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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: Kirti Wankhede <kwankhede@nvidia.com>
Suggested-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Kirti Wankhede <kwankhede@nvidia.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
This commit is contained in:
Alex Williamson 2017-04-16 15:57:18 -06:00
parent 0cfef2b741
commit 80dbe1fbaf
1 changed files with 8 additions and 27 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

35
drivers/vfio/vfio_iommu_type1.c
View File

@ -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) {