10 files changed, 166 insertions, 13 deletions

diff --git a/drivers/misc/cxl/api.c b/drivers/misc/cxl/api.c
index f3d34b941f85..2e5233b60971 100644
--- a/drivers/misc/cxl/api.c
+++ b/drivers/misc/cxl/api.c
@@ -229,6 +229,14 @@ int cxl_start_context(struct cxl_context *ctx, u64 wed,
 	if (ctx->status == STARTED)
 		goto out; /* already started */
 
+	/*
+	 * Increment the mapped context count for adapter. This also checks
+	 * if adapter_context_lock is taken.
+	 */
+	rc = cxl_adapter_context_get(ctx->afu->adapter);
+	if (rc)
+		goto out;
+
 	if (task) {
 		ctx->pid = get_task_pid(task, PIDTYPE_PID);
 		ctx->glpid = get_task_pid(task->group_leader, PIDTYPE_PID);
@@ -239,7 +247,10 @@ int cxl_start_context(struct cxl_context *ctx, u64 wed,
 	cxl_ctx_get();
 
 	if ((rc = cxl_ops->attach_process(ctx, kernel, wed, 0))) {
+		put_pid(ctx->glpid);
 		put_pid(ctx->pid);
+		ctx->glpid = ctx->pid = NULL;
+		cxl_adapter_context_put(ctx->afu->adapter);
 		cxl_ctx_put();
 		goto out;
 	}
diff --git a/drivers/misc/cxl/context.c b/drivers/misc/cxl/context.c
index c466ee2b0c97..5e506c19108a 100644
--- a/drivers/misc/cxl/context.c
+++ b/drivers/misc/cxl/context.c
@@ -238,6 +238,9 @@ int __detach_context(struct cxl_context *ctx)
 	put_pid(ctx->glpid);
 
 	cxl_ctx_put();
+
+	/* Decrease the attached context count on the adapter */
+	cxl_adapter_context_put(ctx->afu->adapter);
 	return 0;
 }
 
diff --git a/drivers/misc/cxl/cxl.h b/drivers/misc/cxl/cxl.h
index 344a0ff8f8c7..a144073593fa 100644
--- a/drivers/misc/cxl/cxl.h
+++ b/drivers/misc/cxl/cxl.h
@@ -162,7 +162,10 @@ static const cxl_p2n_reg_t CXL_PSL_WED_An     = {0x0A0};
 #define CXL_PSL_SPAP_V    0x0000000000000001ULL
 
 /****** CXL_PSL_Control ****************************************************/
-#define CXL_PSL_Control_tb 0x0000000000000001ULL
+#define CXL_PSL_Control_tb              (0x1ull << (63-63))
+#define CXL_PSL_Control_Fr              (0x1ull << (63-31))
+#define CXL_PSL_Control_Fs_MASK         (0x3ull << (63-29))
+#define CXL_PSL_Control_Fs_Complete     (0x3ull << (63-29))
 
 /****** CXL_PSL_DLCNTL *****************************************************/
 #define CXL_PSL_DLCNTL_D (0x1ull << (63-28))
@@ -615,6 +618,14 @@ struct cxl {
 	bool perst_select_user;
 	bool perst_same_image;
 	bool psl_timebase_synced;
+
+	/*
+	 * number of contexts mapped on to this card. Possible values are:
+	 * >0: Number of contexts mapped and new one can be mapped.
+	 *  0: No active contexts and new ones can be mapped.
+	 * -1: No contexts mapped and new ones cannot be mapped.
+	 */
+	atomic_t contexts_num;
 };
 
 int cxl_pci_alloc_one_irq(struct cxl *adapter);
@@ -854,6 +865,7 @@ int cxl_register_one_irq(struct cxl *adapter, irq_handler_t handler,
 int cxl_check_error(struct cxl_afu *afu);
 int cxl_afu_slbia(struct cxl_afu *afu);
 int cxl_tlb_slb_invalidate(struct cxl *adapter);
+int cxl_data_cache_flush(struct cxl *adapter);
 int cxl_afu_disable(struct cxl_afu *afu);
 int cxl_psl_purge(struct cxl_afu *afu);
 
