[PATCH v3] powerpc/mce: Remove per cpu variables from MCE handlers

* [PATCH v3] powerpc/mce: Remove per cpu variables from MCE handlers
@ 2021-01-15 12:58 Ganesh Goudar
  2021-01-19  3:58 ` Nicholas Piggin
  0 siblings, 1 reply; 3+ messages in thread
From: Ganesh Goudar @ 2021-01-15 12:58 UTC (permalink / raw)
  To: linuxppc-dev, mpe; +Cc: Ganesh Goudar, mahesh, npiggin

Access to per-cpu variables requires translation to be enabled on
pseries machine running in hash mmu mode, Since part of MCE handler
runs in realmode and part of MCE handling code is shared between ppc
architectures pseries and powernv, it becomes difficult to manage
these variables differently on different architectures, So have
these variables in paca instead of having them as per-cpu variables
to avoid complications.

Maximum recursive depth of MCE is 4, Considering the maximum depth
allowed reduce the size of event to 10 from 100.

Signed-off-by: Ganesh Goudar <ganeshgr@linux.ibm.com>
---
v2: Dynamically allocate memory for machine check event info

v3: Remove check for hash mmu lpar, use memblock_alloc_try_nid
    to allocate memory.
---
 arch/powerpc/include/asm/mce.h     | 21 ++++++++-
 arch/powerpc/include/asm/paca.h    |  4 ++
 arch/powerpc/kernel/mce.c          | 76 +++++++++++++++++-------------
 arch/powerpc/kernel/setup-common.c |  2 +-
 4 files changed, 69 insertions(+), 34 deletions(-)

diff --git a/arch/powerpc/include/asm/mce.h b/arch/powerpc/include/asm/mce.h
index e6c27ae843dc..8d6e3a7a9f37 100644
--- a/arch/powerpc/include/asm/mce.h
+++ b/arch/powerpc/include/asm/mce.h
@@ -204,7 +204,18 @@ struct mce_error_info {
 	bool			ignore_event;
 };
 
-#define MAX_MC_EVT	100
+#define MAX_MC_EVT	10
+
+struct mce_info {
+	int mce_nest_count;
+	struct machine_check_event mce_event[MAX_MC_EVT];
+	/* Queue for delayed MCE events. */
+	int mce_queue_count;
+	struct machine_check_event mce_event_queue[MAX_MC_EVT];
+	/* Queue for delayed MCE UE events. */
+	int mce_ue_count;
+	struct machine_check_event  mce_ue_event_queue[MAX_MC_EVT];
+};
 
 /* Release flags for get_mce_event() */
 #define MCE_EVENT_RELEASE	true
@@ -233,5 +244,13 @@ long __machine_check_early_realmode_p7(struct pt_regs *regs);
 long __machine_check_early_realmode_p8(struct pt_regs *regs);
 long __machine_check_early_realmode_p9(struct pt_regs *regs);
 long __machine_check_early_realmode_p10(struct pt_regs *regs);
+#define get_mce_info() local_paca->mce_info
+#endif /* CONFIG_PPC_BOOK3S_64 */
+
+#ifdef CONFIG_PPC_BOOK3S_64
+void mce_init(void);
+#else
+static inline void mce_init(void) { };
 #endif /* CONFIG_PPC_BOOK3S_64 */
+
 #endif /* __ASM_PPC64_MCE_H__ */
diff --git a/arch/powerpc/include/asm/paca.h b/arch/powerpc/include/asm/paca.h
index 9454d29ff4b4..38e0c55e845d 100644
--- a/arch/powerpc/include/asm/paca.h
+++ b/arch/powerpc/include/asm/paca.h
@@ -29,6 +29,7 @@
 #include <asm/hmi.h>
 #include <asm/cpuidle.h>
 #include <asm/atomic.h>
+#include <asm/mce.h>
 
 #include <asm-generic/mmiowb_types.h>
 
@@ -273,6 +274,9 @@ struct paca_struct {
 #ifdef CONFIG_MMIOWB
 	struct mmiowb_state mmiowb_state;
 #endif
+#ifdef CONFIG_PPC_BOOK3S_64
+	struct mce_info *mce_info;
+#endif /* CONFIG_PPC_BOOK3S_64 */
 } ____cacheline_aligned;
 
 extern void copy_mm_to_paca(struct mm_struct *mm);
diff --git a/arch/powerpc/kernel/mce.c b/arch/powerpc/kernel/mce.c
index 9f3e133b57b7..feeb3231b541 100644
--- a/arch/powerpc/kernel/mce.c
+++ b/arch/powerpc/kernel/mce.c
@@ -17,22 +17,13 @@
 #include <linux/irq_work.h>
 #include <linux/extable.h>
 #include <linux/ftrace.h>
+#include <linux/memblock.h>
 
