[RFC PATCH 11/13] powerpc/vas: Return credits after handling fault

[Haren Myneni]

NX expects OS to return credit for send window after processing each
fault. Also credit has to be returned even for fault window.

Signed-off-by: Sukadev Bhattiprolu <sukadev at linux.vnet.ibm.com>
Signed-off-by: Haren Myneni <haren at us.ibm.com>
---
 arch/powerpc/platforms/powernv/vas-fault.c  | 10 ++++++++++
 arch/powerpc/platforms/powernv/vas-window.c | 19 +++++++++++++++++++
 arch/powerpc/platforms/powernv/vas.h        |  1 +
 3 files changed, 30 insertions(+)

diff --git a/arch/powerpc/platforms/powernv/vas-fault.c b/arch/powerpc/platforms/powernv/vas-fault.c
index 98100c7..dff61ea 100644
--- a/arch/powerpc/platforms/powernv/vas-fault.c
+++ b/arch/powerpc/platforms/powernv/vas-fault.c
@@ -253,6 +253,11 @@ static void process_fault_crbs(struct vas_instance *vinst)
 		memset(fifo, 0, CRB_SIZE);
 		mutex_unlock(&vinst->mutex);
 
+		/*
+		 *
+		 * Return credit for the fault window.
+		 */
+		vas_return_credit(vinst->fault_win, 0);
 		pr_devel("VAS[%d] fault_fifo %p, fifo %p, fault_crbs %d "
 				"pending %d\n", vinst->vas_id,
 				vinst->fault_fifo, fifo, vinst->fault_crbs,
@@ -281,6 +286,11 @@ static void process_fault_crbs(struct vas_instance *vinst)
 		}
 
 		update_csb(window, crb);
+		/*
+		 * Return credit for send window after processing
+		 * fault CRB.
+		 */
+		vas_return_credit(window, 1);
 	} while (true);
 }
 
diff --git a/arch/powerpc/platforms/powernv/vas-window.c b/arch/powerpc/platforms/powernv/vas-window.c
index 9d32d97..85a60ac 100644
--- a/arch/powerpc/platforms/powernv/vas-window.c
+++ b/arch/powerpc/platforms/powernv/vas-window.c
@@ -1284,6 +1284,25 @@ int vas_win_close(struct vas_window *window)
 EXPORT_SYMBOL_GPL(vas_win_close);
 
 /*
+ * Return credit for the given window.
+ */
+void vas_return_credit(struct vas_window *window, bool tx)
+{
+	uint64_t val;
+
+	val = 0ULL;
+	if (tx) { /* send window */
+		val = SET_FIELD(VAS_TX_WCRED, val, 1);
+		write_hvwc_reg(window, VREG(TX_WCRED_ADDER), val);
+	} else {
+		val = SET_FIELD(VAS_LRX_WCRED, val, 1);
+		write_hvwc_reg(window, VREG(LRX_WCRED_ADDER), val);
+	}
+
+	return;
+}
+
+/*
  * Return a system-wide unique window id for the window @win.
  */
 u32 vas_win_id(struct vas_window *win)
diff --git a/arch/powerpc/platforms/powernv/vas.h b/arch/powerpc/platforms/powernv/vas.h
index d1e32a0..a8c9741 100644
--- a/arch/powerpc/platforms/powernv/vas.h
+++ b/arch/powerpc/platforms/powernv/vas.h
@@ -420,6 +420,7 @@ struct vas_winctx {
 extern void vas_wakeup_fault_handler(int virq, void *arg);
 extern int vas_setup_fault_handler(struct vas_instance *vinst);
 extern void vas_cleanup_fault_handler(struct vas_instance *vinst);
+extern void vas_return_credit(struct vas_window *window, bool tx);
 extern struct vas_window *vas_pswid_to_window(struct vas_instance *vinst,
 						uint32_t pswid);
 
-- 
1.8.3.1