@@ -940,4 +952,20 @@ bool cxl_pci_is_vphb_device(struct pci_dev *dev);
 
 /* decode AFU error bits in the PSL register PSL_SERR_An */
 void cxl_afu_decode_psl_serr(struct cxl_afu *afu, u64 serr);
+
+/*
+ * Increments the number of attached contexts on an adapter.
+ * In case an adapter_context_lock is taken the return -EBUSY.
+ */
+int cxl_adapter_context_get(struct cxl *adapter);
+
+/* Decrements the number of attached contexts on an adapter */
+void cxl_adapter_context_put(struct cxl *adapter);
+
+/* If no active contexts then prevents contexts from being attached */
+int cxl_adapter_context_lock(struct cxl *adapter);
+
+/* Unlock the contexts-lock if taken. Warn and force unlock otherwise */
+void cxl_adapter_context_unlock(struct cxl *adapter);
+
 #endif
diff --git a/drivers/misc/cxl/file.c b/drivers/misc/cxl/file.c
index 5fb9894b157f..77080cc5fa0a 100644
--- a/drivers/misc/cxl/file.c
+++ b/drivers/misc/cxl/file.c
@@ -194,6 +194,16 @@ static long afu_ioctl_start_work(struct cxl_context *ctx,
 	ctx->mmio_err_ff = !!(work.flags & CXL_START_WORK_ERR_FF);
 
 	/*
+	 * Increment the mapped context count for adapter. This also checks
+	 * if adapter_context_lock is taken.
+	 */
+	rc = cxl_adapter_context_get(ctx->afu->adapter);
+	if (rc) {
+		afu_release_irqs(ctx, ctx);
+		goto out;
+	}
+
+	/*
 	 * We grab the PID here and not in the file open to allow for the case
 	 * where a process (master, some daemon, etc) has opened the chardev on
 	 * behalf of another process, so the AFU's mm gets bound to the process
@@ -205,11 +215,16 @@ static long afu_ioctl_start_work(struct cxl_context *ctx,
 	ctx->pid = get_task_pid(current, PIDTYPE_PID);
 	ctx->glpid = get_task_pid(current->group_leader, PIDTYPE_PID);
 
+
 	trace_cxl_attach(ctx, work.work_element_descriptor, work.num_interrupts, amr);
 
 	if ((rc = cxl_ops->attach_process(ctx, false, work.work_element_descriptor,
 							amr))) {
 		afu_release_irqs(ctx, ctx);
+		cxl_adapter_context_put(ctx->afu->adapter);
+		put_pid(ctx->glpid);
+		put_pid(ctx->pid);
+		ctx->glpid = ctx->pid = NULL;
 		goto out;
 	}
 
diff --git a/drivers/misc/cxl/guest.c b/drivers/misc/cxl/guest.c
index 9aa58a77a24d..3e102cd6ed91 100644
--- a/drivers/misc/cxl/guest.c
+++ b/drivers/misc/cxl/guest.c
@@ -1152,6 +1152,9 @@ struct cxl *cxl_guest_init_adapter(struct device_node *np, struct platform_devic
 	if ((rc = cxl_sysfs_adapter_add(adapter)))
 		goto err_put1;
 
+	/* release the context lock as the adapter is configured */
+	cxl_adapter_context_unlock(adapter);
+
 	return adapter;
 
 err_put1:
diff --git a/drivers/misc/cxl/main.c b/drivers/misc/cxl/main.c
index d9be23b24aa3..62e0dfb5f15b 100644
--- a/drivers/misc/cxl/main.c
+++ b/drivers/misc/cxl/main.c
@@ -243,8 +243,10 @@ struct cxl *cxl_alloc_adapter(void)
 	if (dev_set_name(&adapter->dev, "card%i", adapter->adapter_num))
 		goto err2;
 
-	return adapter;
+	/* start with context lock taken */
+	atomic_set(&adapter->contexts_num, -1);
 
