It was suggested [1] that we replace the old copy_from_iova() routine (which pins a page, does a memcpy, and unpins the page) with the newer vfio_dma_rw() interface. This has a modest improvement in the overall time spent through the fsm_io_request() path, and simplifies some of the code to boot. [1] https://lore.kernel.org/r/20220706170553.GK693670@xxxxxxxxxx/ Suggested-by: Jason Gunthorpe <jgg@xxxxxxxxxx> Signed-off-by: Eric Farman <farman@xxxxxxxxxxxxx> --- drivers/s390/cio/vfio_ccw_cp.c | 56 +++------------------------------- 1 file changed, 5 insertions(+), 51 deletions(-) diff --git a/drivers/s390/cio/vfio_ccw_cp.c b/drivers/s390/cio/vfio_ccw_cp.c index 3a11132b1685..1eacbb8dc860 100644 --- a/drivers/s390/cio/vfio_ccw_cp.c +++ b/drivers/s390/cio/vfio_ccw_cp.c @@ -228,51 +228,6 @@ static void convert_ccw0_to_ccw1(struct ccw1 *source, unsigned long len) } } -/* - * Within the domain (@vdev), copy @n bytes from a guest physical - * address (@iova) to a host physical address (@to). - */ -static long copy_from_iova(struct vfio_device *vdev, void *to, u64 iova, - unsigned long n) -{ - struct page_array pa = {0}; - int i, ret; - unsigned long l, m; - - ret = page_array_alloc(&pa, iova, n); - if (ret < 0) - return ret; - - ret = page_array_pin(&pa, vdev); - if (ret < 0) { - page_array_unpin_free(&pa, vdev); - return ret; - } - - l = n; - for (i = 0; i < pa.pa_nr; i++) { - void *from = kmap_local_page(pa.pa_page[i]); - - m = PAGE_SIZE; - if (i == 0) { - from += iova & (PAGE_SIZE - 1); - m -= iova & (PAGE_SIZE - 1); - } - - m = min(l, m); - memcpy(to + (n - l), from, m); - kunmap_local(from); - - l -= m; - if (l == 0) - break; - } - - page_array_unpin_free(&pa, vdev); - - return l; -} - /* * Helpers to operate ccwchain. */ @@ -471,10 +426,9 @@ static int ccwchain_handle_ccw(u32 cda, struct channel_program *cp) int len, ret; /* Copy 2K (the most we support today) of possible CCWs */ - len = copy_from_iova(vdev, cp->guest_cp, cda, - CCWCHAIN_LEN_MAX * sizeof(struct ccw1)); - if (len) - return len; + ret = vfio_dma_rw(vdev, cda, cp->guest_cp, CCWCHAIN_LEN_MAX * sizeof(struct ccw1), false); + if (ret) + return ret; /* Convert any Format-0 CCWs to Format-1 */ if (!cp->orb.cmd.fmt) @@ -572,7 +526,7 @@ static int ccwchain_fetch_direct(struct ccwchain *chain, if (ccw_is_idal(ccw)) { /* Read first IDAW to see if it's 4K-aligned or not. */ /* All subsequent IDAws will be 4K-aligned. */ - ret = copy_from_iova(vdev, &iova, ccw->cda, sizeof(iova)); + ret = vfio_dma_rw(vdev, ccw->cda, &iova, sizeof(iova), false); if (ret) return ret; } else { @@ -601,7 +555,7 @@ static int ccwchain_fetch_direct(struct ccwchain *chain, if (ccw_is_idal(ccw)) { /* Copy guest IDAL into host IDAL */ - ret = copy_from_iova(vdev, idaws, ccw->cda, idal_len); + ret = vfio_dma_rw(vdev, ccw->cda, idaws, idal_len, false); if (ret) goto out_unpin; -- 2.34.1
