diff --git a/arch/powerpc/include/asm/vas.h b/arch/powerpc/include/asm/vas.h
index 163460cff59b..c1daab4cc205 100644
--- a/arch/powerpc/include/asm/vas.h
+++ b/arch/powerpc/include/asm/vas.h
@@ -230,4 +230,7 @@ int vas_register_coproc_api(struct module *mod, enum vas_cop_type cop_type,
 void vas_unregister_coproc_api(void);
 
 int get_vas_user_win_ref(struct vas_user_win_ref *task_ref);
+void vas_update_csb(struct coprocessor_request_block *crb,
+		    struct vas_user_win_ref *task_ref);
+void vas_dump_crb(struct coprocessor_request_block *crb);
 #endif /* __ASM_POWERPC_VAS_H */
diff --git a/arch/powerpc/platforms/book3s/vas-api.c b/arch/powerpc/platforms/book3s/vas-api.c
index 1d7d3273d34b..11c76c7141d2 100644
--- a/arch/powerpc/platforms/book3s/vas-api.c
+++ b/arch/powerpc/platforms/book3s/vas-api.c
@@ -10,6 +10,9 @@
 #include <linux/fs.h>
 #include <linux/slab.h>
 #include <linux/uaccess.h>
+#include <linux/kthread.h>
+#include <linux/sched/signal.h>
+#include <linux/mmu_context.h>
 #include <linux/io.h>
 #include <asm/vas.h>
 #include <uapi/asm/vas-api.h>
@@ -94,6 +97,150 @@ int get_vas_user_win_ref(struct vas_user_win_ref *task_ref)
 	return 0;
 }
 
+/*
+ * Update the CSB to indicate a translation error.
+ *
+ * User space will be polling on CSB after the request is issued.
+ * If NX can handle the request without any issues, it updates CSB.
+ * Whereas if NX encounters page fault, the kernel will handle the
+ * fault and update CSB with translation error.
+ *
+ * If we are unable to update the CSB means copy_to_user failed due to
+ * invalid csb_addr, send a signal to the process.
+ */
+void vas_update_csb(struct coprocessor_request_block *crb,
+		    struct vas_user_win_ref *task_ref)
+{
+	struct coprocessor_status_block csb;
+	struct kernel_siginfo info;
+	struct task_struct *tsk;
+	void __user *csb_addr;
+	struct pid *pid;
+	int rc;
+
+	/*
+	 * NX user space windows can not be opened for task->mm=NULL
+	 * and faults will not be generated for kernel requests.
+	 */
+	if (WARN_ON_ONCE(!task_ref->mm))
+		return;
+
+	csb_addr = (void __user *)be64_to_cpu(crb->csb_addr);
+
+	memset(&csb, 0, sizeof(csb));
+	csb.cc = CSB_CC_FAULT_ADDRESS;
+	csb.ce = CSB_CE_TERMINATION;
+	csb.cs = 0;
+	csb.count = 0;
+
+	/*
+	 * NX operates and returns in BE format as defined CRB struct.
+	 * So saves fault_storage_addr in BE as NX pastes in FIFO and
+	 * expects user space to convert to CPU format.
+	 */
+	csb.address = crb->stamp.nx.fault_storage_addr;
+	csb.flags = 0;
+
+	pid = task_ref->pid;
+	tsk = get_pid_task(pid, PIDTYPE_PID);
+	/*
+	 * Process closes send window after all pending NX requests are
+	 * completed. In multi-thread applications, a child thread can
+	 * open a window and can exit without closing it. May be some
+	 * requests are pending or this window can be used by other
+	 * threads later. We should handle faults if NX encounters
+	 * pages faults on these requests. Update CSB with translation
+	 * error and fault address. If csb_addr passed by user space is
