This driver is the only caller of vfio_pin/unpin_pages that might pass in a non-contiguous PFN list, but in many cases it has a contiguous PFN list to process. So letting VFIO API handle a non-contiguous PFN list is actually counterproductive.
Add a pair of simple loops to pass in contiguous PFNs only, to have an efficient implementation in VFIO.
Signed-off-by: Nicolin Chen nicolinc@nvidia.com --- drivers/s390/cio/vfio_ccw_cp.c | 68 +++++++++++++++++++++++++++------- 1 file changed, 54 insertions(+), 14 deletions(-)
diff --git a/drivers/s390/cio/vfio_ccw_cp.c b/drivers/s390/cio/vfio_ccw_cp.c index 0c2be9421ab7..4659c2e35877 100644 --- a/drivers/s390/cio/vfio_ccw_cp.c +++ b/drivers/s390/cio/vfio_ccw_cp.c @@ -90,6 +90,37 @@ static int pfn_array_alloc(struct pfn_array *pa, u64 iova, unsigned int len) return 0; }
+/* + * pfn_array_unpin() - Unpin user pages in memory + * @pa: pfn_array on which to perform the operation + * @vdev: the vfio device to perform the operation + * @pa_nr: number of user pages to unpin + * + * Only unpin if any pages were pinned to begin with, i.e. pa_nr > 0, + * otherwise only clear pa->pa_nr + */ +static void pfn_array_unpin(struct pfn_array *pa, + struct vfio_device *vdev, int pa_nr) +{ + int unpinned = 0, npage = 1; + + while (unpinned < pa_nr) { + unsigned long *first = &pa->pa_iova_pfn[unpinned]; + unsigned long *last = &first[npage]; + + if (unpinned + npage < pa_nr && *first + npage == *last) { + npage++; + continue; + } + + vfio_unpin_pages(vdev, first, npage); + unpinned += npage; + npage = 1; + } + + pa->pa_nr = 0; +} + /* * pfn_array_pin() - Pin user pages in memory * @pa: pfn_array on which to perform the operation @@ -101,34 +132,43 @@ static int pfn_array_alloc(struct pfn_array *pa, u64 iova, unsigned int len) */ static int pfn_array_pin(struct pfn_array *pa, struct vfio_device *vdev) { + int pinned = 0, npage = 1; int ret = 0;
- ret = vfio_pin_pages(vdev, pa->pa_iova_pfn, pa->pa_nr, - IOMMU_READ | IOMMU_WRITE, pa->pa_pfn); + while (pinned < pa->pa_nr) { + unsigned long *first = &pa->pa_iova_pfn[pinned]; + unsigned long *last = &first[npage];
- if (ret < 0) { - goto err_out; - } else if (ret > 0 && ret != pa->pa_nr) { - vfio_unpin_pages(vdev, pa->pa_iova_pfn, ret); - ret = -EINVAL; - goto err_out; + if (pinned + npage < pa->pa_nr && *first + npage == *last) { + npage++; + continue; + } + + ret = vfio_pin_pages(vdev, first, npage, + IOMMU_READ | IOMMU_WRITE, + &pa->pa_pfn[pinned]); + if (ret < 0) { + goto err_out; + } else if (ret > 0 && ret != npage) { + pinned += ret; + ret = -EINVAL; + goto err_out; + } + pinned += npage; + npage = 1; }
return ret;
err_out: - pa->pa_nr = 0; - + pfn_array_unpin(pa, vdev, pinned); return ret; }
/* Unpin the pages before releasing the memory. */ static void pfn_array_unpin_free(struct pfn_array *pa, struct vfio_device *vdev) { - /* Only unpin if any pages were pinned to begin with */ - if (pa->pa_nr) - vfio_unpin_pages(vdev, pa->pa_iova_pfn, pa->pa_nr); - pa->pa_nr = 0; + pfn_array_unpin(pa, vdev, pa->pa_nr); kfree(pa->pa_iova_pfn); }