Merge tag 'vfio-ccw-20190717-2' of...

Merge tag 'vfio-ccw-20190717-2' of https://git.kernel.org/pub/scm/linux/kernel/git/kvms390/vfio-ccw into fixes

Fixes in vfio-ccw for older and newer issues.

Documentation/s390/vfio-ccw.rst

@@ -180,6 +180,13 @@ The process of how these work together.
    add it to an iommu_group and a vfio_group. Then we could pass through
    the mdev to a guest.
 
+
+VFIO-CCW Regions
+----------------
+
+The vfio-ccw driver exposes MMIO regions to accept requests from and return
+results to userspace.
+
 vfio-ccw I/O region
 -------------------
 
@@ -205,6 +212,25 @@ irb_area stores the I/O result.
 
 ret_code stores a return code for each access of the region.
 
+This region is always available.
+
+vfio-ccw cmd region
+-------------------
+
+The vfio-ccw cmd region is used to accept asynchronous instructions
+from userspace::
+
+  #define VFIO_CCW_ASYNC_CMD_HSCH (1 << 0)
+  #define VFIO_CCW_ASYNC_CMD_CSCH (1 << 1)
+  struct ccw_cmd_region {
+         __u32 command;
+         __u32 ret_code;
+  } __packed;
+
+This region is exposed via region type VFIO_REGION_SUBTYPE_CCW_ASYNC_CMD.
+
+Currently, CLEAR SUBCHANNEL and HALT SUBCHANNEL use this region.
+
 vfio-ccw operation details
 --------------------------
 
@@ -306,9 +332,8 @@ Together with the corresponding work in QEMU, we can bring the passed
 through DASD/ECKD device online in a guest now and use it as a block
 device.
 
-While the current code allows the guest to start channel programs via
-START SUBCHANNEL, support for HALT SUBCHANNEL or CLEAR SUBCHANNEL is
-not yet implemented.
+The current code allows the guest to start channel programs via
+START SUBCHANNEL, and to issue HALT SUBCHANNEL and CLEAR SUBCHANNEL.
 
 vfio-ccw supports classic (command mode) channel I/O only. Transport
 mode (HPF) is not supported.

drivers/s390/cio/vfio_ccw_cp.c

@@ -72,8 +72,10 @@ static int pfn_array_alloc(struct pfn_array *pa, u64 iova, unsigned int len)
 				  sizeof(*pa->pa_iova_pfn) +
 				  sizeof(*pa->pa_pfn),
 				  GFP_KERNEL);
-	if (unlikely(!pa->pa_iova_pfn))
+	if (unlikely(!pa->pa_iova_pfn)) {
+		pa->pa_nr = 0;
 		return -ENOMEM;
+	}
 	pa->pa_pfn = pa->pa_iova_pfn + pa->pa_nr;
 
 	pa->pa_iova_pfn[0] = pa->pa_iova >> PAGE_SHIFT;
@@ -421,7 +423,7 @@ static int ccwchain_loop_tic(struct ccwchain *chain,
 static int ccwchain_handle_ccw(u32 cda, struct channel_program *cp)
 {
 	struct ccwchain *chain;
-	int len;
+	int len, ret;
 
 	/* Copy 2K (the most we support today) of possible CCWs */
 	len = copy_from_iova(cp->mdev, cp->guest_cp, cda,
@@ -448,7 +450,12 @@ static int ccwchain_handle_ccw(u32 cda, struct channel_program *cp)
 	memcpy(chain->ch_ccw, cp->guest_cp, len * sizeof(struct ccw1));
 
 	/* Loop for tics on this new chain. */
-	return ccwchain_loop_tic(chain, cp);
+	ret = ccwchain_loop_tic(chain, cp);
+
+	if (ret)
+		ccwchain_free(chain);
+
+	return ret;
 }
 
 /* Loop for TICs. */
@@ -642,16 +649,15 @@ int cp_init(struct channel_program *cp, struct device *mdev, union orb *orb)
 
 	/* Build a ccwchain for the first CCW segment */
 	ret = ccwchain_handle_ccw(orb->cmd.cpa, cp);
-	if (ret)
-		cp_free(cp);
 
-	/* It is safe to force: if not set but idals used
-	 * ccwchain_calc_length returns an error.
+	if (!ret) {
+		cp->initialized = true;
+
+		/* It is safe to force: if it was not set but idals used
+		 * ccwchain_calc_length would have returned an error.
 		 */
 		cp->orb.cmd.c64 = 1;
-
-	if (!ret)
-		cp->initialized = true;
+	}
 
 	return ret;
 }

drivers/s390/cio/vfio_ccw_drv.c

@@ -88,7 +88,7 @@ static void vfio_ccw_sch_io_todo(struct work_struct *work)
 		     (SCSW_ACTL_DEVACT | SCSW_ACTL_SCHACT));
 	if (scsw_is_solicited(&irb->scsw)) {
 		cp_update_scsw(&private->cp, &irb->scsw);
-		if (is_final)
+		if (is_final && private->state == VFIO_CCW_STATE_CP_PENDING)
 			cp_free(&private->cp);
 	}
 	mutex_lock(&private->io_mutex);