Unlike the channel_program struct, which covers synchronous I/O submissions and asynchronous interrupts, the CRW region relies exclusively on asynchronous events coming from hardware. Implement a lock to manage the list of those payloads, to ensure they are read cohesively. Fixes: 3f02cb2fd9d2 ("vfio-ccw: Wire up the CRW irq and CRW region") Cc: stable@vger.kernel.org Cc: Farhan Ali Reviewed-by: Matthew Rosato Signed-off-by: Eric Farman --- drivers/s390/cio/vfio_ccw_chp.c | 26 ++++++++++++++++---------- drivers/s390/cio/vfio_ccw_drv.c | 6 ++++++ drivers/s390/cio/vfio_ccw_ops.c | 4 ++++ drivers/s390/cio/vfio_ccw_private.h | 4 ++++ 4 files changed, 30 insertions(+), 10 deletions(-) diff --git a/drivers/s390/cio/vfio_ccw_chp.c b/drivers/s390/cio/vfio_ccw_chp.c index f3015132d4b5..7708eb4d6de0 100644 --- a/drivers/s390/cio/vfio_ccw_chp.c +++ b/drivers/s390/cio/vfio_ccw_chp.c @@ -93,17 +93,12 @@ static ssize_t vfio_ccw_crw_region_read(struct vfio_ccw_private *private, loff_t pos = *ppos & VFIO_CCW_OFFSET_MASK; struct ccw_crw_region *region; struct vfio_ccw_crw *crw; + unsigned long flags; int ret; if (pos + count > sizeof(*region)) return -EINVAL; - crw = list_first_entry_or_null(&private->crw, - struct vfio_ccw_crw, next); - - if (crw) - list_del(&crw->next); - mutex_lock(&private->io_mutex); if (i >= private->num_regions) { ret = -EINVAL; @@ -113,6 +108,16 @@ static ssize_t vfio_ccw_crw_region_read(struct vfio_ccw_private *private, i = array_index_nospec(i, private->num_regions); region = private->region[i].data; + spin_lock_irqsave(&private->crw_lock, flags); + crw = list_first_entry_or_null(&private->crw, + struct vfio_ccw_crw, next); + + if (crw) + list_del(&crw->next); + + /* Drop CRW lock while copying to userspace */ + spin_unlock_irqrestore(&private->crw_lock, flags); + if (crw) memcpy(®ion->crw, &crw->crw, sizeof(region->crw)); @@ -122,15 +127,16 @@ static ssize_t vfio_ccw_crw_region_read(struct vfio_ccw_private *private, ret = count; region->crw = 0; - -out: - mutex_unlock(&private->io_mutex); - kfree(crw); /* Notify the guest if more CRWs are on our queue */ + spin_lock_irqsave(&private->crw_lock, flags); if (!list_empty(&private->crw) && private->crw_trigger) eventfd_signal(private->crw_trigger); + spin_unlock_irqrestore(&private->crw_lock, flags); + +out: + mutex_unlock(&private->io_mutex); return ret; } diff --git a/drivers/s390/cio/vfio_ccw_drv.c b/drivers/s390/cio/vfio_ccw_drv.c index faf2de074a10..d7e93b9d491c 100644 --- a/drivers/s390/cio/vfio_ccw_drv.c +++ b/drivers/s390/cio/vfio_ccw_drv.c @@ -122,11 +122,14 @@ void vfio_ccw_sch_io_todo(struct work_struct *work) void vfio_ccw_crw_todo(struct work_struct *work) { struct vfio_ccw_private *private; + unsigned long flags; private = container_of(work, struct vfio_ccw_private, crw_work); + spin_lock_irqsave(&private->crw_lock, flags); if (!list_empty(&private->crw) && private->crw_trigger) eventfd_signal(private->crw_trigger); + spin_unlock_irqrestore(&private->crw_lock, flags); } /* @@ -279,6 +282,7 @@ static void vfio_ccw_queue_crw(struct vfio_ccw_private *private, unsigned int rsid) { struct vfio_ccw_crw *crw; + unsigned long flags; /* * If unable to allocate a CRW, just drop the event and @@ -296,7 +300,9 @@ static void vfio_ccw_queue_crw(struct vfio_ccw_private *private, crw->crw.erc = erc; crw->crw.rsid = rsid; + spin_lock_irqsave(&private->crw_lock, flags); list_add_tail(&crw->next, &private->crw); + spin_unlock_irqrestore(&private->crw_lock, flags); queue_work(vfio_ccw_work_q, &private->crw_work); } diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c index ddfcd2b4296f..2f28846fdf72 100644 --- a/drivers/s390/cio/vfio_ccw_ops.c +++ b/drivers/s390/cio/vfio_ccw_ops.c @@ -60,6 +60,7 @@ static int vfio_ccw_mdev_init_dev(struct vfio_device *vdev) INIT_LIST_HEAD(&private->crw); INIT_WORK(&private->io_work, vfio_ccw_sch_io_todo); INIT_WORK(&private->crw_work, vfio_ccw_crw_todo); + spin_lock_init(&private->crw_lock); private->cp.guest_cp = kzalloc_objs(struct ccw1, CCWCHAIN_LEN_MAX); if (!private->cp.guest_cp) @@ -137,11 +138,14 @@ static void vfio_ccw_mdev_release_dev(struct vfio_device *vdev) struct vfio_ccw_private *private = container_of(vdev, struct vfio_ccw_private, vdev); struct vfio_ccw_crw *crw, *temp; + unsigned long flags; + spin_lock_irqsave(&private->crw_lock, flags); list_for_each_entry_safe(crw, temp, &private->crw, next) { list_del(&crw->next); kfree(crw); } + spin_unlock_irqrestore(&private->crw_lock, flags); /* Should be empty, but just in case */ cancel_work_sync(&private->io_work); diff --git a/drivers/s390/cio/vfio_ccw_private.h b/drivers/s390/cio/vfio_ccw_private.h index ac5aaa78a74b..c23430e1a78e 100644 --- a/drivers/s390/cio/vfio_ccw_private.h +++ b/drivers/s390/cio/vfio_ccw_private.h @@ -98,6 +98,8 @@ struct vfio_ccw_parent { * @cp: channel program for the current I/O operation * @irb: irb info received from interrupt * @scsw: scsw info + * @crw_lock: serialization of CRW list information + * @crw: list of Channel Report Word elements * @io_trigger: eventfd ctx for signaling userspace I/O results * @crw_trigger: eventfd ctx for signaling userspace CRW information * @req_trigger: eventfd ctx for signaling userspace to return device @@ -121,6 +123,8 @@ struct vfio_ccw_private { struct irb irb; union scsw scsw; + + spinlock_t crw_lock; struct list_head crw; struct eventfd_ctx *io_trigger; -- 2.53.0