ACPI, APEI, GHES, printk support for recoverable error via NMI

Some APEI GHES recoverable errors are reported via NMI, but printk is
not safe in NMI context.

To solve the issue, a lock-less memory allocator is used to allocate
memory in NMI handler, save the error record into the allocated
memory, put the error record into a lock-less list.  On the other
hand, an irq_work is used to delay the operation from NMI context to
IRQ context.  The irq_work IRQ handler will remove nodes from
lock-less list, printk the error record and do some further processing
include recovery operation, then free the memory.

Signed-off-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

2 files changed, 193 insertions, 18 deletions

diff --git a/drivers/acpi/apei/Kconfig b/drivers/acpi/apei/Kconfig
index 3f45dde17aec..35596eaaca17 100644
--- a/drivers/acpi/apei/Kconfig
+++ b/drivers/acpi/apei/Kconfig
@@ -13,6 +13,8 @@ config ACPI_APEI_GHES
         bool "APEI Generic Hardware Error Source"
         depends on ACPI_APEI && X86
         select ACPI_HED
+        select LLIST
+        select GENERIC_ALLOCATOR
         help
           Generic Hardware Error Source provides a way to report
           platform hardware errors (such as that from chipset). It
diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
index b1390a61cde1..d1a40218e17e 100644
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c
@@ -12,7 +12,7 @@
  * For more information about Generic Hardware Error Source, please
  * refer to ACPI Specification version 4.0, section 17.3.2.6
  *
- * Copyright 2010 Intel Corp.
+ * Copyright 2010,2011 Intel Corp.
  *   Author: Huang Ying <ying.huang@intel.com>
  *
  * This program is free software; you can redistribute it and/or
@@ -42,6 +42,9 @@
 #include <linux/mutex.h>
 #include <linux/ratelimit.h>
 #include <linux/vmalloc.h>
+#include <linux/irq_work.h>
+#include <linux/llist.h>
+#include <linux/genalloc.h>
 #include <acpi/apei.h>
 #include <acpi/atomicio.h>
 #include <acpi/hed.h>
@@ -53,6 +56,15 @@
 #define GHES_PFX        "GHES: "
 
 #define GHES_ESTATUS_MAX_SIZE           65536
+#define GHES_ESOURCE_PREALLOC_MAX_SIZE  65536
+
+#define GHES_ESTATUS_POOL_MIN_ALLOC_ORDER 3
+
+#define GHES_ESTATUS_NODE_LEN(estatus_len)                      \
+        (sizeof(struct ghes_estatus_node) + (estatus_len))
+#define GHES_ESTATUS_FROM_NODE(estatus_node)                            \
+        ((struct acpi_hest_generic_status *)                            \
+         ((struct ghes_estatus_node *)(estatus_node) + 1))
 
 /*
  * One struct ghes is created for each generic hardware error source.
@@ -77,6 +89,11 @@ struct ghes {
         };
 };
 
+struct ghes_estatus_node {
+        struct llist_node llnode;
+        struct acpi_hest_generic *generic;
+};
+
 int ghes_disable;
 module_param_named(disable, ghes_disable, bool, 0);
 
@@ -124,6 +141,19 @@ static struct vm_struct *ghes_ioremap_area;
 static DEFINE_RAW_SPINLOCK(ghes_ioremap_lock_nmi);
 static DEFINE_SPINLOCK(ghes_ioremap_lock_irq);
 
+/*
+ * 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 gen_pool *ghes_estatus_pool;
+static unsigned long ghes_estatus_pool_size_request;
+static struct llist_head ghes_estatus_llist;
+static struct irq_work ghes_proc_irq_work;
+
 static int ghes_ioremap_init(void)
 {
         ghes_ioremap_area = __get_vm_area(PAGE_SIZE * GHES_IOREMAP_PAGES,
@@ -183,6 +213,55 @@ static void ghes_iounmap_irq(void __iomem *vaddr_ptr)
         __flush_tlb_one(vaddr);
 }
 
