From 7d6e1329652ed971d1b6e0e7bea66fba5044e271 Mon Sep 17 00:00:00 2001 From: Matthew Rosato Date: Tue, 15 Sep 2020 15:05:18 -0400 Subject: vfio iommu: Add dma available capability Commit 492855939bdb ("vfio/type1: Limit DMA mappings per container") added the ability to limit the number of memory backed DMA mappings. However on s390x, when lazy mapping is in use, we use a very large number of concurrent mappings. Let's provide the current allowable number of DMA mappings to userspace via the IOMMU info chain so that userspace can take appropriate mitigation. Signed-off-by: Matthew Rosato Reviewed-by: Cornelia Huck Signed-off-by: Alex Williamson --- include/uapi/linux/vfio.h | 15 +++++++++++++++ 1 file changed, 15 insertions(+) (limited to 'include/uapi/linux') diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h index 920470502329..3891e03d3af0 100644 --- a/include/uapi/linux/vfio.h +++ b/include/uapi/linux/vfio.h @@ -1039,6 +1039,21 @@ struct vfio_iommu_type1_info_cap_migration { __u64 max_dirty_bitmap_size; /* in bytes */ }; +/* + * The DMA available capability allows to report the current number of + * simultaneously outstanding DMA mappings that are allowed. + * + * The structure below defines version 1 of this capability. + * + * avail: specifies the current number of outstanding DMA mappings allowed. + */ +#define VFIO_IOMMU_TYPE1_INFO_DMA_AVAIL 3 + +struct vfio_iommu_type1_info_dma_avail { + struct vfio_info_cap_header header; + __u32 avail; +}; + #define VFIO_IOMMU_GET_INFO _IO(VFIO_TYPE, VFIO_BASE + 12) /** -- cgit v1.2.3