[PATCH v3 01/12] ACPI / APEI: Move the estatus queue code up, and under its own ifdef

[James Morse <james.morse@arm.com>]

To support asynchronous NMI-like notifications on arm64 we need to use
the estatus-queue. These patches refactor it to allow multiple APEI
notification types to use it.

First we move the estatus-queue code higher in the file so that any
notify_foo() handler can make use of it.

This patch moves code around ... and makes the following trivial change:
Freshen the dated comment above ghes_estatus_llist. printk() is no
longer the issue, its the helpers like memory_failure_queue() that
still aren't nmi safe.

Signed-off-by: James Morse <james.morse@arm.com>
Reviewed-by: Punit Agrawal <punit.agrawal@arm.com>

Notes for cover letter:
ghes.c has three things all called 'estatus'. One is a pool of memory
that has a static size, and is grown/shrunk when new NMI users are
allocated.
The second is the cache, this holds recent notifications so we can
suppress notifications we've already handled.
The last is the queue, which hold data from NMI notifications (in pool
memory) that can't be handled immediatly.
---
 drivers/acpi/apei/ghes.c | 265 ++++++++++++++++++++++++-----------------------
 1 file changed, 137 insertions(+), 128 deletions(-)

diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
index 1efefe919555..e2af91c92135 100644
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c
@@ -545,6 +545,16 @@ static int ghes_print_estatus(const char *pfx,
 	return 0;
 }
 
+static void __ghes_panic(struct ghes *ghes)
+{
+	__ghes_print_estatus(KERN_EMERG, ghes->generic, ghes->estatus);
+
+	/* reboot to log the error! */
+	if (!panic_timeout)
+		panic_timeout = ghes_panic_timeout;
+	panic("Fatal hardware error!");
+}
+
 /*
  * GHES error status reporting throttle, to report more kinds of
  * errors, instead of just most frequently occurred errors.
@@ -672,6 +682,133 @@ static void ghes_estatus_cache_add(
 	rcu_read_unlock();
 }
 
