vfio-ccw: Introduce a new CRW region

This region provides a mechanism to pass a Channel Report Word
that affect vfio-ccw devices, and needs to be passed to the guest
for its awareness and/or processing.

The base driver (see crw_collect_info()) provides space for two
CRWs, as a subchannel event may have two CRWs chained together
(one for the ssid, one for the subchannel).  As vfio-ccw will
deal with everything at the subchannel level, provide space
for a single CRW to be transferred in one shot.

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: <20200505122745.53208-7-farman@linux.ibm.com>
[CH: added padding to ccw_crw_region]
Signed-off-by: Cornelia Huck <cohuck@redhat.com>

diff --git a/Documentation/s390/vfio-ccw.rst b/Documentation/s390/vfio-ccw.rst
index 32310df525bacf3350ee1e00f147d768293fc21c..8aad08a8b8a50384dba9c500efc82e4b1679fdf6 100644 (file)
--- a/Documentation/s390/vfio-ccw.rst
+++ b/Documentation/s390/vfio-ccw.rst
@@ -298,6 +298,26 @@ This region is exposed via region type VFIO_REGION_SUBTYPE_CCW_SCHIB.
 Reading this region triggers a STORE SUBCHANNEL to be issued to the
 associated hardware.
 
+vfio-ccw crw region
+---------------------
+
+The vfio-ccw crw region is used to return Channel Report Word (CRW)
+data to userspace::
+
+  struct ccw_crw_region {
+         __u32 crw;
+         __u32 pad;
+  } __packed;
+
+This region is exposed via region type VFIO_REGION_SUBTYPE_CCW_CRW.
+
+Reading this region returns a CRW if one that is relevant for this
+subchannel (e.g. one reporting changes in channel path state) is
+pending, or all zeroes if not. If multiple CRWs are pending (including
+possibly chained CRWs), reading this region again will return the next
+one, until no more CRWs are pending and zeroes are returned. This is
+similar to how STORE CHANNEL REPORT WORD works.
+
 vfio-ccw operation details
 --------------------------
 

diff --git a/drivers/s390/cio/vfio_ccw_chp.c b/drivers/s390/cio/vfio_ccw_chp.c
index 18f3b3e873a99ce7a219e65fe99415c90cb36c8c..37ea344a4d729c07b27f80e71d0740102fac990f 100644 (file)
--- a/drivers/s390/cio/vfio_ccw_chp.c
+++ b/drivers/s390/cio/vfio_ccw_chp.c
@@ -74,3 +74,58 @@ int vfio_ccw_register_schib_dev_regions(struct vfio_ccw_private *private)
                                            VFIO_REGION_INFO_FLAG_READ,
                                            private->schib_region);
 }
+
+static ssize_t vfio_ccw_crw_region_read(struct vfio_ccw_private *private,
+                                       char __user *buf, size_t count,
+                                       loff_t *ppos)
+{
+       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;
+       int ret;
+
+       if (pos + count > sizeof(*region))
+               return -EINVAL;
+
+       mutex_lock(&private->io_mutex);
+       region = private->region[i].data;
+
+       if (copy_to_user(buf, (void *)region + pos, count))
+               ret = -EFAULT;
+       else
+               ret = count;
+
+       region->crw = 0;
+
+       mutex_unlock(&private->io_mutex);
+       return ret;
+}
+
+static ssize_t vfio_ccw_crw_region_write(struct vfio_ccw_private *private,
+                                        const char __user *buf, size_t count,
+                                        loff_t *ppos)
+{
+       return -EINVAL;
+}
+
+static void vfio_ccw_crw_region_release(struct vfio_ccw_private *private,
+                                       struct vfio_ccw_region *region)
+{
+
+}
+
+const struct vfio_ccw_regops vfio_ccw_crw_region_ops = {
+       .read = vfio_ccw_crw_region_read,
+       .write = vfio_ccw_crw_region_write,
+       .release = vfio_ccw_crw_region_release,
+};
+
+int vfio_ccw_register_crw_dev_regions(struct vfio_ccw_private *private)
+{
+       return vfio_ccw_register_dev_region(private,
+                                           VFIO_REGION_SUBTYPE_CCW_CRW,
+                                           &vfio_ccw_crw_region_ops,
+                                           sizeof(struct ccw_crw_region),
+                                           VFIO_REGION_INFO_FLAG_READ,
+                                           private->crw_region);
+}

