Commit 7d6e1329 authored by Matthew Rosato's avatar Matthew Rosato Committed by Alex Williamson
Browse files

vfio iommu: Add dma available capability 



Commit 49285593 ("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: default avatarMatthew Rosato <mjrosato@linux.ibm.com>
Reviewed-by: default avatarCornelia Huck <cohuck@redhat.com>
Signed-off-by: default avatarAlex Williamson <alex.williamson@redhat.com>
parent ba4f184e

drivers/vfio/vfio_iommu_type1.c

+17 −0
Original line number Diff line number Diff line
@@ -2609,6 +2609,20 @@ static int vfio_iommu_migration_build_caps(struct vfio_iommu *iommu, 
	return vfio_info_add_capability(caps, &cap_mig.header, sizeof(cap_mig));

}



static int vfio_iommu_dma_avail_build_caps(struct vfio_iommu *iommu,

					   struct vfio_info_cap *caps)

{

	struct vfio_iommu_type1_info_dma_avail cap_dma_avail;



	cap_dma_avail.header.id = VFIO_IOMMU_TYPE1_INFO_DMA_AVAIL;

	cap_dma_avail.header.version = 1;



	cap_dma_avail.avail = iommu->dma_avail;



	return vfio_info_add_capability(caps, &cap_dma_avail.header,

					sizeof(cap_dma_avail));

}



static int vfio_iommu_type1_get_info(struct vfio_iommu *iommu,

				     unsigned long arg)

{
@@ -2641,6 +2655,9 @@ static int vfio_iommu_type1_get_info(struct vfio_iommu *iommu, 


	ret = vfio_iommu_migration_build_caps(iommu, &caps);



	if (!ret)

		ret = vfio_iommu_dma_avail_build_caps(iommu, &caps);



	if (!ret)

		ret = vfio_iommu_iova_build_caps(iommu, &caps);

include/uapi/linux/vfio.h

+15 −0
Original line number Diff line number Diff line
@@ -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)



/**

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