vfio-ccw: Wire up the CRW irq and CRW region

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>

diff --git a/drivers/s390/cio/vfio_ccw_chp.c b/drivers/s390/cio/vfio_ccw_chp.c
index 37ea344a4d729c07b27f80e71d0740102fac990f..876f6ade51cc9966124881d64d2cbc04bbee16dd 100644 (file)
--- 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 e4deae6fd5256c3b53fe26a60ceb7606ef600f7e..9144360851ed4014fea7239ec4880f9c3cea3837 100644 (file)
--- 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 @@ out_free:
 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 @@ out_unlock:
        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 97131b4df0b95b6842dca7897f3aa37cf6d0b813..8723156b29eac64dba9ca3392041f59757cf3034 100644 (file)
--- 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);