[PATCH v2 13/16] vfio/ccw: allocate/populate the guest idal

Eric Farman
2022-12-20T17:10:53Z

Today, we allocate memory for a list of IDAWs, and if the CCW
being processed contains an IDAL we read that data from the guest
into that space. We then copy each IDAW into the pa_iova array,
or fabricate that pa_iova array with a list of addresses based
on a direct-addressed CCW.

Combine the reading of the guest IDAL with the creation of a
pseudo-IDAL for direct-addressed CCWs, so that both CCW types
have a "guest" IDAL that can be populated straight into the
pa_iova array.

Signed-off-by: Eric Farman <farman@linux.ibm.com>
---
drivers/s390/cio/vfio_ccw_cp.c | 76 +++++++++++++++++++++++-----------
1 file changed, 52 insertions(+), 24 deletions(-)

diff --git a/drivers/s390/cio/vfio_ccw_cp.c b/drivers/s390/cio/vfio_ccw_cp.c
index 62a013a631d8..477835b5e5b8 100644
--- a/drivers/s390/cio/vfio_ccw_cp.c
+++ b/drivers/s390/cio/vfio_ccw_cp.c
@@ -192,11 +192,12 @@ static inline void page_array_idal_create_words(struct page_array *pa,
* idaw.
*/

- for (i = 0; i < pa->pa_nr; i++)
+ for (i = 0; i < pa->pa_nr; i++) {
idaws[i] = page_to_phys(pa->pa_page[i]);

- /* Adjust the first IDAW, since it may not start on a page boundary */
- idaws[0] += pa->pa_iova[0] & (PAGE_SIZE - 1);
+ /* Incorporate any offset from each starting address */
+ idaws[i] += pa->pa_iova[i] & (PAGE_SIZE - 1);
+ }
}

static void convert_ccw0_to_ccw1(struct ccw1 *source, unsigned long len)
@@ -496,6 +497,44 @@ static int ccwchain_fetch_tic(struct ccw1 *ccw,
return -EFAULT;
}

+static unsigned long *get_guest_idal(struct ccw1 *ccw,
+ struct channel_program *cp,
+ int idaw_nr)
+{
+ struct vfio_device *vdev =
+ &container_of(cp, struct vfio_ccw_private, cp)->vdev;
+ unsigned long *idaws;
+ int idal_len = idaw_nr * sizeof(*idaws);
+ int idaw_size = PAGE_SIZE;
+ int idaw_mask = ~(idaw_size - 1);
+ int i, ret;
+
+ idaws = kcalloc(idaw_nr, sizeof(*idaws), GFP_DMA | GFP_KERNEL);
+ if (!idaws)
+ return ERR_PTR(-ENOMEM);
+
+ if (ccw_is_idal(ccw)) {
+ /* Copy IDAL from guest */
+ ret = vfio_dma_rw(vdev, ccw->cda, idaws, idal_len, false);
+ if (ret) {
+ kfree(idaws);
+ return ERR_PTR(ret);
+ }
+ } else {
+ /* Fabricate an IDAL based off CCW data address */
+ if (cp->orb.cmd.c64) {
+ idaws[0] = ccw->cda;
+ for (i = 1; i < idaw_nr; i++)
+ idaws[i] = (idaws[i - 1] + idaw_size) & idaw_mask;
+ } else {
+ kfree(idaws);
+ return ERR_PTR(-EOPNOTSUPP);
+ }
+ }
+
+ return idaws;
+}
+
/*
* ccw_count_idaws() - Calculate the number of IDAWs needed to transfer
* a specified amount of data
@@ -557,7 +596,7 @@ static int ccwchain_fetch_ccw(struct ccw1 *ccw,
&container_of(cp, struct vfio_ccw_private, cp)->vdev;
unsigned long *idaws;
int ret;
- int idaw_nr, idal_len;
+ int idaw_nr;
int i;

/* Calculate size of IDAL */
@@ -565,12 +604,10 @@ static int ccwchain_fetch_ccw(struct ccw1 *ccw,
if (idaw_nr < 0)
return idaw_nr;

- idal_len = idaw_nr * sizeof(*idaws);
-
/* Allocate an IDAL from host storage */
- idaws = kcalloc(idaw_nr, sizeof(*idaws), GFP_DMA | GFP_KERNEL);
- if (!idaws) {
- ret = -ENOMEM;
+ idaws = get_guest_idal(ccw, cp, idaw_nr);
+ if (IS_ERR(idaws)) {
+ ret = PTR_ERR(idaws);
goto out_init;
}

@@ -584,22 +621,13 @@ static int ccwchain_fetch_ccw(struct ccw1 *ccw,
if (ret < 0)
goto out_free_idaws;

- if (ccw_is_idal(ccw)) {
- /* Copy guest IDAL into host IDAL */
- ret = vfio_dma_rw(vdev, ccw->cda, idaws, idal_len, false);
- if (ret)
- goto out_unpin;
-
- /*
- * Copy guest IDAWs into page_array, in case the memory they
- * occupy is not contiguous.
- */
- for (i = 0; i < idaw_nr; i++)
+ /*
+ * Copy guest IDAWs into page_array, in case the memory they
+ * occupy is not contiguous.
+ */
+ for (i = 0; i < idaw_nr; i++) {
+ if (cp->orb.cmd.c64)
pa->pa_iova[i] = idaws[i];
- } else {
- pa->pa_iova[0] = ccw->cda;
- for (i = 1; i < pa->pa_nr; i++)
- pa->pa_iova[i] = pa->pa_iova[i - 1] + PAGE_SIZE;
}

if (ccw_does_data_transfer(ccw)) {
--
2.34.1