vfio-ccw: Introduce a new schib region

The schib region can be used by userspace to get the subchannel-
information block (SCHIB) for the passthrough subchannel.
This can be useful to get information such as channel path
information via the SCHIB.PMCW fields.

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: <20200505122745.53208-5-farman@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>

diff --git a/Documentation/s390/vfio-ccw.rst b/Documentation/s390/vfio-ccw.rst
index 3a946fd455629d93b2d36f7cde861fa492491f96..32310df525bacf3350ee1e00f147d768293fc21c 100644 (file)
--- a/Documentation/s390/vfio-ccw.rst
+++ b/Documentation/s390/vfio-ccw.rst
@@ -282,6 +282,21 @@ for each access of the region. The following values may occur:
 ``-EBUSY``
   The subchannel was status pending or busy while processing a halt request.
 
+vfio-ccw schib region
+---------------------
+
+The vfio-ccw schib region is used to return Subchannel-Information
+Block (SCHIB) data to userspace::
+
+  struct ccw_schib_region {
+  #define SCHIB_AREA_SIZE 52
+         __u8 schib_area[SCHIB_AREA_SIZE];
+  } __packed;
+
+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 operation details
 --------------------------
@@ -385,7 +400,8 @@ through DASD/ECKD device online in a guest now and use it as a block
 device.
 
 The current code allows the guest to start channel programs via
-START SUBCHANNEL, and to issue HALT SUBCHANNEL and CLEAR SUBCHANNEL.
+START SUBCHANNEL, and to issue HALT SUBCHANNEL, CLEAR SUBCHANNEL,
+and STORE SUBCHANNEL.
 
 Currently all channel programs are prefetched, regardless of the
 p-bit setting in the ORB.  As a result, self modifying channel

diff --git a/drivers/s390/cio/Makefile b/drivers/s390/cio/Makefile
index 23eae41888760c517fe7dedf8cc45b9ee45b0c60..a9235f111e797adfe3f479bdf6b27b2f3edcc61a 100644 (file)
--- a/drivers/s390/cio/Makefile
+++ b/drivers/s390/cio/Makefile
@@ -21,5 +21,5 @@ qdio-objs := qdio_main.o qdio_thinint.o qdio_debug.o qdio_setup.o
 obj-$(CONFIG_QDIO) += qdio.o
 
 vfio_ccw-objs += vfio_ccw_drv.o vfio_ccw_cp.o vfio_ccw_ops.o vfio_ccw_fsm.o \
-       vfio_ccw_async.o vfio_ccw_trace.o
+       vfio_ccw_async.o vfio_ccw_trace.o vfio_ccw_chp.o
 obj-$(CONFIG_VFIO_CCW) += vfio_ccw.o

diff --git a/drivers/s390/cio/vfio_ccw_chp.c b/drivers/s390/cio/vfio_ccw_chp.c
new file mode 100644 (file)
index 0000000..18f3b3e
--- /dev/null
+++ b/drivers/s390/cio/vfio_ccw_chp.c
@@ -0,0 +1,76 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Channel path related status regions for vfio_ccw
+ *
+ * Copyright IBM Corp. 2020
+ *
+ * Author(s): Farhan Ali <alifm@linux.ibm.com>
+ *            Eric Farman <farman@linux.ibm.com>
+ */
+
+#include <linux/vfio.h>
+#include "vfio_ccw_private.h"
+
+static ssize_t vfio_ccw_schib_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_schib_region *region;
+       int ret;
+
+       if (pos + count > sizeof(*region))
+               return -EINVAL;
+
+       mutex_lock(&private->io_mutex);
+       region = private->region[i].data;
+
+       if (cio_update_schib(private->sch)) {
+               ret = -ENODEV;
+               goto out;
+       }
+
+       memcpy(region, &private->sch->schib, sizeof(*region));
+
+       if (copy_to_user(buf, (void *)region + pos, count)) {
+               ret = -EFAULT;
+               goto out;
+       }
+
+       ret = count;
+
+out:
+       mutex_unlock(&private->io_mutex);
+       return ret;
+}
+
+static ssize_t vfio_ccw_schib_region_write(struct vfio_ccw_private *private,
+                                          const char __user *buf, size_t count,
+                                          loff_t *ppos)
+{
+       return -EINVAL;
+}
+
+
+static void vfio_ccw_schib_region_release(struct vfio_ccw_private *private,
+                                         struct vfio_ccw_region *region)
+{
+
+}
+
+const struct vfio_ccw_regops vfio_ccw_schib_region_ops = {
+       .read = vfio_ccw_schib_region_read,
+       .write = vfio_ccw_schib_region_write,
+       .release = vfio_ccw_schib_region_release,
+};
+
+int vfio_ccw_register_schib_dev_regions(struct vfio_ccw_private *private)
+{
+       return vfio_ccw_register_dev_region(private,
+                                           VFIO_REGION_SUBTYPE_CCW_SCHIB,
+                                           &vfio_ccw_schib_region_ops,
+                                           sizeof(struct ccw_schib_region),
+                                           VFIO_REGION_INFO_FLAG_READ,
+                                           private->schib_region);
+}

diff --git a/drivers/s390/cio/vfio_ccw_drv.c b/drivers/s390/cio/vfio_ccw_drv.c
index fb1275a7d1f5c3b3f7250cf7f99d7470baa0e3cd..7aeff42f370d70a21363668c634d089ee9874f6e 100644 (file)
--- a/drivers/s390/cio/vfio_ccw_drv.c
+++ b/drivers/s390/cio/vfio_ccw_drv.c
@@ -27,6 +27,7 @@
 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;
 