diff --git a/drivers/s390/cio/vfio_ccw_drv.c b/drivers/s390/cio/vfio_ccw_drv.c
index 7aeff42f370d70a21363668c634d089ee9874f6e..e4deae6fd5256c3b53fe26a60ceb7606ef600f7e 100644 (file)
--- a/drivers/s390/cio/vfio_ccw_drv.c
+++ b/drivers/s390/cio/vfio_ccw_drv.c
@@ -28,6 +28,7 @@ struct workqueue_struct *vfio_ccw_work_q;
 static struct kmem_cache *vfio_ccw_io_region;
 static struct kmem_cache *vfio_ccw_cmd_region;
 static struct kmem_cache *vfio_ccw_schib_region;
+static struct kmem_cache *vfio_ccw_crw_region;
 
 debug_info_t *vfio_ccw_debug_msg_id;
 debug_info_t *vfio_ccw_debug_trace_id;
@@ -120,6 +121,8 @@ static void vfio_ccw_sch_irq(struct subchannel *sch)
 
 static void vfio_ccw_free_regions(struct vfio_ccw_private *private)
 {
+       if (private->crw_region)
+               kmem_cache_free(vfio_ccw_crw_region, private->crw_region);
        if (private->schib_region)
                kmem_cache_free(vfio_ccw_schib_region, private->schib_region);
        if (private->cmd_region)
@@ -165,6 +168,12 @@ static int vfio_ccw_sch_probe(struct subchannel *sch)
        if (!private->schib_region)
                goto out_free;
 
+       private->crw_region = kmem_cache_zalloc(vfio_ccw_crw_region,
+                                               GFP_KERNEL | GFP_DMA);
+
+       if (!private->crw_region)
+               goto out_free;
+
        private->sch = sch;
        dev_set_drvdata(&sch->dev, private);
        mutex_init(&private->io_mutex);
@@ -366,6 +375,7 @@ static void vfio_ccw_debug_exit(void)
 
 static void vfio_ccw_destroy_regions(void)
 {
+       kmem_cache_destroy(vfio_ccw_crw_region);
        kmem_cache_destroy(vfio_ccw_schib_region);
        kmem_cache_destroy(vfio_ccw_cmd_region);
        kmem_cache_destroy(vfio_ccw_io_region);
@@ -413,6 +423,16 @@ static int __init vfio_ccw_sch_init(void)
                goto out_err;
        }
 
+       vfio_ccw_crw_region = kmem_cache_create_usercopy("vfio_ccw_crw_region",
+                                       sizeof(struct ccw_crw_region), 0,
+                                       SLAB_ACCOUNT, 0,
+                                       sizeof(struct ccw_crw_region), NULL);
+
+       if (!vfio_ccw_crw_region) {
+               ret = -ENOMEM;
+               goto out_err;
+       }
+
        isc_register(VFIO_CCW_ISC);
        ret = css_driver_register(&vfio_ccw_sch_driver);
        if (ret) {

diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
index c3a74ab7bb868ef8c4e90568be659bd36de63efa..8b3ed5b45277aca1f3083420cc532169f002715e 100644 (file)
--- a/drivers/s390/cio/vfio_ccw_ops.c
+++ b/drivers/s390/cio/vfio_ccw_ops.c
@@ -178,6 +178,10 @@ static int vfio_ccw_mdev_open(struct mdev_device *mdev)
        if (ret)
                goto out_unregister;
 
