RDMA/hfi1: Defer setting VL15 credits to link-up interrupt

Keep VL15 credits at 0 during LNI, before link-up. Store
VL15 credits value during verify cap interrupt and set
in after link-up. This addresses an issue where VL15 MAD
packets could be sent by one side of the link before
the other side is ready to receive them.

Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Reviewed-by: Dean Luick <dean.luick@intel.com>
Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Jakub Byczkowski <jakub.byczkowski@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

4 files changed, 64 insertions, 19 deletions

diff --git a/drivers/infiniband/hw/hfi1/chip.c b/drivers/infiniband/hw/hfi1/chip.c
index 5d6b1eeaa9a0..2ba00b89df6a 100644
--- a/drivers/infiniband/hw/hfi1/chip.c
+++ b/drivers/infiniband/hw/hfi1/chip.c
@@ -6312,25 +6312,38 @@ static void handle_8051_request(struct hfi1_pportdata *ppd)
         }
 }
 
-static void write_global_credit(struct hfi1_devdata *dd,
-                                u8 vau, u16 total, u16 shared)
+/*
+ * Set up allocation unit vaulue.
+ */
+void set_up_vau(struct hfi1_devdata *dd, u8 vau)
 {
-        write_csr(dd, SEND_CM_GLOBAL_CREDIT,
-                  ((u64)total <<
-                   SEND_CM_GLOBAL_CREDIT_TOTAL_CREDIT_LIMIT_SHIFT) |
-                  ((u64)shared <<
-                   SEND_CM_GLOBAL_CREDIT_SHARED_LIMIT_SHIFT) |
-                  ((u64)vau << SEND_CM_GLOBAL_CREDIT_AU_SHIFT));
+        u64 reg = read_csr(dd, SEND_CM_GLOBAL_CREDIT);
+
+        /* do not modify other values in the register */
+        reg &= ~SEND_CM_GLOBAL_CREDIT_AU_SMASK;
+        reg |= (u64)vau << SEND_CM_GLOBAL_CREDIT_AU_SHIFT;
+        write_csr(dd, SEND_CM_GLOBAL_CREDIT, reg);
 }
 
 /*
  * Set up initial VL15 credits of the remote.  Assumes the rest of
- * the CM credit registers are zero from a previous global or credit reset .
+ * the CM credit registers are zero from a previous global or credit reset.
+ * Shared limit for VL15 will always be 0.
  */
-void set_up_vl15(struct hfi1_devdata *dd, u8 vau, u16 vl15buf)
+void set_up_vl15(struct hfi1_devdata *dd, u16 vl15buf)
 {
-        /* leave shared count at zero for both global and VL15 */
-        write_global_credit(dd, vau, vl15buf, 0);
+        u64 reg = read_csr(dd, SEND_CM_GLOBAL_CREDIT);
+
+        /* set initial values for total and shared credit limit */
+        reg &= ~(SEND_CM_GLOBAL_CREDIT_TOTAL_CREDIT_LIMIT_SMASK |
+                 SEND_CM_GLOBAL_CREDIT_SHARED_LIMIT_SMASK);
+
+        /*
+         * Set total limit to be equal to VL15 credits.
+         * Leave shared limit at 0.
+         */
+        reg |= (u64)vl15buf << SEND_CM_GLOBAL_CREDIT_TOTAL_CREDIT_LIMIT_SHIFT;
+        write_csr(dd, SEND_CM_GLOBAL_CREDIT, reg);
 
         write_csr(dd, SEND_CM_CREDIT_VL15, (u64)vl15buf
                   << SEND_CM_CREDIT_VL15_DEDICATED_LIMIT_VL_SHIFT);
@@ -6348,9 +6361,11 @@ void reset_link_credits(struct hfi1_devdata *dd)
         for (i = 0; i < TXE_NUM_DATA_VL; i++)
                 write_csr(dd, SEND_CM_CREDIT_VL + (8 * i), 0);
         write_csr(dd, SEND_CM_CREDIT_VL15, 0);
-        write_global_credit(dd, 0, 0, 0);
+        write_csr(dd, SEND_CM_GLOBAL_CREDIT, 0);
         /* reset the CM block */
         pio_send_control(dd, PSC_CM_RESET);
+        /* reset cached value */
+        dd->vl15buf_cached = 0;
 }
 
 /* convert a vCU to a CU */
@@ -6839,24 +6854,35 @@ void handle_link_up(struct work_struct *work)
 {
         struct hfi1_pportdata *ppd = container_of(work, struct hfi1_pportdata,
                                                   link_up_work);
+        struct hfi1_devdata *dd = ppd->dd;
+
         set_link_state(ppd, HLS_UP_INIT);
 
         /* cache the read of DC_LCB_STS_ROUND_TRIP_LTP_CNT */
-        read_ltp_rtt(ppd->dd);
+        read_ltp_rtt(dd);
         /*
          * OPA specifies that certain counters are cleared on a transition
          * to link up, so do that.
          */
-        clear_linkup_counters(ppd->dd);
+        clear_linkup_counters(dd);
         /*
          * And (re)set link up default values.
          */
         set_linkup_defaults(ppd);
 
