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Commit 80dbe1fb authored by Alex Williamson's avatar Alex Williamson
Browse files

vfio/type1: Prune vfio_pin_page_external() 



With vfio_lock_acct() testing the locked memory limit under mmap_sem,
it's redundant to do it here for a single page.  We can also reorder
our tests such that we can avoid testing for reserved pages if we're
not doing accounting and let vfio_lock_acct() test the process
CAP_IPC_LOCK.  Finally, this function oddly returns 1 on success.
Update to return zero on success, -errno on error.  Since the function
only pins a single page, there's no need to return the number of pages
pinned.

N.B. vfio_pin_pages_remote() can pin a large contiguous range of pages
before calling vfio_lock_acct().  If we were to similarly remove the
extra test there, a user could temporarily pin far more pages than
they're allowed.

Suggested-by: default avatarKirti Wankhede <kwankhede@nvidia.com>
Suggested-by: default avatarEric Auger <eric.auger@redhat.com>
Reviewed-by: default avatarKirti Wankhede <kwankhede@nvidia.com>
Reviewed-by: default avatarPeter Xu <peterx@redhat.com>
Signed-off-by: default avatarAlex Williamson <alex.williamson@redhat.com>
parent 0cfef2b7

drivers/vfio/vfio_iommu_type1.c

+8 −27
Original line number Diff line number Diff line
@@ -482,43 +482,26 @@ static long vfio_unpin_pages_remote(struct vfio_dma *dma, dma_addr_t iova, 
static int vfio_pin_page_external(struct vfio_dma *dma, unsigned long vaddr,

				  unsigned long *pfn_base, bool do_accounting)

{

	unsigned long limit;

	bool lock_cap = has_capability(dma->task, CAP_IPC_LOCK);

	struct mm_struct *mm;

	int ret;

	bool rsvd;



	mm = get_task_mm(dma->task);

	if (!mm)

		return -ENODEV;



	ret = vaddr_get_pfn(mm, vaddr, dma->prot, pfn_base);

	if (ret)

		goto pin_page_exit;



	rsvd = is_invalid_reserved_pfn(*pfn_base);

	limit = task_rlimit(dma->task, RLIMIT_MEMLOCK) >> PAGE_SHIFT;



	if (!rsvd && !lock_cap && mm->locked_vm + 1 > limit) {

		put_pfn(*pfn_base, dma->prot);

		pr_warn("%s: Task %s (%d) RLIMIT_MEMLOCK (%ld) exceeded\n",

			__func__, dma->task->comm, task_pid_nr(dma->task),

			limit << PAGE_SHIFT);

		ret = -ENOMEM;

		goto pin_page_exit;

	}



	if (!rsvd && do_accounting) {

		ret = vfio_lock_acct(dma->task, 1, &lock_cap);

	if (!ret && do_accounting && !is_invalid_reserved_pfn(*pfn_base)) {

		ret = vfio_lock_acct(dma->task, 1, NULL);

		if (ret) {

			put_pfn(*pfn_base, dma->prot);

			goto pin_page_exit;

			if (ret == -ENOMEM)

				pr_warn("%s: Task %s (%d) RLIMIT_MEMLOCK "

					"(%ld) exceeded\n", __func__,

					dma->task->comm, task_pid_nr(dma->task),

					task_rlimit(dma->task, RLIMIT_MEMLOCK));

		}

	}



	ret = 1;



pin_page_exit:

	mmput(mm);

	return ret;

}
@@ -598,10 +581,8 @@ static int vfio_iommu_type1_pin_pages(void *iommu_data, 
		remote_vaddr = dma->vaddr + iova - dma->iova;

		ret = vfio_pin_page_external(dma, remote_vaddr, &phys_pfn[i],

					     do_accounting);

		if (ret <= 0) {

			WARN_ON(!ret);

		if (ret)

			goto pin_unwind;

		}



		ret = vfio_add_to_pfn_list(dma, iova, phys_pfn[i]);

		if (ret) {