On 01/30/2019 08:22 AM, Cornelia Huck wrote:
When we get a solicited interrupt, the start function may have
been cleared by a csch, but we still have a channel program
structure allocated. Make it safe to call the cp accessors in
any case, so we can call them unconditionally.
While at it, also make sure that functions called from other parts
of the code return gracefully if the channel program structure
has not been initialized (even though that is a bug in the caller).
Signed-off-by: Cornelia Huck <cohuck@xxxxxxxxxx>
---
drivers/s390/cio/vfio_ccw_cp.c | 20 +++++++++++++++++++-
drivers/s390/cio/vfio_ccw_cp.h | 2 ++
drivers/s390/cio/vfio_ccw_fsm.c | 5 +++++
3 files changed, 26 insertions(+), 1 deletion(-)
diff --git a/drivers/s390/cio/vfio_ccw_cp.c b/drivers/s390/cio/vfio_ccw_cp.c
index ba08fe137c2e..0bc0c38edda7 100644
--- a/drivers/s390/cio/vfio_ccw_cp.c
+++ b/drivers/s390/cio/vfio_ccw_cp.c
@@ -335,6 +335,7 @@ static void cp_unpin_free(struct channel_program *cp)
struct ccwchain *chain, *temp;
int i;
+ cp->initialized = false;
list_for_each_entry_safe(chain, temp, &cp->ccwchain_list, next) {
for (i = 0; i < chain->ch_len; i++) {
pfn_array_table_unpin_free(chain->ch_pat + i,
@@ -701,6 +702,8 @@ int cp_init(struct channel_program *cp, struct device *mdev, union orb *orb)
*/
cp->orb.cmd.c64 = 1;
+ cp->initialized = true;
+
Not seen in this hunk, but we call ccwchain_loop_tic() just prior to
this point. If that returns non-zero, we call cp_unpin_free()[1] (and
set initailized to false), and then fall through to here. So this is
going to set initialized to true, even though we're taking an error
path. :-(
[1] Wait, why is it calling cp_unpin_free()? Oh, I had proposed
squashing cp_free() and cp_unpin_free() back in November[2], got an r-b
from Pierre but haven't gotten back to tidy up the series for a v2.
Okay, I'll try to do that again soon. :-)
[2] https://patchwork.kernel.org/patch/10675261/
return ret;
}
@@ -715,7 +718,8 @@ int cp_init(struct channel_program *cp, struct device *mdev, union orb *orb)
*/
void cp_free(struct channel_program *cp)
{
- cp_unpin_free(cp);
+ if (cp->initialized)
+ cp_unpin_free(cp);
}
/**
@@ -760,6 +764,10 @@ int cp_prefetch(struct channel_program *cp)
struct ccwchain *chain;
int len, idx, ret;
+ /* this is an error in the caller */
+ if (!cp || !cp->initialized)
+ return -EINVAL;
+
list_for_each_entry(chain, &cp->ccwchain_list, next) {
len = chain->ch_len;
for (idx = 0; idx < len; idx++) {
@@ -795,6 +803,10 @@ union orb *cp_get_orb(struct channel_program *cp, u32 intparm, u8 lpm)
struct ccwchain *chain;
struct ccw1 *cpa;
+ /* this is an error in the caller */
+ if (!cp || !cp->initialized)
+ return NULL;
+
orb = &cp->orb;
orb->cmd.intparm = intparm;
@@ -831,6 +843,9 @@ void cp_update_scsw(struct channel_program *cp, union scsw *scsw)
u32 cpa = scsw->cmd.cpa;
u32 ccw_head, ccw_tail;
+ if (!cp->initialized)
+ return;
+
/*
* LATER:
* For now, only update the cmd.cpa part. We may need to deal with
@@ -869,6 +884,9 @@ bool cp_iova_pinned(struct channel_program *cp, u64 iova)
struct ccwchain *chain;
int i;
+ if (!cp->initialized)
So, two of the checks added above look for a nonzero cp pointer prior to
checking initialized, while two don't. I guess cp can't be NULL, since
it's embedded in the private struct directly and that's only free'd when
we do vfio_ccw_sch_remove() ... But I guess some consistency in how we
look would be nice.
+ return false;
+
list_for_each_entry(chain, &cp->ccwchain_list, next) {
for (i = 0; i < chain->ch_len; i++)
if (pfn_array_table_iova_pinned(chain->ch_pat + i,
diff --git a/drivers/s390/cio/vfio_ccw_cp.h b/drivers/s390/cio/vfio_ccw_cp.h
index a4b74fb1aa57..3c20cd208da5 100644
--- a/drivers/s390/cio/vfio_ccw_cp.h
+++ b/drivers/s390/cio/vfio_ccw_cp.h
@@ -21,6 +21,7 @@
* @ccwchain_list: list head of ccwchains
* @orb: orb for the currently processed ssch request
* @mdev: the mediated device to perform page pinning/unpinning
+ * @initialized: whether this instance is actually initialized
*
* @ccwchain_list is the head of a ccwchain list, that contents the
* translated result of the guest channel program that pointed out by
@@ -30,6 +31,7 @@ struct channel_program {
struct list_head ccwchain_list;
union orb orb;
struct device *mdev;
+ bool initialized;
};
extern int cp_init(struct channel_program *cp, struct device *mdev,
diff --git a/drivers/s390/cio/vfio_ccw_fsm.c b/drivers/s390/cio/vfio_ccw_fsm.c
index cab17865aafe..e7c9877c9f1e 100644
--- a/drivers/s390/cio/vfio_ccw_fsm.c
+++ b/drivers/s390/cio/vfio_ccw_fsm.c
@@ -31,6 +31,10 @@ static int fsm_io_helper(struct vfio_ccw_private *private)
private->state = VFIO_CCW_STATE_BUSY;
orb = cp_get_orb(&private->cp, (u32)(addr_t)sch, sch->lpm);
+ if (!orb) {
+ ret = -EIO;
+ goto out;
+ }
/* Issue "Start Subchannel" */
ccode = ssch(sch->schid, orb);
@@ -64,6 +68,7 @@ static int fsm_io_helper(struct vfio_ccw_private *private)
default:
ret = ccode;
}
+out:
spin_unlock_irqrestore(sch->lock, flags);
return ret;
}
