| Message ID | 1671568765-297322-5-git-send-email-steven.sistare@oracle.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | fixes for virtual address update | expand |
On Tue, Dec 20, 2022 at 12:39:22PM -0800, Steve Sistare wrote: > 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. > > 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> > --- > drivers/vfio/vfio_iommu_type1.c | 32 ++++++++++++++++++++++++++++++++ > 1 file changed, 32 insertions(+) But you should subtract it from the old one as well? Jason
On 1/3/2023 10:22 AM, Jason Gunthorpe wrote: > On Tue, Dec 20, 2022 at 12:39:22PM -0800, Steve Sistare wrote: >> 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. >> >> 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> >> --- >> drivers/vfio/vfio_iommu_type1.c | 32 ++++++++++++++++++++++++++++++++ >> 1 file changed, 32 insertions(+) > > But you should subtract it from the old one as well? Yes, as implemented. I'll add that to the commit message. - Steve
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c index 588d690..1036736 100644 --- a/drivers/vfio/vfio_iommu_type1.c +++ b/drivers/vfio/vfio_iommu_type1.c @@ -1590,6 +1590,35 @@ static bool vfio_iommu_iova_dma_valid(struct vfio_iommu *iommu, return list_empty(iova); } +static int vfio_change_dma_owner(struct vfio_dma *dma) +{ + int ret = 0; + struct task_struct *task = current->group_leader; + struct mm_struct *mm = current->mm; + + if (mm != dma->mm) { + long npage = dma->locked_vm; + bool lock_cap = capable(CAP_IPC_LOCK); + + ret = mm_lock_acct(task, mm, lock_cap, npage, false); + if (ret) + return ret; + + mm_lock_acct(dma->task, dma->mm, dma->lock_cap, -npage, true); + + 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 ret; +} + static int vfio_dma_do_map(struct vfio_iommu *iommu, struct vfio_iommu_type1_dma_map *map) { @@ -1639,6 +1668,9 @@ static int vfio_dma_do_map(struct vfio_iommu *iommu, 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--;
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. 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> --- drivers/vfio/vfio_iommu_type1.c | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+)