powerpc/pseries: Move dtl scanning and steal time accounting to pseries platform

dtl is the PAPR Dispatch Trace Log, which is entirely a pseries feature.
The pseries platform alrady has a file dealing with the dtl, so move
scanning for stolen time accounting there from kernel/time.c.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220902085316.2071519-5-npiggin@gmail.com

arch/powerpc/include/asm/cputime.h

@@ -95,7 +95,7 @@ static notrace inline void account_stolen_time(void)
 		struct lppaca *lp = local_paca->lppaca_ptr;
 
 		if (unlikely(local_paca->dtl_ridx != be64_to_cpu(lp->dtl_idx)))
-			accumulate_stolen_time();
+			pseries_accumulate_stolen_time();
 	}
 #endif
 }

arch/powerpc/include/asm/dtl.h

@@ -37,14 +37,6 @@ struct dtl_entry {
 extern struct kmem_cache *dtl_cache;
 extern rwlock_t dtl_access_lock;
 
-/*
- * When CONFIG_VIRT_CPU_ACCOUNTING_NATIVE = y, the cpu accounting code controls
- * reading from the dispatch trace log.  If other code wants to consume
- * DTL entries, it can set this pointer to a function that will get
- * called once for each DTL entry that gets processed.
- */
-extern void (*dtl_consumer)(struct dtl_entry *entry, u64 index);
-
 extern void register_dtl_buffer(int cpu);
 extern void alloc_dtl_buffers(unsigned long *time_limit);
 extern long hcall_vphn(unsigned long cpu, u64 flags, __be32 *associativity);

arch/powerpc/include/asm/time.h

@@ -116,8 +116,9 @@ unsigned long long tb_to_ns(unsigned long long tb_ticks);
 
 void timer_broadcast_interrupt(void);
 
-/* SPLPAR */
-void accumulate_stolen_time(void);
+/* SPLPAR and VIRT_CPU_ACCOUNTING_NATIVE */
+void pseries_accumulate_stolen_time(void);
+u64 pseries_calculate_stolen_time(u64 stop_tb);
 
 #endif /* __KERNEL__ */
 #endif /* __POWERPC_TIME_H */

arch/powerpc/kernel/time.c

@@ -178,92 +178,6 @@ static inline unsigned long read_spurr(unsigned long tb)
 	return tb;
 }
 
-#ifdef CONFIG_PPC_SPLPAR
-
-#include <asm/dtl.h>
-
-void (*dtl_consumer)(struct dtl_entry *, u64);
-
-/*
- * Scan the dispatch trace log and count up the stolen time.
- * Should be called with interrupts disabled.
- */
-static u64 scan_dispatch_log(u64 stop_tb)
-{
-	u64 i = local_paca->dtl_ridx;
-	struct dtl_entry *dtl = local_paca->dtl_curr;
-	struct dtl_entry *dtl_end = local_paca->dispatch_log_end;
-	struct lppaca *vpa = local_paca->lppaca_ptr;
-	u64 tb_delta;
-	u64 stolen = 0;
-	u64 dtb;
-
-	if (!dtl)
-		return 0;
-
-	if (i == be64_to_cpu(vpa->dtl_idx))
-		return 0;
-	while (i < be64_to_cpu(vpa->dtl_idx)) {
-		dtb = be64_to_cpu(dtl->timebase);
-		tb_delta = be32_to_cpu(dtl->enqueue_to_dispatch_time) +
-			be32_to_cpu(dtl->ready_to_enqueue_time);
-		barrier();
-		if (i + N_DISPATCH_LOG < be64_to_cpu(vpa->dtl_idx)) {
-			/* buffer has overflowed */
-			i = be64_to_cpu(vpa->dtl_idx) - N_DISPATCH_LOG;
-			dtl = local_paca->dispatch_log + (i % N_DISPATCH_LOG);
-			continue;
-		}
-		if (dtb > stop_tb)
-			break;
-		if (dtl_consumer)
-			dtl_consumer(dtl, i);
-		stolen += tb_delta;
-		++i;
-		++dtl;
-		if (dtl == dtl_end)
-			dtl = local_paca->dispatch_log;
-	}
-	local_paca->dtl_ridx = i;
-	local_paca->dtl_curr = dtl;
-	return stolen;
-}
-
-/*
- * Accumulate stolen time by scanning the dispatch trace log.
- * Called on entry from user mode.
- */
-void notrace accumulate_stolen_time(void)
-{
-	u64 sst, ust;
-	struct cpu_accounting_data *acct = &local_paca->accounting;
-
-	sst = scan_dispatch_log(acct->starttime_user);
-	ust = scan_dispatch_log(acct->starttime);
-	acct->stime -= sst;
-	acct->utime -= ust;
-	acct->steal_time += ust + sst;
-}
-
-static inline u64 calculate_stolen_time(u64 stop_tb)
-{
-	if (!firmware_has_feature(FW_FEATURE_SPLPAR))
-		return 0;
-
-	if (get_paca()->dtl_ridx != be64_to_cpu(get_lppaca()->dtl_idx))
-		return scan_dispatch_log(stop_tb);
-
-	return 0;
-}
-
-#else /* CONFIG_PPC_SPLPAR */
-static inline u64 calculate_stolen_time(u64 stop_tb)
-{
-	return 0;
-}
-
-#endif /* CONFIG_PPC_SPLPAR */
-
 /*
  * Account time for a transition between system, hard irq
  * or soft irq state.
@@ -322,7 +236,11 @@ static unsigned long vtime_delta(struct cpu_accounting_data *acct,
 
