[PATCH 5.4 02/62] vfio iommu: Add dma available capability
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: 2021-01-15 12:58:55
Also in:
lkml
Subsystem:
the rest, vfio driver · Maintainers:
Linus Torvalds, Alex Williamson
From: Matthew Rosato <mjrosato@linux.ibm.com>
[ Upstream commit 7d6e1329652ed971d1b6e0e7bea66fba5044e271 ]
The following functional changes were needed for backport:
- vfio_iommu_type1_get_info doesn't exist, call
vfio_iommu_dma_avail_build_caps from vfio_iommu_type1_ioctl.
- As further fallout from this, vfio_iommu_dma_avail_build_caps must
acquire and release the iommu mutex lock. To do so, the return value is
stored in a local variable as in vfio_iommu_iova_build_caps.
Upstream commit description:
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 <mjrosato@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/vfio/vfio_iommu_type1.c | 22 ++++++++++++++++++++++
include/uapi/linux/vfio.h | 15 +++++++++++++++
2 files changed, 37 insertions(+)
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 3b31e83a92155..bc6ba41686fa3 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c@@ -2303,6 +2303,24 @@ static int vfio_iommu_iova_build_caps(struct vfio_iommu *iommu, return ret; } +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; + int ret; + + mutex_lock(&iommu->lock); + cap_dma_avail.header.id = VFIO_IOMMU_TYPE1_INFO_DMA_AVAIL; + cap_dma_avail.header.version = 1; + + cap_dma_avail.avail = iommu->dma_avail; + + ret = vfio_info_add_capability(caps, &cap_dma_avail.header, + sizeof(cap_dma_avail)); + mutex_unlock(&iommu->lock); + return ret; +} + static long vfio_iommu_type1_ioctl(void *iommu_data, unsigned int cmd, unsigned long arg) {
@@ -2349,6 +2367,10 @@ static long vfio_iommu_type1_ioctl(void *iommu_data, info.iova_pgsizes = vfio_pgsize_bitmap(iommu); ret = vfio_iommu_iova_build_caps(iommu, &caps); + + if (!ret) + ret = vfio_iommu_dma_avail_build_caps(iommu, &caps); + if (ret) return ret;
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 9e843a147ead0..cabc93118f9c8 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h@@ -748,6 +748,21 @@ struct vfio_iommu_type1_info_cap_iova_range { struct vfio_iova_range iova_ranges[]; }; +/* + * 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) /**
--
2.27.0