| Message ID | 1585587044-2408-6-git-send-email-kwankhede@nvidia.com |
|---|---|
| State | New |
| Headers | show |
| Series | KABIs to support migration for VFIO devices | expand |
On Mon, 30 Mar 2020 22:20:42 +0530 Kirti Wankhede <kwankhede@nvidia.com> wrote: > DMA mapped pages, including those pinned by mdev vendor drivers, might > get unpinned and unmapped while migration is active and device is still > running. For example, in pre-copy phase while guest driver could access > those pages, host device or vendor driver can dirty these mapped pages. > Such pages should be marked dirty so as to maintain memory consistency > for a user making use of dirty page tracking. > > To get bitmap during unmap, user should allocate memory for bitmap, set > size of allocated memory, set page size to be considered for bitmap and > set flag VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP. > > Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com> > Reviewed-by: Neo Jia <cjia@nvidia.com> > --- > drivers/vfio/vfio_iommu_type1.c | 55 ++++++++++++++++++++++++++++++++++++++--- > include/uapi/linux/vfio.h | 10 ++++++++ > 2 files changed, 61 insertions(+), 4 deletions(-) > > diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c > index 5efebc2b60e1..266550bd7307 100644 > --- a/drivers/vfio/vfio_iommu_type1.c > +++ b/drivers/vfio/vfio_iommu_type1.c > @@ -983,7 +983,8 @@ static int verify_bitmap_size(uint64_t npages, uint64_t bitmap_size) > } > > static int vfio_dma_do_unmap(struct vfio_iommu *iommu, > - struct vfio_iommu_type1_dma_unmap *unmap) > + struct vfio_iommu_type1_dma_unmap *unmap, > + struct vfio_bitmap *bitmap) > { > uint64_t mask; > struct vfio_dma *dma, *dma_last = NULL; > @@ -1034,6 +1035,10 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu, > * will be returned if these conditions are not met. The v2 interface > * will only return success and a size of zero if there were no > * mappings within the range. > + * > + * When VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP flag is set, unmap request > + * must be for single mapping. Multiple mappings with this flag set is > + * not supported. > */ > if (iommu->v2) { > dma = vfio_find_dma(iommu, unmap->iova, 1); > @@ -1041,6 +1046,14 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu, > ret = -EINVAL; > goto unlock; > } > + > + if ((unmap->flags & VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP) && > + dma && > + (dma->iova != unmap->iova || dma->size != unmap->size)) { I think your intention was to return error if the user asked for the dirty bitmap and the requested unmap range doesn't exactly match the vfio_dma. Not finding a vfio_dma should therefore also be an error. For example, if we had a single mapping at {0x1000-0x1fff} and the user unmapped with dirty bitmap {0x0-0x2fff}, that should return an error, but it's not caught by the above because there is no vfio_dma @0x0. Therefore I think you want: ((unmap->flags & VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP) && (!dma || dma->iova != unmap->iova || dma->size != unmap->size)) Right? Thanks, Alex > + ret = -EINVAL; > + goto unlock; > + } > + > dma = vfio_find_dma(iommu, unmap->iova + unmap->size - 1, 0); > if (dma && dma->iova + dma->size != unmap->iova + unmap->size) { > ret = -EINVAL; > @@ -1058,6 +1071,11 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu, > if (dma->task->mm != current->mm) > break; > > + if ((unmap->flags & VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP) && > + iommu->dirty_page_tracking) > + vfio_iova_dirty_bitmap(iommu, dma->iova, dma->size, > + bitmap->pgsize, bitmap->data); > + > if (!RB_EMPTY_ROOT(&dma->pfn_list)) { > struct vfio_iommu_type1_dma_unmap nb_unmap; > > @@ -2419,17 +2437,46 @@ static long vfio_iommu_type1_ioctl(void *iommu_data, > > } else if (cmd == VFIO_IOMMU_UNMAP_DMA) { > struct vfio_iommu_type1_dma_unmap unmap; > - long ret; > + struct vfio_bitmap bitmap = { 0 }; > + int ret; > > minsz = offsetofend(struct vfio_iommu_type1_dma_unmap, size); > > if (copy_from_user(&unmap, (void __user *)arg, minsz)) > return -EFAULT; > > - if (unmap.argsz < minsz || unmap.flags) > + if (unmap.argsz < minsz || > + unmap.flags & ~VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP) > return -EINVAL; > > - ret = vfio_dma_do_unmap(iommu, &unmap); > + if (unmap.flags & VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP) { > + unsigned long pgshift; > + size_t iommu_pgsize = > + (size_t)1 << __ffs(vfio_pgsize_bitmap(iommu)); > + > + if (unmap.argsz < (minsz + sizeof(bitmap))) > + return -EINVAL; > + > + if (copy_from_user(&bitmap, > + (void __user *)(arg + minsz), > + sizeof(bitmap))) > + return -EFAULT; > + > + /* allow only min supported pgsize */ > + if (bitmap.pgsize != iommu_pgsize) > + return -EINVAL; > + if (!access_ok((void __user *)bitmap.data, bitmap.size)) > + return -EINVAL; > + > + pgshift = __ffs(bitmap.pgsize); > + ret = verify_bitmap_size(unmap.size >> pgshift, > + bitmap.size); > + if (ret) > + return ret; > + > + } > + > + ret = vfio_dma_do_unmap(iommu, &unmap, &bitmap); > if (ret) > return ret; > > diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h > index 5f359c63f5ef..e3cbf8b78623 100644 > --- a/include/uapi/linux/vfio.h > +++ b/include/uapi/linux/vfio.h > @@ -1048,12 +1048,22 @@ struct vfio_bitmap { > * field. No guarantee is made to the user that arbitrary unmaps of iova > * or size different from those used in the original mapping call will > * succeed. > + * VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP should be set to get dirty bitmap > + * before unmapping IO virtual addresses. When this flag is set, user must > + * provide data[] as structure vfio_bitmap. User must allocate memory to get > + * bitmap and must set size of allocated memory in vfio_bitmap.size field. > + * A bit in bitmap represents one page of user provided page size in 'pgsize', > + * consecutively starting from iova offset. Bit set indicates page at that > + * offset from iova is dirty. Bitmap of pages in the range of unmapped size is > + * returned in vfio_bitmap.data > */ > struct vfio_iommu_type1_dma_unmap { > __u32 argsz; > __u32 flags; > +#define VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP (1 << 0) > __u64 iova; /* IO virtual address */ > __u64 size; /* Size of mapping (bytes) */ > + __u8 data[]; > }; > > #define VFIO_IOMMU_UNMAP_DMA _IO(VFIO_TYPE, VFIO_BASE + 14)
On 3/31/2020 3:04 AM, Alex Williamson wrote: > On Mon, 30 Mar 2020 22:20:42 +0530 > Kirti Wankhede <kwankhede@nvidia.com> wrote: > >> DMA mapped pages, including those pinned by mdev vendor drivers, might >> get unpinned and unmapped while migration is active and device is still >> running. For example, in pre-copy phase while guest driver could access >> those pages, host device or vendor driver can dirty these mapped pages. >> Such pages should be marked dirty so as to maintain memory consistency >> for a user making use of dirty page tracking. >> >> To get bitmap during unmap, user should allocate memory for bitmap, set >> size of allocated memory, set page size to be considered for bitmap and >> set flag VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP. >> >> Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com> >> Reviewed-by: Neo Jia <cjia@nvidia.com> >> --- >> drivers/vfio/vfio_iommu_type1.c | 55 ++++++++++++++++++++++++++++++++++++++--- >> include/uapi/linux/vfio.h | 10 ++++++++ >> 2 files changed, 61 insertions(+), 4 deletions(-) >> >> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c >> index 5efebc2b60e1..266550bd7307 100644 >> --- a/drivers/vfio/vfio_iommu_type1.c >> +++ b/drivers/vfio/vfio_iommu_type1.c >> @@ -983,7 +983,8 @@ static int verify_bitmap_size(uint64_t npages, uint64_t bitmap_size) >> } >> >> static int vfio_dma_do_unmap(struct vfio_iommu *iommu, >> - struct vfio_iommu_type1_dma_unmap *unmap) >> + struct vfio_iommu_type1_dma_unmap *unmap, >> + struct vfio_bitmap *bitmap) >> { >> uint64_t mask; >> struct vfio_dma *dma, *dma_last = NULL; >> @@ -1034,6 +1035,10 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu, >> * will be returned if these conditions are not met. The v2 interface >> * will only return success and a size of zero if there were no >> * mappings within the range. >> + * >> + * When VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP flag is set, unmap request >> + * must be for single mapping. Multiple mappings with this flag set is >> + * not supported. >> */ >> if (iommu->v2) { >> dma = vfio_find_dma(iommu, unmap->iova, 1); >> @@ -1041,6 +1046,14 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu, >> ret = -EINVAL; >> goto unlock; >> } >> + >> + if ((unmap->flags & VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP) && >> + dma && >> + (dma->iova != unmap->iova || dma->size != unmap->size)) { > > > I think your intention was to return error if the user asked for the > dirty bitmap and the