+	return adapter;
 err2:
 	cxl_remove_adapter_nr(adapter);
 err1:
@@ -286,6 +288,44 @@ int cxl_afu_select_best_mode(struct cxl_afu *afu)
 	return 0;
 }
 
+int cxl_adapter_context_get(struct cxl *adapter)
+{
+	int rc;
+
+	rc = atomic_inc_unless_negative(&adapter->contexts_num);
+	return rc >= 0 ? 0 : -EBUSY;
+}
+
+void cxl_adapter_context_put(struct cxl *adapter)
+{
+	atomic_dec_if_positive(&adapter->contexts_num);
+}
+
+int cxl_adapter_context_lock(struct cxl *adapter)
+{
+	int rc;
+	/* no active contexts -> contexts_num == 0 */
+	rc = atomic_cmpxchg(&adapter->contexts_num, 0, -1);
+	return rc ? -EBUSY : 0;
+}
+
+void cxl_adapter_context_unlock(struct cxl *adapter)
+{
+	int val = atomic_cmpxchg(&adapter->contexts_num, -1, 0);
+
+	/*
+	 * contexts lock taken -> contexts_num == -1
+	 * If not true then show a warning and force reset the lock.
+	 * This will happen when context_unlock was requested without
+	 * doing a context_lock.
+	 */
+	if (val != -1) {
+		atomic_set(&adapter->contexts_num, 0);
+		WARN(1, "Adapter context unlocked with %d active contexts",
+		     val);
+	}
+}
+
 static int __init init_cxl(void)
 {
 	int rc = 0;
diff --git a/drivers/misc/cxl/native.c b/drivers/misc/cxl/native.c
index e606fdc4bc9c..a217a74ccc98 100644
--- a/drivers/misc/cxl/native.c
+++ b/drivers/misc/cxl/native.c
@@ -290,6 +290,37 @@ int cxl_tlb_slb_invalidate(struct cxl *adapter)
 	return 0;
 }
 
+int cxl_data_cache_flush(struct cxl *adapter)
+{
+	u64 reg;
+	unsigned long timeout = jiffies + (HZ * CXL_TIMEOUT);
+
+	pr_devel("Flushing data cache\n");
+
+	reg = cxl_p1_read(adapter, CXL_PSL_Control);
+	reg |= CXL_PSL_Control_Fr;
+	cxl_p1_write(adapter, CXL_PSL_Control, reg);
+
+	reg = cxl_p1_read(adapter, CXL_PSL_Control);
+	while ((reg & CXL_PSL_Control_Fs_MASK) != CXL_PSL_Control_Fs_Complete) {
+		if (time_after_eq(jiffies, timeout)) {
+			dev_warn(&adapter->dev, "WARNING: cache flush timed out!\n");
+			return -EBUSY;
+		}
+
+		if (!cxl_ops->link_ok(adapter, NULL)) {
+			dev_warn(&adapter->dev, "WARNING: link down when flushing cache\n");
+			return -EIO;
+		}
+		cpu_relax();
+		reg = cxl_p1_read(adapter, CXL_PSL_Control);
+	}
+
+	reg &= ~CXL_PSL_Control_Fr;
+	cxl_p1_write(adapter, CXL_PSL_Control, reg);
+	return 0;
+}
+
 static int cxl_write_sstp(struct cxl_afu *afu, u64 sstp0, u64 sstp1)
 {
 	int rc;
diff --git a/drivers/misc/cxl/of.c b/drivers/misc/cxl/of.c
index edc458395f68..ec175ea5dfba 100644
--- a/drivers/misc/cxl/of.c
+++ b/drivers/misc/cxl/of.c
@@ -460,7 +460,7 @@ int cxl_of_probe(struct platform_device *pdev)
 	struct device_node *afu_np = NULL;
 	struct cxl *adapter = NULL;
 	int ret;
-	int slice, slice_ok;
+	int slice = 0, slice_ok = 0;
 
 	pr_devel("in %s\n", __func__);
 
