On Tue, 18 Feb 2020 18:36:50 +1100
Alexey Kardashevskiy <aik@xxxxxxxxx> wrote:
> So far the only option for a big 64big DMA window was a window located
> at 0x800.0000.0000.0000 (1<<59) which creates problems for devices
> supporting smaller DMA masks.
>
> This exploits a POWER9 PHB option to allow the second DMA window to map
> at 0 and advertises it with a 4GB offset to avoid overlap with
> the default 32bit window.
>
> Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxxxx>
> ---
> include/uapi/linux/vfio.h | 2 ++
> drivers/vfio/vfio_iommu_spapr_tce.c | 10 ++++++++--
> 2 files changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
> index 9e843a147ead..c7f89d47335a 100644
> --- a/include/uapi/linux/vfio.h
> +++ b/include/uapi/linux/vfio.h
> @@ -831,9 +831,11 @@ struct vfio_iommu_spapr_tce_info {
> __u32 argsz;
> __u32 flags;
> #define VFIO_IOMMU_SPAPR_INFO_DDW (1 << 0) /* DDW supported */
> +#define VFIO_IOMMU_SPAPR_INFO_DDW_START (1 << 1) /* DDW offset */
> __u32 dma32_window_start; /* 32 bit window start (bytes) */
> __u32 dma32_window_size; /* 32 bit window size (bytes) */
> struct vfio_iommu_spapr_tce_ddw_info ddw;
> + __u64 dma64_window_start;
> };
>
> #define VFIO_IOMMU_SPAPR_TCE_GET_INFO _IO(VFIO_TYPE, VFIO_BASE + 12)
> diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c
> index 16b3adc508db..4f22be3c4aa2 100644
> --- a/drivers/vfio/vfio_iommu_spapr_tce.c
> +++ b/drivers/vfio/vfio_iommu_spapr_tce.c
> @@ -691,7 +691,7 @@ static long tce_iommu_create_window(struct tce_container *container,
> container->tables[num] = tbl;
>
> /* Return start address assigned by platform in create_table() */
> - *start_addr = tbl->it_offset << tbl->it_page_shift;
> + *start_addr = tbl->it_dmaoff << tbl->it_page_shift;
>
> return 0;
>
> @@ -842,7 +842,13 @@ static long tce_iommu_ioctl(void *iommu_data,
> info.ddw.levels = table_group->max_levels;
> }
>
> - ddwsz = offsetofend(struct vfio_iommu_spapr_tce_info, ddw);
> + ddwsz = offsetofend(struct vfio_iommu_spapr_tce_info,
> + dma64_window_start);
This breaks existing users, now they no longer get the ddw struct
unless their argsz also includes the new dma64 window field.
> +
> + if (info.argsz >= ddwsz) {
> + info.flags |= VFIO_IOMMU_SPAPR_INFO_DDW_START;
> + info.dma64_window_start = table_group->tce64_start;
> + }
This is inconsistent with ddw where we set the flag regardless of
argsz, but obviously only provide the field to the user if they've
provided room for it. Thanks,
Alex
>
> if (info.argsz >= ddwsz)
> minsz = ddwsz;