 	*stime_scaled = vtime_delta_scaled(acct, now, stime);
 
-	*steal_time = calculate_stolen_time(now);
+	if (IS_ENABLED(CONFIG_PPC_SPLPAR) &&
+			firmware_has_feature(FW_FEATURE_SPLPAR))
+		*steal_time = pseries_calculate_stolen_time(now);
+	else
+		*steal_time = 0;
 
 	return stime;
 }

arch/powerpc/platforms/pseries/dtl.c

@@ -37,6 +37,15 @@ static u8 dtl_event_mask = DTL_LOG_ALL;
 static int dtl_buf_entries = N_DISPATCH_LOG;
 
 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
+
+/*
+ * When CONFIG_VIRT_CPU_ACCOUNTING_NATIVE = y, the cpu accounting code controls
+ * reading from the dispatch trace log.  If other code wants to consume
+ * DTL entries, it can set this pointer to a function that will get
+ * called once for each DTL entry that gets processed.
+ */
+static void (*dtl_consumer)(struct dtl_entry *entry, u64 index);
+
 struct dtl_ring {
 	u64	write_index;
 	struct dtl_entry *write_ptr;
@@ -48,6 +57,78 @@ static DEFINE_PER_CPU(struct dtl_ring, dtl_rings);
 
 static atomic_t dtl_count;
 
+/*
+ * Scan the dispatch trace log and count up the stolen time.
+ * Should be called with interrupts disabled.
+ */
+static notrace u64 scan_dispatch_log(u64 stop_tb)
+{
+	u64 i = local_paca->dtl_ridx;
+	struct dtl_entry *dtl = local_paca->dtl_curr;
+	struct dtl_entry *dtl_end = local_paca->dispatch_log_end;
+	struct lppaca *vpa = local_paca->lppaca_ptr;
+	u64 tb_delta;
+	u64 stolen = 0;
+	u64 dtb;
+
+	if (!dtl)
+		return 0;
+
+	if (i == be64_to_cpu(vpa->dtl_idx))
+		return 0;
+	while (i < be64_to_cpu(vpa->dtl_idx)) {
+		dtb = be64_to_cpu(dtl->timebase);
+		tb_delta = be32_to_cpu(dtl->enqueue_to_dispatch_time) +
+			be32_to_cpu(dtl->ready_to_enqueue_time);
+		barrier();
+		if (i + N_DISPATCH_LOG < be64_to_cpu(vpa->dtl_idx)) {
+			/* buffer has overflowed */
+			i = be64_to_cpu(vpa->dtl_idx) - N_DISPATCH_LOG;
+			dtl = local_paca->dispatch_log + (i % N_DISPATCH_LOG);
+			continue;
+		}
+		if (dtb > stop_tb)
+			break;
+		if (dtl_consumer)
+			dtl_consumer(dtl, i);
+		stolen += tb_delta;
+		++i;
+		++dtl;
+		if (dtl == dtl_end)
+			dtl = local_paca->dispatch_log;
+	}
+	local_paca->dtl_ridx = i;
+	local_paca->dtl_curr = dtl;
+	return stolen;
+}
+
+/*
+ * Accumulate stolen time by scanning the dispatch trace log.
+ * Called on entry from user mode.
+ */
+void notrace pseries_accumulate_stolen_time(void)
+{
+	u64 sst, ust;
+	struct cpu_accounting_data *acct = &local_paca->accounting;
+
+	sst = scan_dispatch_log(acct->starttime_user);
+	ust = scan_dispatch_log(acct->starttime);
+	acct->stime -= sst;
+	acct->utime -= ust;
+	acct->steal_time += ust + sst;
+}
+
+u64 pseries_calculate_stolen_time(u64 stop_tb)
+{
+	if (!firmware_has_feature(FW_FEATURE_SPLPAR))
+		return 0;
+
+	if (get_paca()->dtl_ridx != be64_to_cpu(get_lppaca()->dtl_idx))
+		return scan_dispatch_log(stop_tb);
+
+	return 0;
+}
+
 /*
  * The cpu accounting code controls the DTL ring buffer, and we get
  * given entries as they are processed.