+#ifdef CONFIG_HAVE_ACPI_APEI_NMI
+/*
+ * Handlers for CPER records may not be NMI safe. For example,
+ * memory_failure_queue() takes spinlocks and calls schedule_work_on().
+ * In any NMI-like handler, memory from ghes_estatus_pool is used to save
+ * estatus, and added to the ghes_estatus_llist. irq_work_queue() causes
+ * ghes_proc_in_irq() to run in IRQ context where each estatus in
+ * ghes_estatus_llist is processed. Each NMI-like error source must grow
+ * the ghes_estatus_pool to ensure memory is available.
+ *
+ * Memory from the ghes_estatus_pool is also used with the ghes_estatus_cache
+ * to suppress frequent messages.
+ */
+static struct llist_head ghes_estatus_llist;
+static struct irq_work ghes_proc_irq_work;
+
+static void ghes_print_queued_estatus(void)
+{
+	struct llist_node *llnode;
+	struct ghes_estatus_node *estatus_node;
+	struct acpi_hest_generic *generic;
+	struct acpi_hest_generic_status *estatus;
+
+	llnode = llist_del_all(&ghes_estatus_llist);
+	/*
+	 * Because the time order of estatus in list is reversed,
+	 * revert it back to proper order.
+	 */
+	llnode = llist_reverse_order(llnode);
+	while (llnode) {
+		estatus_node = llist_entry(llnode, struct ghes_estatus_node,
+					   llnode);
+		estatus = GHES_ESTATUS_FROM_NODE(estatus_node);
+		generic = estatus_node->generic;
+		ghes_print_estatus(NULL, generic, estatus);
+		llnode = llnode->next;
+	}
+}
+
+/* Save estatus for further processing in IRQ context */
+static void __process_error(struct ghes *ghes)
+{
+#ifdef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
+	u32 len, node_len;
+	struct ghes_estatus_node *estatus_node;
+	struct acpi_hest_generic_status *estatus;
+
+	if (ghes_estatus_cached(ghes->estatus))
+		return;
+
+	len = cper_estatus_len(ghes->estatus);
+	node_len = GHES_ESTATUS_NODE_LEN(len);
+
+	estatus_node = (void *)gen_pool_alloc(ghes_estatus_pool, node_len);
+	if (!estatus_node)
+		return;
+
+	estatus_node->ghes = ghes;
+	estatus_node->generic = ghes->generic;
+	estatus = GHES_ESTATUS_FROM_NODE(estatus_node);
+	memcpy(estatus, ghes->estatus, len);
+	llist_add(&estatus_node->llnode, &ghes_estatus_llist);
+#endif
+}
+
+static unsigned long ghes_esource_prealloc_size(
+	const struct acpi_hest_generic *generic)
+{
+	unsigned long block_length, prealloc_records, prealloc_size;
+
+	block_length = min_t(unsigned long, generic->error_block_length,
+			     GHES_ESTATUS_MAX_SIZE);
+	prealloc_records = max_t(unsigned long,
+				 generic->records_to_preallocate, 1);
+	prealloc_size = min_t(unsigned long, block_length * prealloc_records,
+			      GHES_ESOURCE_PREALLOC_MAX_SIZE);
+
+	return prealloc_size;
+}
+
+static void ghes_estatus_pool_shrink(unsigned long len)
+{
+	ghes_estatus_pool_size_request -= PAGE_ALIGN(len);
+}
+
+static void ghes_proc_in_irq(struct irq_work *irq_work)
+{
+	struct llist_node *llnode, *next;
+	struct ghes_estatus_node *estatus_node;
+	struct acpi_hest_generic *generic;
+	struct acpi_hest_generic_status *estatus;
+	u32 len, node_len;
+
+	llnode = llist_del_all(&ghes_estatus_llist);
+	/*
+	 * Because the time order of estatus in list is reversed,
+	 * revert it back to proper order.
+	 */
+	llnode = llist_reverse_order(llnode);
+	while (llnode) {
+		next = llnode->next;
+		estatus_node = llist_entry(llnode, struct ghes_estatus_node,
+					   llnode);
+		estatus = GHES_ESTATUS_FROM_NODE(estatus_node);
+		len = cper_estatus_len(estatus);
+		node_len = GHES_ESTATUS_NODE_LEN(len);
+		ghes_do_proc(estatus_node->ghes, estatus);
+		if (!ghes_estatus_cached(estatus)) {
+			generic = estatus_node->generic;
+			if (ghes_print_estatus(NULL, generic, estatus))
+				ghes_estatus_cache_add(generic, estatus);
+		}
+		gen_pool_free(ghes_estatus_pool, (unsigned long)estatus_node,
+			      node_len);
+		llnode = next;
+	}
+}
+
+static void ghes_nmi_init_cxt(void)
+{
+	init_irq_work(&ghes_proc_irq_work, ghes_proc_in_irq);
+}
+
+#else
+static inline void ghes_nmi_init_cxt(void) { }
+#endif /* CONFIG_HAVE_ACPI_APEI_NMI */
+
 static int ghes_ack_error(struct acpi_hest_generic_v2 *gv2)
 {
 	int rc;
@@ -687,16 +824,6 @@ static int ghes_ack_error(struct acpi_hest_generic_v2 *gv2)
 	return apei_write(val, &gv2->read_ack_register);
 }
 
-static void __ghes_panic(struct ghes *ghes)
-{
-	__ghes_print_estatus(KERN_EMERG, ghes->generic, ghes->estatus);
-
-	/* reboot to log the error! */
-	if (!panic_timeout)
-		panic_timeout = ghes_panic_timeout;
-	panic("Fatal hardware error!");
-}
-
 static int ghes_proc(struct ghes *ghes)
 {
 	int rc;
@@ -828,17 +955,6 @@ static inline void ghes_sea_remove(struct ghes *ghes) { }
 #endif /* CONFIG_ACPI_APEI_SEA */
 
 #ifdef CONFIG_HAVE_ACPI_APEI_NMI
-/*
- * printk is not safe in NMI context.  So in NMI handler, we allocate
- * required memory from lock-less memory allocator
- * (ghes_estatus_pool), save estatus into it, put them into lock-less
- * list (ghes_estatus_llist), then delay printk into IRQ context via
- * irq_work (ghes_proc_irq_work).  ghes_estatus_size_request record
- * required pool size by all NMI error source.
- */
-static struct llist_head ghes_estatus_llist;
-static struct irq_work ghes_proc_irq_work;
-
 /*
  * NMI may be triggered on any CPU, so ghes_in_nmi is used for
  * having only one concurrent reader.
@@ -847,88 +963,6 @@ static atomic_t ghes_in_nmi = ATOMIC_INIT(0);
 
 static LIST_HEAD(ghes_nmi);
 