+static int ghes_estatus_pool_init(void)
+{
+        ghes_estatus_pool = gen_pool_create(GHES_ESTATUS_POOL_MIN_ALLOC_ORDER, -1);
+        if (!ghes_estatus_pool)
+                return -ENOMEM;
+        return 0;
+}
+
+static void ghes_estatus_pool_free_chunk_page(struct gen_pool *pool,
+                                              struct gen_pool_chunk *chunk,
+                                              void *data)
+{
+        free_page(chunk->start_addr);
+}
+
+static void ghes_estatus_pool_exit(void)
+{
+        gen_pool_for_each_chunk(ghes_estatus_pool,
+                                ghes_estatus_pool_free_chunk_page, NULL);
+        gen_pool_destroy(ghes_estatus_pool);
+}
+
+static int ghes_estatus_pool_expand(unsigned long len)
+{
+        unsigned long i, pages, size, addr;
+        int ret;
+
+        ghes_estatus_pool_size_request += PAGE_ALIGN(len);
+        size = gen_pool_size(ghes_estatus_pool);
+        if (size >= ghes_estatus_pool_size_request)
+                return 0;
+        pages = (ghes_estatus_pool_size_request - size) / PAGE_SIZE;
+        for (i = 0; i < pages; i++) {
+                addr = __get_free_page(GFP_KERNEL);
+                if (!addr)
+                        return -ENOMEM;
+                ret = gen_pool_add(ghes_estatus_pool, addr, PAGE_SIZE, -1);
+                if (ret)
+                        return ret;
+        }
+
+        return 0;
+}
+
+static void ghes_estatus_pool_shrink(unsigned long len)
+{
+        ghes_estatus_pool_size_request -= PAGE_ALIGN(len);
+}
+
 static struct ghes *ghes_new(struct acpi_hest_generic *generic)
 {
         struct ghes *ghes;
@@ -344,13 +423,13 @@ static void ghes_clear_estatus(struct ghes *ghes)
         ghes->flags &= ~GHES_TO_CLEAR;
 }
 
-static void ghes_do_proc(struct ghes *ghes)
+static void ghes_do_proc(const struct acpi_hest_generic_status *estatus)
 {
         int sev, processed = 0;
         struct acpi_hest_generic_data *gdata;
 
-        sev = ghes_severity(ghes->estatus->error_severity);
-        apei_estatus_for_each_section(ghes->estatus, gdata) {
+        sev = ghes_severity(estatus->error_severity);
+        apei_estatus_for_each_section(estatus, gdata) {
 #ifdef CONFIG_X86_MCE
                 if (!uuid_le_cmp(*(uuid_le *)gdata->section_type,
                                  CPER_SEC_PLATFORM_MEM)) {
@@ -363,27 +442,37 @@ static void ghes_do_proc(struct ghes *ghes)
         }
 }
 
-static void __ghes_print_estatus(const char *pfx, struct ghes *ghes)
+static void __ghes_print_estatus(const char *pfx,
+                                 const struct acpi_hest_generic *generic,
+                                 const struct acpi_hest_generic_status *estatus)
 {
         if (pfx == NULL) {
-                if (ghes_severity(ghes->estatus->error_severity) <=
+                if (ghes_severity(estatus->error_severity) <=
                     GHES_SEV_CORRECTED)
                         pfx = KERN_WARNING HW_ERR;
                 else
                         pfx = KERN_ERR HW_ERR;
         }
         printk("%s""Hardware error from APEI Generic Hardware Error Source: %d\n",
-               pfx, ghes->generic->header.source_id);
-        apei_estatus_print(pfx, ghes->estatus);
+               pfx, generic->header.source_id);
+        apei_estatus_print(pfx, estatus);
 }
 
-static void ghes_print_estatus(const char *pfx, struct ghes *ghes)
+static void ghes_print_estatus(const char *pfx,
+                               const struct acpi_hest_generic *generic,
+                               const struct acpi_hest_generic_status *estatus)
 {
         /* Not more than 2 messages every 5 seconds */
-        static DEFINE_RATELIMIT_STATE(ratelimit, 5*HZ, 2);
+        static DEFINE_RATELIMIT_STATE(ratelimit_corrected, 5*HZ, 2);
+        static DEFINE_RATELIMIT_STATE(ratelimit_uncorrected, 5*HZ, 2);
+        struct ratelimit_state *ratelimit;
 
-        if (__ratelimit(&ratelimit))
-                __ghes_print_estatus(pfx, ghes);
+        if (ghes_severity(estatus->error_severity) <= GHES_SEV_CORRECTED)
+                ratelimit = &ratelimit_corrected;
+        else
+                ratelimit = &ratelimit_uncorrected;
+        if (__ratelimit(ratelimit))
+                __ghes_print_estatus(pfx, generic, estatus);
 }
 
 static int ghes_proc(struct ghes *ghes)
@@ -393,8 +482,8 @@ static int ghes_proc(struct ghes *ghes)
         rc = ghes_read_estatus(ghes, 0);
         if (rc)
                 goto out;
-        ghes_print_estatus(NULL, ghes);
-        ghes_do_proc(ghes);
+        ghes_print_estatus(NULL, ghes->generic, ghes->estatus);
+        ghes_do_proc(ghes->estatus);
 
 out:
         ghes_clear_estatus(ghes);
@@ -453,6 +542,40 @@ static int ghes_notify_sci(struct notifier_block *this,
         return ret;
 }
 
