| Message ID | 1600122331-12181-2-git-send-email-mjrosato@linux.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] vfio iommu: Add dma available capability | expand |
On Mon, 14 Sep 2020 18:25:31 -0400 Matthew Rosato <mjrosato@linux.ibm.com> wrote: > 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> > --- > drivers/vfio/vfio_iommu_type1.c | 17 +++++++++++++++++ > include/uapi/linux/vfio.h | 16 ++++++++++++++++ > 2 files changed, 33 insertions(+) (...) > diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h > index 9204705..a8cc4a5 100644 > --- a/include/uapi/linux/vfio.h > +++ b/include/uapi/linux/vfio.h > @@ -1039,6 +1039,22 @@ 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 structures below define version 1 of this capability. "The structure below defines..." ? > + * > + * max: specifies the maximum number of outstanding DMA mappings allowed. I think you forgot to tweak that one: "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) > > /**
On 9/15/20 5:44 AM, Cornelia Huck wrote: > On Mon, 14 Sep 2020 18:25:31 -0400 > Matthew Rosato <mjrosato@linux.ibm.com> wrote: > >> 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> >> --- >> drivers/vfio/vfio_iommu_type1.c | 17 +++++++++++++++++ >> include/uapi/linux/vfio.h | 16 ++++++++++++++++ >> 2 files changed, 33 insertions(+) > > (...) > >> diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h >> index 9204705..a8cc4a5 100644 >> --- a/include/uapi/linux/vfio.h >> +++ b/include/uapi/linux/vfio.h >> @@ -1039,6 +1039,22 @@ 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 structures below define version 1 of this capability. > > "The structure below defines..." ? > OK >> + * >> + * max: specifies the maximum number of outstanding DMA mappings allowed. > > I think you forgot to tweak that one: > > "avail: specifies the current number of outstanding DMA mappings allowed." > > ? Yep, that's a leftover from v1 :( > >> + */ >> +#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) >> >> /** >
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c index 5fbf0c1..15e21db 100644 --- a/drivers/vfio/vfio_iommu_type1.c +++ b/drivers/vfio/vfio_iommu_type1.c @@ -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) { @@ -2642,6 +2656,9 @@ 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); mutex_unlock(&iommu->lock); diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h index 9204705..a8cc4a5 100644 --- a/include/uapi/linux/vfio.h +++ b/include/uapi/linux/vfio.h @@ -1039,6 +1039,22 @@ 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 structures below define version 1 of this capability. + * + * max: specifies the maximum 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) /**
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> --- drivers/vfio/vfio_iommu_type1.c | 17 +++++++++++++++++ include/uapi/linux/vfio.h | 16 ++++++++++++++++ 2 files changed, 33 insertions(+)