requested unmap range doesn't exactly match the > vfio_dma. Not finding a vfio_dma should therefore also be an error. > For example, if we had a single mapping at {0x1000-0x1fff} and the user > unmapped with dirty bitmap {0x0-0x2fff}, that should return an error, > but it's not caught by the above because there is no vfio_dma @0x0. > Therefore I think you want: > > ((unmap->flags & VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP) && > (!dma || dma->iova != unmap->iova || dma->size != unmap->size)) > > Right? Thanks, > Yes, updating check. Is !dma here also error case when VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP flag is not set? DMA_UNMAP ioctl returns how much was unmapped, from user space perspective this would be from start of range (unmap->iova), right? Thanks, Kirti
On Wed, 1 Apr 2020 00:16:13 +0530 Kirti Wankhede <kwankhede@nvidia.com> wrote: > On 3/31/2020 3:04 AM, Alex Williamson wrote: > > On Mon, 30 Mar 2020 22:20:42 +0530 > > Kirti Wankhede <kwankhede@nvidia.com> wrote: > > > >> DMA mapped pages, including those pinned by mdev vendor drivers, might > >> get unpinned and unmapped while migration is active and device is still > >> running. For example, in pre-copy phase while guest driver could access > >> those pages, host device or vendor driver can dirty these mapped pages. > >> Such pages should be marked dirty so as to maintain memory consistency > >> for a user making use of dirty page tracking. > >> > >> To get bitmap during unmap, user should allocate memory for bitmap, set > >> size of allocated memory, set page size to be considered for bitmap and > >> set flag VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP. > >> > >> Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com> > >> Reviewed-by: Neo Jia <cjia@nvidia.com> > >> --- > >> drivers/vfio/vfio_iommu_type1.c | 55 ++++++++++++++++++++++++++++++++++++++--- > >> include/uapi/linux/vfio.h | 10 ++++++++ > >> 2 files changed, 61 insertions(+), 4 deletions(-) > >> > >> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c > >> index 5efebc2b60e1..266550bd7307 100644 > >> --- a/drivers/vfio/vfio_iommu_type1.c > >> +++ b/drivers/vfio/vfio_iommu_type1.c > >> @@ -983,7 +983,8 @@ static int verify_bitmap_size(uint64_t npages, uint64_t bitmap_size) > >> } > >> > >> static int vfio_dma_do_unmap(struct vfio_iommu *iommu, > >> - struct vfio_iommu_type1_dma_unmap *unmap) > >> + struct vfio_iommu_type1_dma_unmap *unmap, > >> + struct vfio_bitmap *bitmap) > >> { > >> uint64_t mask; > >> struct vfio_dma *dma, *dma_last = NULL; > >> @@ -1034,6 +1035,10 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu, > >> * will be returned if these conditions are not met. The v2 interface > >> * will only return success and a size of zero if there were no > >> * mappings within the range. > >> + * > >> + * When VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP flag is set, unmap request > >> + * must be for single mapping. Multiple mappings with this flag set is > >> + * not supported. > >> */ > >> if (iommu->v2) { > >> dma = vfio_find_dma(iommu, unmap->iova, 1); > >> @@ -1041,6 +1046,14 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu, > >> ret = -EINVAL; > >> goto unlock; > >> } > >> + > >> + if ((unmap->flags & VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP) && > >> + dma && > >> + (dma->iova != unmap->iova || dma->size != unmap->size)) { > > > > > > I think your intention was to return error if the user asked for the > > dirty bitmap and the requested unmap range doesn't exactly match the > > vfio_dma. Not finding a vfio_dma should therefore also be an error. > > For example, if we had a single mapping at {0x1000-0x1fff} and the user > > unmapped with dirty bitmap {0x0-0x2fff}, that should return an error, > > but it's not caught by the above because there is no vfio_dma @0x0. > > Therefore I think you want: > > > > ((unmap->flags & VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP) && > > (!dma || dma->iova != unmap->iova || dma->size != unmap->size)) > > > > Right? Thanks, > > > > > Yes, updating check. > > Is !dma here also error case when VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP > flag is not set? No it's not. > DMA_UNMAP ioctl returns how much was unmapped, from user space > perspective this would be from start of range (unmap->iova), right? It's the actual amount of memory that was unmapped within the provided range, without getting the dirty bitmap the range doesn't need to start or end at a vfio_dma, it just cannot bisect a vfio_dma. Thanks, Alex
