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s390/vfio_ccw: Implement a crw lock

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commit 16b0798024 upstream.

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: 3f02cb2fd9 ("vfio-ccw: Wire up the CRW irq and CRW region")
Cc: stable@vger.kernel.org
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Reviewed-by: Farhan Ali <alifm@linux.ibm.com>
Signed-off-by: Eric Farman <farman@linux.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
[farman@linux.ibm.com: resolved merge conflict]
Signed-off-by: Eric Farman <farman@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Eric Farman
2026-08-27 14:29:45 +02:00
committed by Greg Kroah-Hartman
parent f0d189d95e
commit a3d60ae241
4 changed files with 30 additions and 10 deletions
Download Patch File Download Diff File Expand all files Collapse all files
drivers/s390/cio/vfio_ccw_chp.c
+16 -10
View File
@@ -93,18 +93,13 @@ 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;
mutex_lock(&private->io_mutex);
crw = list_first_entry_or_null(&private->crw,
struct vfio_ccw_crw, next);
if (crw)
list_del(&crw->next);
if (i >= private->num_regions) {
ret = -EINVAL;
goto out;
@@ -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(&region->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, 1);
spin_unlock_irqrestore(&private->crw_lock, flags);
out:
mutex_unlock(&private->io_mutex);
return ret;
}
drivers/s390/cio/vfio_ccw_drv.c
+6
View File
@@ -118,11 +118,14 @@ 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, 1);
spin_unlock_irqrestore(&private->crw_lock, flags);
}
void vfio_ccw_notoper_todo(struct work_struct *work)
@@ -286,6 +289,7 @@ 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
@@ -303,7 +307,9 @@ 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);
}
drivers/s390/cio/vfio_ccw_ops.c
+4
View File
@@ -55,6 +55,7 @@ static int vfio_ccw_mdev_init_dev(struct vfio_device *vdev)
INIT_WORK(&private->io_work, vfio_ccw_sch_io_todo);
INIT_WORK(&private->crw_work, vfio_ccw_crw_todo);
INIT_WORK(&private->notoper_work, vfio_ccw_notoper_todo);
spin_lock_init(&private->crw_lock);
private->cp.guest_cp = kcalloc(CCWCHAIN_LEN_MAX, sizeof(struct ccw1),
GFP_KERNEL);
@@ -132,6 +133,7 @@ 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;
/*
* Ensure these work items are fully drained, so none can
@@ -147,10 +149,12 @@ static void vfio_ccw_mdev_release_dev(struct vfio_device *vdev)
cancel_work_sync(&private->crw_work);
flush_work(&private->notoper_work);
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);
kmem_cache_free(vfio_ccw_crw_region, private->crw_region);
kmem_cache_free(vfio_ccw_schib_region, private->schib_region);
drivers/s390/cio/vfio_ccw_private.h
+4
View File
@@ -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
@@ -120,6 +122,8 @@ struct vfio_ccw_private {
struct channel_program cp;
struct irb irb;
union scsw scsw;
spinlock_t crw_lock;
struct list_head crw;
struct eventfd_ctx *io_trigger;