+	 * invalid, send SEGV signal to pid saved in window. If the
+	 * child thread is not running, send the signal to tgid.
+	 * Parent thread (tgid) will close this window upon its exit.
+	 *
+	 * pid and mm references are taken when window is opened by
+	 * process (pid). So tgid is used only when child thread opens
+	 * a window and exits without closing it.
+	 */
+	if (!tsk) {
+		pid = task_ref->tgid;
+		tsk = get_pid_task(pid, PIDTYPE_PID);
+		/*
+		 * Parent thread (tgid) will be closing window when it
+		 * exits. So should not get here.
+		 */
+		if (WARN_ON_ONCE(!tsk))
+			return;
+	}
+
+	/* Return if the task is exiting. */
+	if (tsk->flags & PF_EXITING) {
+		put_task_struct(tsk);
+		return;
+	}
+
+	kthread_use_mm(task_ref->mm);
+	rc = copy_to_user(csb_addr, &csb, sizeof(csb));
+	/*
+	 * User space polls on csb.flags (first byte). So add barrier
+	 * then copy first byte with csb flags update.
+	 */
+	if (!rc) {
+		csb.flags = CSB_V;
+		/* Make sure update to csb.flags is visible now */
+		smp_mb();
+		rc = copy_to_user(csb_addr, &csb, sizeof(u8));
+	}
+	kthread_unuse_mm(task_ref->mm);
+	put_task_struct(tsk);
+
+	/* Success */
+	if (!rc)
+		return;
+
+
+	pr_debug("Invalid CSB address 0x%p signalling pid(%d)\n",
+			csb_addr, pid_vnr(pid));
+
+	clear_siginfo(&info);
+	info.si_signo = SIGSEGV;
+	info.si_errno = EFAULT;
+	info.si_code = SEGV_MAPERR;
+	info.si_addr = csb_addr;
+	/*
+	 * process will be polling on csb.flags after request is sent to
+	 * NX. So generally CSB update should not fail except when an
+	 * application passes invalid csb_addr. So an error message will
+	 * be displayed and leave it to user space whether to ignore or
+	 * handle this signal.
+	 */
+	rcu_read_lock();
+	rc = kill_pid_info(SIGSEGV, &info, pid);
+	rcu_read_unlock();
+
+	pr_devel("%s(): pid %d kill_proc_info() rc %d\n", __func__,
+			pid_vnr(pid), rc);
+}
+
+void vas_dump_crb(struct coprocessor_request_block *crb)
+{
+	struct data_descriptor_entry *dde;
+	struct nx_fault_stamp *nx;
+
+	dde = &crb->source;
+	pr_devel("SrcDDE: addr 0x%llx, len %d, count %d, idx %d, flags %d\n",
+		be64_to_cpu(dde->address), be32_to_cpu(dde->length),
+		dde->count, dde->index, dde->flags);
+
+	dde = &crb->target;
+	pr_devel("TgtDDE: addr 0x%llx, len %d, count %d, idx %d, flags %d\n",
+		be64_to_cpu(dde->address), be32_to_cpu(dde->length),
+		dde->count, dde->index, dde->flags);
+
+	nx = &crb->stamp.nx;
+	pr_devel("NX Stamp: PSWID 0x%x, FSA 0x%llx, flags 0x%x, FS 0x%x\n",
+		be32_to_cpu(nx->pswid),
+		be64_to_cpu(crb->stamp.nx.fault_storage_addr),
+		nx->flags, nx->fault_status);
+}
+
 static int coproc_open(struct inode *inode, struct file *fp)
 {
 	struct coproc_instance *cp_inst;
diff --git a/arch/powerpc/platforms/powernv/vas-fault.c b/arch/powerpc/platforms/powernv/vas-fault.c
index ac3a71ec3bd5..2729ac541fb3 100644
--- a/arch/powerpc/platforms/powernv/vas-fault.c
+++ b/arch/powerpc/platforms/powernv/vas-fault.c
@@ -26,150 +26,6 @@
  */
 #define VAS_FAULT_WIN_FIFO_SIZE	(4 << 20)
 