 #include <asm/machdep.h>
 #include <asm/mce.h>
 #include <asm/nmi.h>
 
-static DEFINE_PER_CPU(int, mce_nest_count);
-static DEFINE_PER_CPU(struct machine_check_event[MAX_MC_EVT], mce_event);
-
-/* Queue for delayed MCE events. */
-static DEFINE_PER_CPU(int, mce_queue_count);
-static DEFINE_PER_CPU(struct machine_check_event[MAX_MC_EVT], mce_event_queue);
-
-/* Queue for delayed MCE UE events. */
-static DEFINE_PER_CPU(int, mce_ue_count);
-static DEFINE_PER_CPU(struct machine_check_event[MAX_MC_EVT],
-					mce_ue_event_queue);
+#include "setup.h"
 
 static void machine_check_process_queued_event(struct irq_work *work);
 static void machine_check_ue_irq_work(struct irq_work *work);
@@ -103,8 +94,8 @@ void save_mce_event(struct pt_regs *regs, long handled,
 		    struct mce_error_info *mce_err,
 		    uint64_t nip, uint64_t addr, uint64_t phys_addr)
 {
-	int index = __this_cpu_inc_return(mce_nest_count) - 1;
-	struct machine_check_event *mce = this_cpu_ptr(&mce_event[index]);
+	int index = get_mce_info()->mce_nest_count++;
+	struct machine_check_event *mce = &get_mce_info()->mce_event[index];
 
 	/*
 	 * Return if we don't have enough space to log mce event.
@@ -191,7 +182,7 @@ void save_mce_event(struct pt_regs *regs, long handled,
  */
 int get_mce_event(struct machine_check_event *mce, bool release)
 {
-	int index = __this_cpu_read(mce_nest_count) - 1;
+	int index = get_mce_info()->mce_nest_count - 1;
 	struct machine_check_event *mc_evt;
 	int ret = 0;
 
@@ -201,7 +192,7 @@ int get_mce_event(struct machine_check_event *mce, bool release)
 
 	/* Check if we have MCE info to process. */
 	if (index < MAX_MC_EVT) {
-		mc_evt = this_cpu_ptr(&mce_event[index]);
+		mc_evt = &get_mce_info()->mce_event[index];
 		/* Copy the event structure and release the original */
 		if (mce)
 			*mce = *mc_evt;
@@ -211,7 +202,7 @@ int get_mce_event(struct machine_check_event *mce, bool release)
 	}
 	/* Decrement the count to free the slot. */
 	if (release)
-		__this_cpu_dec(mce_nest_count);
+		get_mce_info()->mce_nest_count--;
 
 	return ret;
 }
@@ -233,13 +224,13 @@ static void machine_check_ue_event(struct machine_check_event *evt)
 {
 	int index;
 
-	index = __this_cpu_inc_return(mce_ue_count) - 1;
+	index = get_mce_info()->mce_ue_count++;
 	/* If queue is full, just return for now. */
 	if (index >= MAX_MC_EVT) {
-		__this_cpu_dec(mce_ue_count);
+		get_mce_info()->mce_ue_count--;
 		return;
 	}
-	memcpy(this_cpu_ptr(&mce_ue_event_queue[index]), evt, sizeof(*evt));
+	memcpy(&get_mce_info()->mce_ue_event_queue[index], evt, sizeof(*evt));
 
 	/* Queue work to process this event later. */
 	irq_work_queue(&mce_ue_event_irq_work);
@@ -256,13 +247,13 @@ void machine_check_queue_event(void)
 	if (!get_mce_event(&evt, MCE_EVENT_RELEASE))
 		return;
 
-	index = __this_cpu_inc_return(mce_queue_count) - 1;
+	index = get_mce_info()->mce_queue_count++;
 	/* If queue is full, just return for now. */
 	if (index >= MAX_MC_EVT) {
-		__this_cpu_dec(mce_queue_count);
+		get_mce_info()->mce_queue_count--;
 		return;
 	}
-	memcpy(this_cpu_ptr(&mce_event_queue[index]), &evt, sizeof(evt));
+	memcpy(&get_mce_info()->mce_event_queue[index], &evt, sizeof(evt));
 
