[PULL 09/10] vfio-ccw: Wire up the CRW irq and CRW region

Cornelia Huck
2020-05-25T09:42:02Z

From: Farhan Ali <alifm@linux.ibm.com>

Use the IRQ to notify userspace that there is a CRW
pending in the region, related to path-availability
changes on the passthrough subchannel.

Signed-off-by: Farhan Ali <alifm@linux.ibm.com>
Signed-off-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Message-Id: <20200505122745.53208-8-farman@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
---
drivers/s390/cio/vfio_ccw_chp.c | 17 ++++++++++
drivers/s390/cio/vfio_ccw_drv.c | 49 +++++++++++++++++++++++++++++
drivers/s390/cio/vfio_ccw_private.h | 8 +++++
3 files changed, 74 insertions(+)

diff --git a/drivers/s390/cio/vfio_ccw_chp.c b/drivers/s390/cio/vfio_ccw_chp.c
index 37ea344a4d72..876f6ade51cc 100644
--- a/drivers/s390/cio/vfio_ccw_chp.c
+++ b/drivers/s390/cio/vfio_ccw_chp.c
@@ -82,14 +82,24 @@ static ssize_t vfio_ccw_crw_region_read(struct vfio_ccw_private *private,
unsigned int i = VFIO_CCW_OFFSET_TO_INDEX(*ppos) - VFIO_CCW_NUM_REGIONS;
loff_t pos = *ppos & VFIO_CCW_OFFSET_MASK;
struct ccw_crw_region *region;
+ struct vfio_ccw_crw *crw;
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);
region = private->region[i].data;

+ if (crw)
+ memcpy(&region->crw, &crw->crw, sizeof(region->crw));
+
if (copy_to_user(buf, (void *)region + pos, count))
ret = -EFAULT;
else
@@ -98,6 +108,13 @@ static ssize_t vfio_ccw_crw_region_read(struct vfio_ccw_private *private,
region->crw = 0;

mutex_unlock(&private->io_mutex);
+
+ kfree(crw);
+
+ /* Notify the guest if more CRWs are on our queue */
+ if (!list_empty(&private->crw) && private->crw_trigger)
+ eventfd_signal(private->crw_trigger, 1);
+
return ret;
}

diff --git a/drivers/s390/cio/vfio_ccw_drv.c b/drivers/s390/cio/vfio_ccw_drv.c
index e4deae6fd525..9144360851ed 100644
--- a/drivers/s390/cio/vfio_ccw_drv.c
+++ b/drivers/s390/cio/vfio_ccw_drv.c
@@ -108,6 +108,16 @@ static void vfio_ccw_sch_io_todo(struct work_struct *work)
eventfd_signal(private->io_trigger, 1);
}

+static void vfio_ccw_crw_todo(struct work_struct *work)
+{
+ struct vfio_ccw_private *private;
+
+ private = container_of(work, struct vfio_ccw_private, crw_work);
+
+ if (!list_empty(&private->crw) && private->crw_trigger)
+ eventfd_signal(private->crw_trigger, 1);
+}
+
/*
* Css driver callbacks
*/
@@ -186,7 +196,9 @@ static int vfio_ccw_sch_probe(struct subchannel *sch)
if (ret)
goto out_free;

+ INIT_LIST_HEAD(&private->crw);
INIT_WORK(&private->io_work, vfio_ccw_sch_io_todo);
+ INIT_WORK(&private->crw_work, vfio_ccw_crw_todo);
atomic_set(&private->avail, 1);
private->state = VFIO_CCW_STATE_STANDBY;

@@ -217,9 +229,15 @@ static int vfio_ccw_sch_probe(struct subchannel *sch)
static int vfio_ccw_sch_remove(struct subchannel *sch)
{
struct vfio_ccw_private *private = dev_get_drvdata(&sch->dev);
+ struct vfio_ccw_crw *crw, *temp;

vfio_ccw_sch_quiesce(sch);

+ list_for_each_entry_safe(crw, temp, &private->crw, next) {
+ list_del(&crw->next);
+ kfree(crw);
+ }
+
vfio_ccw_mdev_unreg(sch);

dev_set_drvdata(&sch->dev, NULL);
@@ -281,6 +299,33 @@ static int vfio_ccw_sch_event(struct subchannel *sch, int process)
return rc;
}

+static void vfio_ccw_queue_crw(struct vfio_ccw_private *private,
+ unsigned int rsc,
+ unsigned int erc,
+ unsigned int rsid)
+{
+ struct vfio_ccw_crw *crw;
+
+ /*
+ * If unable to allocate a CRW, just drop the event and
+ * carry on. The guest will either see a later one or
+ * learn when it issues its own store subchannel.
+ */
+ crw = kzalloc(sizeof(*crw), GFP_ATOMIC);
+ if (!crw)
+ return;
+
+ /*
+ * Build the CRW based on the inputs given to us.
+ */
+ crw->crw.rsc = rsc;
+ crw->crw.erc = erc;
+ crw->crw.rsid = rsid;
+
+ list_add_tail(&crw->next, &private->crw);
+ queue_work(vfio_ccw_work_q, &private->crw_work);
+}
+
static int vfio_ccw_chp_event(struct subchannel *sch,
struct chp_link *link, int event)
{
@@ -311,6 +356,8 @@ static int vfio_ccw_chp_event(struct subchannel *sch,
/* Path is gone */
if (sch->schib.pmcw.lpum & mask)
cio_cancel_halt_clear(sch, &retry);
+ vfio_ccw_queue_crw(private, CRW_RSC_CPATH, CRW_ERC_PERRN,
+ link->chpid.id);
break;
case CHP_VARY_ON:
/* Path logically turned on */
@@ -320,6 +367,8 @@ static int vfio_ccw_chp_event(struct subchannel *sch,
case CHP_ONLINE:
/* Path became available */
sch->lpm |= mask & sch->opm;
+ vfio_ccw_queue_crw(private, CRW_RSC_CPATH, CRW_ERC_INIT,
+ link->chpid.id);
break;
}

diff --git a/drivers/s390/cio/vfio_ccw_private.h b/drivers/s390/cio/vfio_ccw_private.h
index 97131b4df0b9..8723156b29ea 100644
--- a/drivers/s390/cio/vfio_ccw_private.h
+++ b/drivers/s390/cio/vfio_ccw_private.h
@@ -17,6 +17,7 @@
#include <linux/eventfd.h>
#include <linux/workqueue.h>
#include <linux/vfio_ccw.h>
+#include <asm/crw.h>
#include <asm/debug.h>

#include "css.h"
@@ -59,6 +60,11 @@ int vfio_ccw_register_async_dev_regions(struct vfio_ccw_private *private);
int vfio_ccw_register_schib_dev_regions(struct vfio_ccw_private *private);
int vfio_ccw_register_crw_dev_regions(struct vfio_ccw_private *private);

+struct vfio_ccw_crw {
+ struct list_head next;
+ struct crw crw;
+};
+
/**
* struct vfio_ccw_private
* @sch: pointer to the subchannel
@@ -98,10 +104,12 @@ struct vfio_ccw_private {
struct channel_program cp;
struct irb irb;
union scsw scsw;
+ struct list_head crw;

struct eventfd_ctx *io_trigger;
struct eventfd_ctx *crw_trigger;
struct work_struct io_work;
+ struct work_struct crw_work;
} __aligned(8);

extern int vfio_ccw_mdev_reg(struct subchannel *sch);
--
2.25.4