+        /*
+         * Set VL15 credits. Use cached value from verify cap interrupt.
+         * In case of quick linkup or simulator, vl15 value will be set by
+         * handle_linkup_change. VerifyCap interrupt handler will not be
+         * called in those scenarios.
+         */
+        if (!(quick_linkup || dd->icode == ICODE_FUNCTIONAL_SIMULATOR))
+                set_up_vl15(dd, dd->vl15buf_cached);
+
         /* enforce link speed enabled */
         if ((ppd->link_speed_active & ppd->link_speed_enabled) == 0) {
                 /* oops - current speed is not enabled, bounce */
-                dd_dev_err(ppd->dd,
+                dd_dev_err(dd,
                            "Link speed active 0x%x is outside enabled 0x%x, downing link\n",
                            ppd->link_speed_active, ppd->link_speed_enabled);
                 set_link_down_reason(ppd, OPA_LINKDOWN_REASON_SPEED_POLICY, 0,
@@ -7357,7 +7383,14 @@ void handle_verify_cap(struct work_struct *work)
          */
         if (vau == 0)
                 vau = 1;
-        set_up_vl15(dd, vau, vl15buf);
+        set_up_vau(dd, vau);
+
+        /*
+         * Set VL15 credits to 0 in global credit register. Cache remote VL15
+         * credits value and wait for link-up interrupt ot set it.
+         */
+        set_up_vl15(dd, 0);
+        dd->vl15buf_cached = vl15buf;
 
         /* set up the LCB CRC mode */
         crc_mask = ppd->port_crc_mode_enabled & partner_supported_crc;
diff --git a/drivers/infiniband/hw/hfi1/chip_registers.h b/drivers/infiniband/hw/hfi1/chip_registers.h
index 5bfa839d1c48..793514f1d15f 100644
--- a/drivers/infiniband/hw/hfi1/chip_registers.h
+++ b/drivers/infiniband/hw/hfi1/chip_registers.h
@@ -839,7 +839,9 @@
 #define SEND_CM_CTRL_FORCE_CREDIT_MODE_SMASK 0x8ull
 #define SEND_CM_CTRL_RESETCSR 0x0000000000000020ull
 #define SEND_CM_GLOBAL_CREDIT (TXE + 0x000000000508)
+#define SEND_CM_GLOBAL_CREDIT_AU_MASK 0x7ull
 #define SEND_CM_GLOBAL_CREDIT_AU_SHIFT 16
+#define SEND_CM_GLOBAL_CREDIT_AU_SMASK 0x70000ull
 #define SEND_CM_GLOBAL_CREDIT_RESETCSR 0x0000094000030000ull
 #define SEND_CM_GLOBAL_CREDIT_SHARED_LIMIT_MASK 0xFFFFull
 #define SEND_CM_GLOBAL_CREDIT_SHARED_LIMIT_SHIFT 0
diff --git a/drivers/infiniband/hw/hfi1/hfi.h b/drivers/infiniband/hw/hfi1/hfi.h
index da322e6668cc..414a04a481c2 100644
--- a/drivers/infiniband/hw/hfi1/hfi.h
+++ b/drivers/infiniband/hw/hfi1/hfi.h
@@ -1045,6 +1045,14 @@ struct hfi1_devdata {
         /* initial vl15 credits to use */
         u16 vl15_init;
 
+        /*
+         * Cached value for vl15buf, read during verify cap interrupt. VL15
+         * credits are to be kept at 0 and set when handling the link-up
+         * interrupt. This removes the possibility of receiving VL15 MAD
+         * packets before this HFI is ready.
+         */
+        u16 vl15buf_cached;
+
         /* Misc small ints */
         u8 n_krcv_queues;
         u8 qos_shift;
@@ -1598,7 +1606,8 @@ int hfi1_rcvbuf_validate(u32 size, u8 type, u16 *encode);
 int fm_get_table(struct hfi1_pportdata *ppd, int which, void *t);
 int fm_set_table(struct hfi1_pportdata *ppd, int which, void *t);
 
-void set_up_vl15(struct hfi1_devdata *dd, u8 vau, u16 vl15buf);
+void set_up_vau(struct hfi1_devdata *dd, u8 vau);
+void set_up_vl15(struct hfi1_devdata *dd, u16 vl15buf);
 void reset_link_credits(struct hfi1_devdata *dd);
 void assign_remote_cm_au_table(struct hfi1_devdata *dd, u8 vcu);
 
diff --git a/drivers/infiniband/hw/hfi1/intr.c b/drivers/infiniband/hw/hfi1/intr.c
index ba265d0ae93b..04a5082d5ac5 100644
--- a/drivers/infiniband/hw/hfi1/intr.c
+++ b/drivers/infiniband/hw/hfi1/intr.c
@@ -130,7 +130,8 @@ void handle_linkup_change(struct hfi1_devdata *dd, u32 linkup)
                  * the remote values.  Both sides must be using the values.
                  */
                 if (quick_linkup || dd->icode == ICODE_FUNCTIONAL_SIMULATOR) {
-                        set_up_vl15(dd, dd->vau, dd->vl15_init);
+                        set_up_vau(dd, dd->vau);
+                        set_up_vl15(dd, dd->vl15_init);
                         assign_remote_cm_au_table(dd, dd->vcu);
                 }