+       ret = vfio_ccw_register_crw_dev_regions(private);
+       if (ret)
+               goto out_unregister;
+
        return ret;
 
 out_unregister:
@@ -389,6 +393,7 @@ static int vfio_ccw_mdev_get_irq_info(struct vfio_irq_info *info)
 {
        switch (info->index) {
        case VFIO_CCW_IO_IRQ_INDEX:
+       case VFIO_CCW_CRW_IRQ_INDEX:
                info->count = 1;
                info->flags = VFIO_IRQ_INFO_EVENTFD;
                break;
@@ -416,6 +421,9 @@ static int vfio_ccw_mdev_set_irqs(struct mdev_device *mdev,
        case VFIO_CCW_IO_IRQ_INDEX:
                ctx = &private->io_trigger;
                break;
+       case VFIO_CCW_CRW_IRQ_INDEX:
+               ctx = &private->crw_trigger;
+               break;
        default:
                return -EINVAL;
        }

diff --git a/drivers/s390/cio/vfio_ccw_private.h b/drivers/s390/cio/vfio_ccw_private.h
index d6601a8adf137ff4a930b6fd50288837152aef1d..97131b4df0b95b6842dca7897f3aa37cf6d0b813 100644 (file)
--- a/drivers/s390/cio/vfio_ccw_private.h
+++ b/drivers/s390/cio/vfio_ccw_private.h
@@ -57,6 +57,7 @@ void vfio_ccw_unregister_dev_regions(struct vfio_ccw_private *private);
 
 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_private
@@ -71,6 +72,7 @@ int vfio_ccw_register_schib_dev_regions(struct vfio_ccw_private *private);
  * @region: additional regions for other subchannel operations
  * @cmd_region: MMIO region for asynchronous I/O commands other than START
  * @schib_region: MMIO region for SCHIB information
+ * @crw_region: MMIO region for getting channel report words
  * @num_regions: number of additional regions
  * @cp: channel program for the current I/O operation
  * @irb: irb info received from interrupt
@@ -90,6 +92,7 @@ struct vfio_ccw_private {
        struct vfio_ccw_region *region;
        struct ccw_cmd_region   *cmd_region;
        struct ccw_schib_region *schib_region;
+       struct ccw_crw_region   *crw_region;
        int num_regions;
 
        struct channel_program  cp;
@@ -97,6 +100,7 @@ struct vfio_ccw_private {
        union scsw              scsw;
 
        struct eventfd_ctx      *io_trigger;
+       struct eventfd_ctx      *crw_trigger;
        struct work_struct      io_work;
 } __aligned(8);
 

diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 7a1abbd889bd8d74c33ee48309e55f0dec759db5..907758cf6d606691474e3e65972edc8ef4e65985 100644 (file)
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -379,6 +379,7 @@ struct vfio_region_gfx_edid {
 /* sub-types for VFIO_REGION_TYPE_CCW */
 #define VFIO_REGION_SUBTYPE_CCW_ASYNC_CMD      (1)
 #define VFIO_REGION_SUBTYPE_CCW_SCHIB          (2)
+#define VFIO_REGION_SUBTYPE_CCW_CRW            (3)
 
 /*
  * The MSIX mappable capability informs that MSIX data of a BAR can be mmapped
@@ -578,6 +579,7 @@ enum {
 
 enum {
        VFIO_CCW_IO_IRQ_INDEX,
+       VFIO_CCW_CRW_IRQ_INDEX,
        VFIO_CCW_NUM_IRQS
 };
 

diff --git a/include/uapi/linux/vfio_ccw.h b/include/uapi/linux/vfio_ccw.h
index 758bf214898d3812ce463bcc3e0a4395daeec24c..aa04f3aa6db02f06192cdf287d9fc029e624f9bd 100644 (file)
--- a/include/uapi/linux/vfio_ccw.h
+++ b/include/uapi/linux/vfio_ccw.h
@@ -44,4 +44,13 @@ struct ccw_schib_region {
        __u8 schib_area[SCHIB_AREA_SIZE];
 } __packed;
 
+/*
+ * Used for returning a Channel Report Word to userspace.
+ * Note: this is controlled by a capability
+ */
+struct ccw_crw_region {
+       __u32 crw;
+       __u32 pad;
+} __packed;
+
 #endif