 	/* Queue irq work to process this event later. */
 	irq_work_queue(&mce_event_process_work);
@@ -289,9 +280,9 @@ static void machine_process_ue_event(struct work_struct *work)
 	int index;
 	struct machine_check_event *evt;
 
-	while (__this_cpu_read(mce_ue_count) > 0) {
-		index = __this_cpu_read(mce_ue_count) - 1;
-		evt = this_cpu_ptr(&mce_ue_event_queue[index]);
+	while (get_mce_info()->mce_ue_count > 0) {
+		index = get_mce_info()->mce_ue_count - 1;
+		evt = &get_mce_info()->mce_ue_event_queue[index];
 		blocking_notifier_call_chain(&mce_notifier_list, 0, evt);
 #ifdef CONFIG_MEMORY_FAILURE
 		/*
@@ -304,7 +295,7 @@ static void machine_process_ue_event(struct work_struct *work)
 		 */
 		if (evt->error_type == MCE_ERROR_TYPE_UE) {
 			if (evt->u.ue_error.ignore_event) {
-				__this_cpu_dec(mce_ue_count);
+				get_mce_info()->mce_ue_count--;
 				continue;
 			}
 
@@ -320,7 +311,7 @@ static void machine_process_ue_event(struct work_struct *work)
 					"was generated\n");
 		}
 #endif
-		__this_cpu_dec(mce_ue_count);
+		get_mce_info()->mce_ue_count--;
 	}
 }
 /*
@@ -338,17 +329,17 @@ static void machine_check_process_queued_event(struct irq_work *work)
 	 * For now just print it to console.
 	 * TODO: log this error event to FSP or nvram.
 	 */
-	while (__this_cpu_read(mce_queue_count) > 0) {
-		index = __this_cpu_read(mce_queue_count) - 1;
-		evt = this_cpu_ptr(&mce_event_queue[index]);
+	while (get_mce_info()->mce_queue_count > 0) {
+		index = get_mce_info()->mce_queue_count - 1;
+		evt = &get_mce_info()->mce_event_queue[index];
 
 		if (evt->error_type == MCE_ERROR_TYPE_UE &&
 		    evt->u.ue_error.ignore_event) {
-			__this_cpu_dec(mce_queue_count);
+			get_mce_info()->mce_queue_count--;
 			continue;
 		}
 		machine_check_print_event_info(evt, false, false);
-		__this_cpu_dec(mce_queue_count);
+		get_mce_info()->mce_queue_count--;
 	}
 }
 
@@ -741,3 +732,24 @@ long hmi_exception_realmode(struct pt_regs *regs)
 
 	return 1;
 }
+
+void __init mce_init(void)
+{
+	struct mce_info *mce_info;
+	u64 limit;
+	int i;
+
+	limit = min(ppc64_bolted_size(), ppc64_rma_size);
+	for_each_possible_cpu(i) {
+		mce_info = memblock_alloc_try_nid(sizeof(*mce_info),
+						  __alignof__(*mce_info),
+						  MEMBLOCK_LOW_LIMIT,
+						  limit, cpu_to_node(i));
+		if (!mce_info)
+			goto err;
+		paca_ptrs[i]->mce_info = mce_info;
+	}
+	return;
+err:
+	panic("Failed to allocate memory for MCE event data\n");
+}
diff --git a/arch/powerpc/kernel/setup-common.c b/arch/powerpc/kernel/setup-common.c
index 71f38e9248be..17dc451f0e45 100644
--- a/arch/powerpc/kernel/setup-common.c
+++ b/arch/powerpc/kernel/setup-common.c
@@ -916,7 +916,6 @@ void __init setup_arch(char **cmdline_p)
 	/* On BookE, setup per-core TLB data structures. */
 	setup_tlb_core_data();
 #endif
-
 	/* Print various info about the machine that has been gathered so far. */
 	print_system_info();
 
@@ -938,6 +937,7 @@ void __init setup_arch(char **cmdline_p)
 	exc_lvl_early_init();
 	emergency_stack_init();
 
+	mce_init();
 	smp_release_cpus();
 
 	initmem_init();
-- 
2.26.2


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