 debug_info_t *vfio_ccw_debug_msg_id;
 debug_info_t *vfio_ccw_debug_trace_id;
@@ -119,6 +120,8 @@ static void vfio_ccw_sch_irq(struct subchannel *sch)
 
 static void vfio_ccw_free_regions(struct vfio_ccw_private *private)
 {
+       if (private->schib_region)
+               kmem_cache_free(vfio_ccw_schib_region, private->schib_region);
        if (private->cmd_region)
                kmem_cache_free(vfio_ccw_cmd_region, private->cmd_region);
        if (private->io_region)
@@ -156,6 +159,12 @@ static int vfio_ccw_sch_probe(struct subchannel *sch)
        if (!private->cmd_region)
                goto out_free;
 
+       private->schib_region = kmem_cache_zalloc(vfio_ccw_schib_region,
+                                                 GFP_KERNEL | GFP_DMA);
+
+       if (!private->schib_region)
+               goto out_free;
+
        private->sch = sch;
        dev_set_drvdata(&sch->dev, private);
        mutex_init(&private->io_mutex);
@@ -357,6 +366,7 @@ static void vfio_ccw_debug_exit(void)
 
 static void vfio_ccw_destroy_regions(void)
 {
+       kmem_cache_destroy(vfio_ccw_schib_region);
        kmem_cache_destroy(vfio_ccw_cmd_region);
        kmem_cache_destroy(vfio_ccw_io_region);
 }
@@ -393,6 +403,16 @@ static int __init vfio_ccw_sch_init(void)
                goto out_err;
        }
 
+       vfio_ccw_schib_region = kmem_cache_create_usercopy("vfio_ccw_schib_region",
+                                       sizeof(struct ccw_schib_region), 0,
+                                       SLAB_ACCOUNT, 0,
+                                       sizeof(struct ccw_schib_region), NULL);
+
+       if (!vfio_ccw_schib_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 d4fc84b8867f875d60609d4ded85dbd7d856ce4f..22988d67b6bb382bc0bd8a41fe3dffac375d11de 100644 (file)
--- a/drivers/s390/cio/vfio_ccw_ops.c
+++ b/drivers/s390/cio/vfio_ccw_ops.c
@@ -172,8 +172,18 @@ static int vfio_ccw_mdev_open(struct mdev_device *mdev)
 
        ret = vfio_ccw_register_async_dev_regions(private);
        if (ret)
-               vfio_unregister_notifier(mdev_dev(mdev), VFIO_IOMMU_NOTIFY,
-                                        &private->nb);
+               goto out_unregister;
+
+       ret = vfio_ccw_register_schib_dev_regions(private);
+       if (ret)
+               goto out_unregister;
+
+       return ret;
+
+out_unregister:
+       vfio_ccw_unregister_dev_regions(private);
+       vfio_unregister_notifier(mdev_dev(mdev), VFIO_IOMMU_NOTIFY,
+                                &private->nb);
        return ret;
 }
 

diff --git a/drivers/s390/cio/vfio_ccw_private.h b/drivers/s390/cio/vfio_ccw_private.h
index ce3834159d985ad965037dd5e86ec0f5cf4e647f..d6601a8adf137ff4a930b6fd50288837152aef1d 100644 (file)
--- a/drivers/s390/cio/vfio_ccw_private.h
+++ b/drivers/s390/cio/vfio_ccw_private.h
@@ -56,6 +56,7 @@ int vfio_ccw_register_dev_region(struct vfio_ccw_private *private,
 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);
 
 /**
  * struct vfio_ccw_private
@@ -69,6 +70,7 @@ int vfio_ccw_register_async_dev_regions(struct vfio_ccw_private *private);
  * @io_mutex: protect against concurrent update of I/O regions
  * @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
  * @num_regions: number of additional regions
  * @cp: channel program for the current I/O operation
  * @irb: irb info received from interrupt
@@ -87,6 +89,7 @@ struct vfio_ccw_private {
        struct mutex            io_mutex;
        struct vfio_ccw_region *region;
        struct ccw_cmd_region   *cmd_region;
+       struct ccw_schib_region *schib_region;
        int num_regions;
 
        struct channel_program  cp;

diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 015516bcfaa3caad0253f09e4dbc5dc5e6e94af3..7a1abbd889bd8d74c33ee48309e55f0dec759db5 100644 (file)
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -378,6 +378,7 @@ 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)
 
 /*
  * The MSIX mappable capability informs that MSIX data of a BAR can be mmapped

diff --git a/include/uapi/linux/vfio_ccw.h b/include/uapi/linux/vfio_ccw.h
index cbecbf0cd54f4a167147f3ed95da04b861e7c085..758bf214898d3812ce463bcc3e0a4395daeec24c 100644 (file)
--- a/include/uapi/linux/vfio_ccw.h
+++ b/include/uapi/linux/vfio_ccw.h
@@ -34,4 +34,14 @@ struct ccw_cmd_region {
        __u32 ret_code;
 } __packed;
 
+/*
+ * Used for processing commands that read the subchannel-information block
+ * Reading this region triggers a stsch() to hardware
+ * Note: this is controlled by a capability
+ */
+struct ccw_schib_region {
+#define SCHIB_AREA_SIZE 52
+       __u8 schib_area[SCHIB_AREA_SIZE];
+} __packed;
+
 #endif