x86, UV: Calculate BAU destination timeout

Calculate the Broadcast Assist Unit's destination timeout period from the
values in the relevant MMR's.

Store it in each cpu's per-cpu BAU structure so that a destination
timeout can be differentiated from a 'plugged' situation in which all
software ack resources are already allocated and a timeout is pending.
That case returns an immediate destination error.

Signed-off-by: Cliff Wickman <cpw@sgi.com>
Cc: gregkh@suse.de
LKML-Reference: <E1OJvNx-0004Zq-RK@eag09.americas.sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 47 insertions, 4 deletions

diff --git a/arch/x86/kernel/tlb_uv.c b/arch/x86/kernel/tlb_uv.c
index 7fea555929e2..5506836c4a82 100644
--- a/arch/x86/kernel/tlb_uv.c
+++ b/arch/x86/kernel/tlb_uv.c
@@ -30,6 +30,19 @@ struct msg_desc {
         struct bau_payload_queue_entry *va_queue_last;
 };
 
+/* timeouts in nanoseconds (indexed by UVH_AGING_PRESCALE_SEL urgency7 30:28) */
+static int timeout_base_ns[] = {
+                20,
+                160,
+                1280,
+                10240,
+                81920,
+                655360,
+                5242880,
+                167772160
+};
+static int timeout_us;
+
 #define UV_INTD_SOFT_ACK_TIMEOUT_PERIOD 0x000000000bUL
 
 static int uv_bau_max_concurrent __read_mostly;
@@ -423,7 +436,8 @@ static int uv_wait_completion(struct bau_desc *bau_desc,
                          * pending.  In that case hardware returns the
                          * ERROR that looks like a destination timeout.
                          */
-                        if (cycles_2_us(ttime - bcp->send_message) < BIOS_TO) {
+                        if (cycles_2_us(ttime - bcp->send_message) <
+                                                        timeout_us) {
                                 bcp->conseccompletes = 0;
                                 return FLUSH_RETRY_PLUGGED;
                         }
@@ -908,12 +922,12 @@ static void uv_ptc_seq_stop(struct seq_file *file, void *data)
 }
 
 static inline unsigned long long
-millisec_2_cycles(unsigned long millisec)
+microsec_2_cycles(unsigned long microsec)
 {
         unsigned long ns;
         unsigned long long cyc;
 
-        ns = millisec * 1000;
+        ns = microsec * 1000;
         cyc = (ns << CYC2NS_SCALE_FACTOR)/(per_cpu(cyc2ns, smp_processor_id()));
         return cyc;
 }
@@ -1259,6 +1273,33 @@ static void __init uv_init_uvhub(int uvhub, int vector)
 }
 
 /*
+ * We will set BAU_MISC_CONTROL with a timeout period.
+ * But the BIOS has set UVH_AGING_PRESCALE_SEL and UVH_TRANSACTION_TIMEOUT.
+ * So the destination timeout period has be be calculated from them.
+ */
+static int
+calculate_destination_timeout(void)
+{
+        unsigned long mmr_image;
+        int mult1;
+        int mult2;
+        int index;
+        int base;
+        int ret;
+        unsigned long ts_ns;
+
+        mult1 = UV_INTD_SOFT_ACK_TIMEOUT_PERIOD & BAU_MISC_CONTROL_MULT_MASK;
+        mmr_image = uv_read_local_mmr(UVH_AGING_PRESCALE_SEL);
+        index = (mmr_image >> BAU_URGENCY_7_SHIFT) & BAU_URGENCY_7_MASK;
+        mmr_image = uv_read_local_mmr(UVH_TRANSACTION_TIMEOUT);
+        mult2 = (mmr_image >> BAU_TRANS_SHIFT) & BAU_TRANS_MASK;
+        base = timeout_base_ns[index];
+        ts_ns = base * mult1 * mult2;
+        ret = ts_ns / 1000;
+        return ret;
+}
+
+/*
  * initialize the bau_control structure for each cpu
  */
 static void uv_init_per_cpu(int nuvhubs)
@@ -1286,6 +1327,8 @@ static void uv_init_per_cpu(int nuvhubs)
         };
         struct uvhub_desc *uvhub_descs;
 
+        timeout_us = calculate_destination_timeout();
+
         uvhub_descs = (struct uvhub_desc *)
                 kmalloc(nuvhubs * sizeof(struct uvhub_desc), GFP_KERNEL);
         memset(uvhub_descs, 0, nuvhubs * sizeof(struct uvhub_desc));
@@ -1301,7 +1344,7 @@ static void uv_init_per_cpu(int nuvhubs)
                 bdp->uvhub = uvhub;
                 bdp->pnode = pnode;
                 /* time interval to catch a hardware stay-busy bug */
-                bcp->timeout_interval = millisec_2_cycles(3);
+                bcp->timeout_interval = microsec_2_cycles(2*timeout_us);
                 /* kludge: assume uv_hub.h is constant */
                 socket = (cpu_physical_id(cpu)>>5)&1;
                 if (socket >= bdp->num_sockets)