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vfio/type1: restore locked_vm 

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: c3cbab24db ("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@oracle.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
This commit is contained in:
Steve Sistare 2023-01-31 08:58:06 -08:00 committed by Alex Williamson
parent 18e292705b
commit 90fdd158a6
1 changed files with 35 additions and 0 deletions
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35
drivers/vfio/vfio_iommu_type1.c
View File

@ -1591,6 +1591,38 @@ 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)
{
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_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--;