the exact same set of page size so > so far things worked fine. > > However POWER9 supports different set of sizes - 4K/64K/2M/1G and > the last two - 2M and 1G - are not even allowed in the paravirt interface > (RTAS DDW) so we always end up using 64K IOMMU pages, although we could > back guest's 16MB IOMMU pages with 2MB pages on the host. > > This stores the supported host IOMMU page sizes in VFIOContainer and uses > this later when creating a new DMA window. > > There should be no behavioral changes on platforms other than pseries. > > Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru>
What will happen if you try to use this on an older kernel without
your mismatching pagesize changes?
> ---
> include/hw/vfio/vfio-common.h | 1 +
> hw/vfio/common.c | 3 +++
> hw/vfio/spapr.c | 15 ++++++++++++++-
> 3 files changed, 18 insertions(+), 1 deletion(-)
>
> diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
> index d936014..dd8d0d3 100644
> --- a/include/hw/vfio/vfio-common.h
> +++ b/include/hw/vfio/vfio-common.h
> @@ -83,6 +83,7 @@ typedef struct VFIOContainer {
> unsigned iommu_type;
> int error;
> bool initialized;
> + unsigned long pgsizes;
> /*
> * This assumes the host IOMMU can support only a single
> * contiguous IOVA window. We may need to generalize that in
> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
> index 07ffa0b..15ddef2 100644
> --- a/hw/vfio/common.c
> +++ b/hw/vfio/common.c
> @@ -1103,6 +1103,7 @@ static int vfio_connect_container(VFIOGroup *group,
> AddressSpace *as,
> info.iova_pgsizes = 4096;
> }
> vfio_host_win_add(container, 0, (hwaddr)-1, info.iova_pgsizes);
> + container->pgsizes = info.iova_pgsizes;
> } else if (ioctl(fd, VFIO_CHECK_EXTENSION, VFIO_SPAPR_TCE_IOMMU) ||
> ioctl(fd, VFIO_CHECK_EXTENSION, VFIO_SPAPR_TCE_v2_IOMMU)) {
> struct vfio_iommu_spapr_tce_info info;
> @@ -1167,6 +1168,7 @@ static int vfio_connect_container(VFIOGroup *group,
> AddressSpace *as,
> }
>
> if (v2) {
> + container->pgsizes = info.ddw.pgsizes;
> /*
> * There is a default window in just created container.
> * To make region_add/del simpler, we better remove this
> @@ -1181,6 +1183,7 @@ static int vfio_connect_container(VFIOGroup *group,
> AddressSpace *as,
> }
> } else {
> /* The default table uses 4K pages */
> + container->pgsizes = 0x1000;
> vfio_host_win_add(container, info.dma32_window_start,
> info.dma32_window_start +
> info.dma32_window_size - 1,
> diff --git a/hw/vfio/spapr.c b/hw/vfio/spapr.c
> index 259397c..9637ed5 100644
> --- a/hw/vfio/spapr.c
> +++ b/hw/vfio/spapr.c
> @@ -144,11 +144,24 @@ int vfio_spapr_create_window(VFIOContainer *container,
> {
> int ret;
> IOMMUMemoryRegion *iommu_mr = IOMMU_MEMORY_REGION(section->mr);
> - unsigned pagesize = memory_region_iommu_get_min_page_size(iommu_mr);
> + uint64_t pagesize = memory_region_iommu_get_min_page_size(iommu_mr);
> unsigned entries, pages;
> struct vfio_iommu_spapr_tce_create create = { .argsz = sizeof(create) };
>
> /*
> + * The host might not support the guest supported IOMMU page size,
> + * so we will use smaller physical IOMMU pages to back them.
> + */
> + pagesize = 1ULL << ctz64(container->pgsizes & (pagesize | (pagesize -
> 1)));
> + if (!pagesize) {
> + error_report("Host doesn't support page size 0x%"PRIx64
> + ", the supported mask is 0x%lx",
> + memory_region_iommu_get_min_page_size(iommu_mr),
> + container->pgsizes);
> + return -EINVAL;
> + }
> +
> + /*
> * FIXME: For VFIO iommu types which have KVM acceleration to
> * avoid bouncing all map/unmaps through qemu this way, this
> * would be the right place to wire that up (tell the KVM
--
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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