From: Steve Sistare steven.sistare@oracle.com
commit 90fdd158a695d70403163f9a0e4efc5b20f3fd3e upstream.
When a vfio container is preserved across exec or fork-exec, the new task's mm has a locked_vm count of 0. After a dma vaddr is updated using VFIO_DMA_MAP_FLAG_VADDR, locked_vm remains 0, and the pinned memory does not count against the task's RLIMIT_MEMLOCK.
To restore the correct locked_vm count, when VFIO_DMA_MAP_FLAG_VADDR is used and the dma's mm has changed, add the dma's locked_vm count to the new mm->locked_vm, subject to the rlimit, and subtract it from the old mm->locked_vm.
Fixes: c3cbab24db38 ("vfio/type1: implement interfaces to update vaddr") Cc: stable@vger.kernel.org Signed-off-by: Steve Sistare steven.sistare@oracle.com Reviewed-by: Kevin Tian kevin.tian@intel.com Reviewed-by: Jason Gunthorpe jgg@nvidia.com Link: https://lore.kernel.org/r/1675184289-267876-5-git-send-email-steven.sistare@... Signed-off-by: Alex Williamson alex.williamson@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/vfio/vfio_iommu_type1.c | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+)
--- a/drivers/vfio/vfio_iommu_type1.c +++ b/drivers/vfio/vfio_iommu_type1.c @@ -1591,6 +1591,38 @@ static bool vfio_iommu_iova_dma_valid(st return list_empty(iova); }
+static int vfio_change_dma_owner(struct vfio_dma *dma) +{ + struct task_struct *task = current->group_leader; + struct mm_struct *mm = current->mm; + long npage = dma->locked_vm; + bool lock_cap; + int ret; + + if (mm == dma->mm) + return 0; + + lock_cap = capable(CAP_IPC_LOCK); + ret = mm_lock_acct(task, mm, lock_cap, npage); + if (ret) + return ret; + + if (mmget_not_zero(dma->mm)) { + mm_lock_acct(dma->task, dma->mm, dma->lock_cap, -npage); + mmput(dma->mm); + } + + if (dma->task != task) { + put_task_struct(dma->task); + dma->task = get_task_struct(task); + } + mmdrop(dma->mm); + dma->mm = mm; + mmgrab(dma->mm); + dma->lock_cap = lock_cap; + return 0; +} + static int vfio_dma_do_map(struct vfio_iommu *iommu, struct vfio_iommu_type1_dma_map *map) { @@ -1640,6 +1672,9 @@ static int vfio_dma_do_map(struct vfio_i dma->size != size) { ret = -EINVAL; } else { + ret = vfio_change_dma_owner(dma); + if (ret) + goto out_unlock; dma->vaddr = vaddr; dma->vaddr_invalid = false; iommu->vaddr_invalid_count--;