@@ -476,13 +476,13 @@ int cxl_of_probe(struct platform_device *pdev)
 	}
 
 	/* init afu */
-	slice_ok = 0;
-	for (afu_np = NULL, slice = 0; (afu_np = of_get_next_child(np, afu_np)); slice++) {
+	for_each_child_of_node(np, afu_np) {
 		if ((ret = cxl_guest_init_afu(adapter, slice, afu_np)))
 			dev_err(&pdev->dev, "AFU %i failed to initialise: %i\n",
 				slice, ret);
 		else
 			slice_ok++;
+		slice++;
 	}
 
 	if (slice_ok == 0) {
@@ -490,8 +490,6 @@ int cxl_of_probe(struct platform_device *pdev)
 		adapter->slices = 0;
 	}
 
-	if (afu_np)
-		of_node_put(afu_np);
 	return 0;
 }
 
diff --git a/drivers/misc/cxl/pci.c b/drivers/misc/cxl/pci.c
index 6f0c4ac4b649..e96be9ca4e60 100644
--- a/drivers/misc/cxl/pci.c
+++ b/drivers/misc/cxl/pci.c
@@ -1239,6 +1239,9 @@ int cxl_pci_reset(struct cxl *adapter)
 
 	dev_info(&dev->dev, "CXL reset\n");
 
+	/* the adapter is about to be reset, so ignore errors */
+	cxl_data_cache_flush(adapter);
+
 	/* pcie_warm_reset requests a fundamental pci reset which includes a
 	 * PERST assert/deassert.  PERST triggers a loading of the image
 	 * if "user" or "factory" is selected in sysfs */
@@ -1484,6 +1487,8 @@ static int cxl_configure_adapter(struct cxl *adapter, struct pci_dev *dev)
 	if ((rc = cxl_native_register_psl_err_irq(adapter)))
 		goto err;
 
+	/* Release the context lock as adapter is configured */
+	cxl_adapter_context_unlock(adapter);
 	return 0;
 
 err:
@@ -1530,11 +1535,11 @@ static void set_sl_ops(struct cxl *adapter, struct pci_dev *dev)
 {
 	if (dev->vendor == PCI_VENDOR_ID_MELLANOX && dev->device == 0x1013) {
 		/* Mellanox CX-4 */
-		dev_info(&adapter->dev, "Device uses an XSL\n");
+		dev_info(&dev->dev, "Device uses an XSL\n");
 		adapter->native->sl_ops = &xsl_ops;
 		adapter->min_pe = 1; /* Workaround for CX-4 hardware bug */
 	} else {
-		dev_info(&adapter->dev, "Device uses a PSL\n");
+		dev_info(&dev->dev, "Device uses a PSL\n");
 		adapter->native->sl_ops = &psl_ops;
 	}
 }
diff --git a/drivers/misc/cxl/sysfs.c b/drivers/misc/cxl/sysfs.c
index b043c20f158f..a8b6d6a635e9 100644
--- a/drivers/misc/cxl/sysfs.c
+++ b/drivers/misc/cxl/sysfs.c
@@ -75,12 +75,31 @@ static ssize_t reset_adapter_store(struct device *device,
 	int val;
 
 	rc = sscanf(buf, "%i", &val);
-	if ((rc != 1) || (val != 1))
+	if ((rc != 1) || (val != 1 && val != -1))
 		return -EINVAL;
 
-	if ((rc = cxl_ops->adapter_reset(adapter)))
-		return rc;
-	return count;
+	/*
+	 * See if we can lock the context mapping that's only allowed
+	 * when there are no contexts attached to the adapter. Once
+	 * taken this will also prevent any context from getting activated.
+	 */
+	if (val == 1) {
+		rc =  cxl_adapter_context_lock(adapter);
+		if (rc)
+			goto out;
+
+		rc = cxl_ops->adapter_reset(adapter);
+		/* In case reset failed release context lock */
+		if (rc)
+			cxl_adapter_context_unlock(adapter);
+
+	} else if (val == -1) {
+		/* Perform a forced adapter reset */
+		rc = cxl_ops->adapter_reset(adapter);
+	}
+
+out:
+	return rc ? rc : count;
 }
 
 static ssize_t load_image_on_perst_show(struct device *device,