-static void ghes_proc_in_irq(struct irq_work *irq_work)
-{
-	struct llist_node *llnode, *next;
-	struct ghes_estatus_node *estatus_node;
-	struct acpi_hest_generic *generic;
-	struct acpi_hest_generic_status *estatus;
-	u32 len, node_len;
-
-	llnode = llist_del_all(&ghes_estatus_llist);
-	/*
-	 * Because the time order of estatus in list is reversed,
-	 * revert it back to proper order.
-	 */
-	llnode = llist_reverse_order(llnode);
-	while (llnode) {
-		next = llnode->next;
-		estatus_node = llist_entry(llnode, struct ghes_estatus_node,
-					   llnode);
-		estatus = GHES_ESTATUS_FROM_NODE(estatus_node);
-		len = cper_estatus_len(estatus);
-		node_len = GHES_ESTATUS_NODE_LEN(len);
-		ghes_do_proc(estatus_node->ghes, estatus);
-		if (!ghes_estatus_cached(estatus)) {
-			generic = estatus_node->generic;
-			if (ghes_print_estatus(NULL, generic, estatus))
-				ghes_estatus_cache_add(generic, estatus);
-		}
-		gen_pool_free(ghes_estatus_pool, (unsigned long)estatus_node,
-			      node_len);
-		llnode = next;
-	}
-}
-
-static void ghes_print_queued_estatus(void)
-{
-	struct llist_node *llnode;
-	struct ghes_estatus_node *estatus_node;
-	struct acpi_hest_generic *generic;
-	struct acpi_hest_generic_status *estatus;
-
-	llnode = llist_del_all(&ghes_estatus_llist);
-	/*
-	 * Because the time order of estatus in list is reversed,
-	 * revert it back to proper order.
-	 */
-	llnode = llist_reverse_order(llnode);
-	while (llnode) {
-		estatus_node = llist_entry(llnode, struct ghes_estatus_node,
-					   llnode);
-		estatus = GHES_ESTATUS_FROM_NODE(estatus_node);
-		generic = estatus_node->generic;
-		ghes_print_estatus(NULL, generic, estatus);
-		llnode = llnode->next;
-	}
-}
-
-/* Save estatus for further processing in IRQ context */
-static void __process_error(struct ghes *ghes)
-{
-#ifdef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
-	u32 len, node_len;
-	struct ghes_estatus_node *estatus_node;
-	struct acpi_hest_generic_status *estatus;
-
-	if (ghes_estatus_cached(ghes->estatus))
-		return;
-
-	len = cper_estatus_len(ghes->estatus);
-	node_len = GHES_ESTATUS_NODE_LEN(len);
-
-	estatus_node = (void *)gen_pool_alloc(ghes_estatus_pool, node_len);
-	if (!estatus_node)
-		return;
-
-	estatus_node->ghes = ghes;
-	estatus_node->generic = ghes->generic;
-	estatus = GHES_ESTATUS_FROM_NODE(estatus_node);
-	memcpy(estatus, ghes->estatus, len);
-	llist_add(&estatus_node->llnode, &ghes_estatus_llist);
-#endif
-}
-
 static int ghes_notify_nmi(unsigned int cmd, struct pt_regs *regs)
 {
 	struct ghes *ghes;
@@ -967,26 +1001,6 @@ static int ghes_notify_nmi(unsigned int cmd, struct pt_regs *regs)
 	return ret;
 }
 
-static unsigned long ghes_esource_prealloc_size(
-	const struct acpi_hest_generic *generic)
-{
-	unsigned long block_length, prealloc_records, prealloc_size;
-
-	block_length = min_t(unsigned long, generic->error_block_length,
-			     GHES_ESTATUS_MAX_SIZE);
-	prealloc_records = max_t(unsigned long,
-				 generic->records_to_preallocate, 1);
-	prealloc_size = min_t(unsigned long, block_length * prealloc_records,
-			      GHES_ESOURCE_PREALLOC_MAX_SIZE);
-
-	return prealloc_size;
-}
-
-static void ghes_estatus_pool_shrink(unsigned long len)
-{
-	ghes_estatus_pool_size_request -= PAGE_ALIGN(len);
-}
-
 static void ghes_nmi_add(struct ghes *ghes)
 {
 	unsigned long len;
@@ -1018,14 +1032,9 @@ static void ghes_nmi_remove(struct ghes *ghes)
 	ghes_estatus_pool_shrink(len);
 }
 
-static void ghes_nmi_init_cxt(void)
-{
-	init_irq_work(&ghes_proc_irq_work, ghes_proc_in_irq);
-}
 #else /* CONFIG_HAVE_ACPI_APEI_NMI */
 static inline void ghes_nmi_add(struct ghes *ghes) { }
 static inline void ghes_nmi_remove(struct ghes *ghes) { }
-static inline void ghes_nmi_init_cxt(void) { }
 #endif /* CONFIG_HAVE_ACPI_APEI_NMI */
 
 static int ghes_probe(struct platform_device *ghes_dev)
-- 
2.16.2