-static void dump_crb(struct coprocessor_request_block *crb)
-{
-	struct data_descriptor_entry *dde;
-	struct nx_fault_stamp *nx;
-
-	dde = &crb->source;
-	pr_devel("SrcDDE: addr 0x%llx, len %d, count %d, idx %d, flags %d\n",
-		be64_to_cpu(dde->address), be32_to_cpu(dde->length),
-		dde->count, dde->index, dde->flags);
-
-	dde = &crb->target;
-	pr_devel("TgtDDE: addr 0x%llx, len %d, count %d, idx %d, flags %d\n",
-		be64_to_cpu(dde->address), be32_to_cpu(dde->length),
-		dde->count, dde->index, dde->flags);
-
-	nx = &crb->stamp.nx;
-	pr_devel("NX Stamp: PSWID 0x%x, FSA 0x%llx, flags 0x%x, FS 0x%x\n",
-		be32_to_cpu(nx->pswid),
-		be64_to_cpu(crb->stamp.nx.fault_storage_addr),
-		nx->flags, nx->fault_status);
-}
-
-/*
- * Update the CSB to indicate a translation error.
- *
- * User space will be polling on CSB after the request is issued.
- * If NX can handle the request without any issues, it updates CSB.
- * Whereas if NX encounters page fault, the kernel will handle the
- * fault and update CSB with translation error.
- *
- * If we are unable to update the CSB means copy_to_user failed due to
- * invalid csb_addr, send a signal to the process.
- */
-static void update_csb(struct vas_window *window,
-			struct coprocessor_request_block *crb)
-{
-	struct coprocessor_status_block csb;
-	struct kernel_siginfo info;
-	struct task_struct *tsk;
-	void __user *csb_addr;
-	struct pid *pid;
-	int rc;
-
-	/*
-	 * NX user space windows can not be opened for task->mm=NULL
-	 * and faults will not be generated for kernel requests.
-	 */
-	if (WARN_ON_ONCE(!window->task_ref.mm || !window->user_win))
-		return;
-
-	csb_addr = (void __user *)be64_to_cpu(crb->csb_addr);
-
-	memset(&csb, 0, sizeof(csb));
-	csb.cc = CSB_CC_FAULT_ADDRESS;
-	csb.ce = CSB_CE_TERMINATION;
-	csb.cs = 0;
-	csb.count = 0;
-
-	/*
-	 * NX operates and returns in BE format as defined CRB struct.
-	 * So saves fault_storage_addr in BE as NX pastes in FIFO and
-	 * expects user space to convert to CPU format.
-	 */
-	csb.address = crb->stamp.nx.fault_storage_addr;
-	csb.flags = 0;
-
-	pid = window->task_ref.pid;
-	tsk = get_pid_task(pid, PIDTYPE_PID);
-	/*
-	 * Process closes send window after all pending NX requests are
-	 * completed. In multi-thread applications, a child thread can
-	 * open a window and can exit without closing it. May be some
-	 * requests are pending or this window can be used by other
-	 * threads later. We should handle faults if NX encounters
-	 * pages faults on these requests. Update CSB with translation
-	 * error and fault address. If csb_addr passed by user space is
-	 * invalid, send SEGV signal to pid saved in window. If the
-	 * child thread is not running, send the signal to tgid.
-	 * Parent thread (tgid) will close this window upon its exit.
-	 *
-	 * pid and mm references are taken when window is opened by
-	 * process (pid). So tgid is used only when child thread opens
-	 * a window and exits without closing it.
-	 */
-	if (!tsk) {
-		pid = window->task_ref.tgid;
-		tsk = get_pid_task(pid, PIDTYPE_PID);
-		/*
-		 * Parent thread (tgid) will be closing window when it
-		 * exits. So should not get here.
-		 */
-		if (WARN_ON_ONCE(!tsk))
-			return;
-	}
-
-	/* Return if the task is exiting. */
-	if (tsk->flags & PF_EXITING) {
-		put_task_struct(tsk);
-		return;
-	}
-
-	kthread_use_mm(window->task_ref.mm);
-	rc = copy_to_user(csb_addr, &csb, sizeof(csb));
-	/*
-	 * User space polls on csb.flags (first byte). So add barrier
-	 * then copy first byte with csb flags update.
-	 */
-	if (!rc) {
-		csb.flags = CSB_V;
-		/* Make sure update to csb.flags is visible now */
-		smp_mb();
-		rc = copy_to_user(csb_addr, &csb, sizeof(u8));
-	}
-	kthread_unuse_mm(window->task_ref.mm);
-	put_task_struct(tsk);
-
-	/* Success */
-	if (!rc)
-		return;
-
-	pr_debug("Invalid CSB address 0x%p signalling pid(%d)\n",
-			csb_addr, pid_vnr(pid));
-
-	clear_siginfo(&info);
-	info.si_signo = SIGSEGV;
-	info.si_errno = EFAULT;
-	info.si_code = SEGV_MAPERR;
-	info.si_addr = csb_addr;
-
-	/*
-	 * process will be polling on csb.flags after request is sent to
-	 * NX. So generally CSB update should not fail except when an
-	 * application passes invalid csb_addr. So an error message will
-	 * be displayed and leave it to user space whether to ignore or
-	 * handle this signal.
-	 */
-	rcu_read_lock();
-	rc = kill_pid_info(SIGSEGV, &info, pid);
-	rcu_read_unlock();
-
-	pr_devel("%s(): pid %d kill_proc_info() rc %d\n", __func__,
-			pid_vnr(pid), rc);
-}
-
 static void dump_fifo(struct vas_instance *vinst, void *entry)
 {
 	unsigned long *end = vinst->fault_fifo + vinst->fault_fifo_size;
@@ -272,7 +128,7 @@ irqreturn_t vas_fault_thread_fn(int irq, void *data)
 				vinst->vas_id, vinst->fault_fifo, fifo,
 				vinst->fault_crbs);
 
-		dump_crb(crb);
+		vas_dump_crb(crb);
 		window = vas_pswid_to_window(vinst,
 				be32_to_cpu(crb->stamp.nx.pswid));
 
@@ -293,7 +149,14 @@ irqreturn_t vas_fault_thread_fn(int irq, void *data)
 
 			WARN_ON_ONCE(1);
 		} else {
-			update_csb(window, crb);
+			/*
+			 * NX sees faults only with user space windows.
+			 */
+			if (window->user_win)
+				vas_update_csb(crb, &window->task_ref);
+			else
+				WARN_ON_ONCE(!window->user_win);
+
 			/*
 			 * Return credit for send window after processing
 			 * fault CRB.
