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vfio/ccw: replace copy_from_iova with vfio_dma_rw 

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@nvidia.com/

Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
This commit is contained in:
Eric Farman 2022-07-07 17:30:26 +02:00 committed by Heiko Carstens
parent 254cb663c2
commit c5e8083f95
1 changed files with 5 additions and 51 deletions
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56
drivers/s390/cio/vfio_ccw_cp.c
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@ -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;