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c index 5efebc2b60e1..266550bd7307 100644 --- a/drivers/vfio/vfio_iommu_type1.c +++ b/drivers/vfio/vfio_iommu_type1.c @@ -983,7 +983,8 @@ static int verify_bitmap_size(uint64_t npages, uint64_t bitmap_size) } static int vfio_dma_do_unmap(struct vfio_iommu *iommu, - struct vfio_iommu_type1_dma_unmap *unmap) + struct vfio_iommu_type1_dma_unmap *unmap, + struct vfio_bitmap *bitmap) { uint64_t mask; struct vfio_dma *dma, *dma_last = NULL; @@ -1034,6 +1035,10 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu, * will be returned if these conditions are not met. The v2 interface * will only return success and a size of zero if there were no * mappings within the range. + * + * When VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP flag is set, unmap request + * must be for single mapping. Multiple mappings with this flag set is + * not supported. */ if (iommu->v2) { dma = vfio_find_dma(iommu, unmap->iova, 1); @@ -1041,6 +1046,14 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu, ret = -EINVAL; goto unlock; } + + if ((unmap->flags & VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP) && + dma && + (dma->iova != unmap->iova || dma->size != unmap->size)) { + ret = -EINVAL; + goto unlock; + } + dma = vfio_find_dma(iommu, unmap->iova + unmap->size - 1, 0); if (dma && dma->iova + dma->size != unmap->iova + unmap->size) { ret = -EINVAL; @@ -1058,6 +1071,11 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu, if (dma->task->mm != current->mm) break; + if ((unmap->flags & VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP) && + iommu->dirty_page_tracking) + vfio_iova_dirty_bitmap(iommu, dma->iova, dma->size, + bitmap->pgsize, bitmap->data); + if (!RB_EMPTY_ROOT(&dma->pfn_list)) { struct vfio_iommu_type1_dma_unmap nb_unmap; @@ -2419,17 +2437,46 @@ static long vfio_iommu_type1_ioctl(void *iommu_data, } else if (cmd == VFIO_IOMMU_UNMAP_DMA) { struct vfio_iommu_type1_dma_unmap unmap; - long ret; + struct vfio_bitmap bitmap = { 0 }; + int ret; minsz = offsetofend(struct vfio_iommu_type1_dma_unmap, size); if (copy_from_user(&unmap, (void __user *)arg, minsz)) return -EFAULT; - if (unmap.argsz < minsz || unmap.flags) + if (unmap.argsz < minsz || + unmap.flags & ~VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP) return -EINVAL; - ret = vfio_dma_do_unmap(iommu, &unmap); + if (unmap.flags & VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP) { + unsigned long pgshift; + size_t iommu_pgsize = + (size_t)1 << __ffs(vfio_pgsize_bitmap(iommu)); + + if (unmap.argsz < (minsz + sizeof(bitmap))) + return -EINVAL; + + if (copy_from_user(&bitmap, + (void __user *)(arg + minsz), + sizeof(bitmap))) + return -EFAULT; + + /* allow only min supported pgsize */ + if (bitmap.pgsize != iommu_pgsize) + return -EINVAL; + if (!access_ok((void __user *)bitmap.data, bitmap.size)) + return -EINVAL; + + pgshift = __ffs(bitmap.pgsize); + ret = verify_bitmap_size(unmap.size >> pgshift, + bitmap.size); + if (ret) + return ret; + + } + + ret = vfio_dma_do_unmap(iommu, &unmap, &bitmap); if (ret) return ret; diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h index 5f359c63f5ef..e3cbf8b78623 100644 --- a/include/uapi/linux/vfio.h +++ b/include/uapi/linux/vfio.h @@ -1048,12 +1048,22 @@ struct vfio_bitmap { * field. No guarantee is made to the user that arbitrary unmaps of iova * or size different from those used in the original mapping call will * succeed. + * VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP should be set to get dirty bitmap + * before unmapping IO virtual addresses. When this flag is set, user must + * provide data[] as structure vfio_bitmap. User must allocate memory to get + * bitmap and must set size of allocated memory in vfio_bitmap.size field. + * A bit in bitmap represents one page of user provided page size in 'pgsize', + * consecutively starting from iova offset. Bit set indicates page at that + * offset from iova is dirty. Bitmap of pages in the range of unmapped size is + * returned in vfio_bitmap.data */ struct vfio_iommu_type1_dma_unmap { __u32 argsz; __u32 flags; +#define VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP (1 << 0) __u64 iova; /* IO virtual address */ __u64 size; /* Size of mapping (bytes) */ + __u8 data[]; }; #define VFIO_IOMMU_UNMAP_DMA _IO(VFIO_TYPE, VFIO_BASE + 14)