+static void ghes_proc_in_irq(struct irq_work *irq_work)
+{
+        struct llist_node *llnode, *next, *tail = NULL;
+        struct ghes_estatus_node *estatus_node;
+        struct acpi_hest_generic_status *estatus;
+        u32 len, node_len;
+
+        /*
+         * Because the time order of estatus in list is reversed,
+         * revert it back to proper order.
+         */
+        llnode = llist_del_all(&ghes_estatus_llist);
+        while (llnode) {
+                next = llnode->next;
+                llnode->next = tail;
+                tail = llnode;
+                llnode = next;
+        }
+        llnode = tail;
+        while (llnode) {
+                next = llnode->next;
+                estatus_node = llist_entry(llnode, struct ghes_estatus_node,
+                                           llnode);
+                estatus = GHES_ESTATUS_FROM_NODE(estatus_node);
+                len = apei_estatus_len(estatus);
+                node_len = GHES_ESTATUS_NODE_LEN(len);
+                ghes_do_proc(estatus);
+                ghes_print_estatus(NULL, estatus_node->generic, estatus);
+                gen_pool_free(ghes_estatus_pool, (unsigned long)estatus_node,
+                              node_len);
+                llnode = next;
+        }
+}
+
 static int ghes_notify_nmi(struct notifier_block *this,
                                   unsigned long cmd, void *data)
 {
@@ -482,7 +605,8 @@ static int ghes_notify_nmi(struct notifier_block *this,
 
         if (sev_global >= GHES_SEV_PANIC) {
                 oops_begin();
-                __ghes_print_estatus(KERN_EMERG HW_ERR, ghes_global);
+                __ghes_print_estatus(KERN_EMERG HW_ERR, ghes_global->generic,
+                                     ghes_global->estatus);
                 /* reboot to log the error! */
                 if (panic_timeout == 0)
                         panic_timeout = ghes_panic_timeout;
@@ -490,12 +614,31 @@ static int ghes_notify_nmi(struct notifier_block *this,
         }
 
         list_for_each_entry_rcu(ghes, &ghes_nmi, list) {
+#ifdef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
+                u32 len, node_len;
+                struct ghes_estatus_node *estatus_node;
+                struct acpi_hest_generic_status *estatus;
+#endif
                 if (!(ghes->flags & GHES_TO_CLEAR))
                         continue;
-                /* Do not print estatus because printk is not NMI safe */
-                ghes_do_proc(ghes);
+#ifdef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
+                /* Save estatus for further processing in IRQ context */
+                len = apei_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) {
+                        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
                 ghes_clear_estatus(ghes);
         }
+#ifdef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
+        irq_work_queue(&ghes_proc_irq_work);
+#endif
 
 out:
         raw_spin_unlock(&ghes_nmi_lock);
@@ -510,10 +653,26 @@ static struct notifier_block ghes_notifier_nmi = {
         .notifier_call = ghes_notify_nmi,
 };
 
+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 int __devinit ghes_probe(struct platform_device *ghes_dev)
 {
         struct acpi_hest_generic *generic;
         struct ghes *ghes = NULL;
+        unsigned long len;
         int rc = -EINVAL;
 
         generic = *(struct acpi_hest_generic **)ghes_dev->dev.platform_data;
@@ -579,6 +738,8 @@ static int __devinit ghes_probe(struct platform_device *ghes_dev)
                 mutex_unlock(&ghes_list_mutex);
                 break;
         case ACPI_HEST_NOTIFY_NMI:
+                len = ghes_esource_prealloc_size(generic);
+                ghes_estatus_pool_expand(len);
                 mutex_lock(&ghes_list_mutex);
                 if (list_empty(&ghes_nmi))
                         register_die_notifier(&ghes_notifier_nmi);
@@ -603,6 +764,7 @@ static int __devexit ghes_remove(struct platform_device *ghes_dev)
 {
         struct ghes *ghes;
         struct acpi_hest_generic *generic;
+        unsigned long len;
 
         ghes = platform_get_drvdata(ghes_dev);
         generic = ghes->generic;
@@ -633,6 +795,8 @@ static int __devexit ghes_remove(struct platform_device *ghes_dev)
                  * freed after NMI handler finishes.
                  */
                 synchronize_rcu();
+                len = ghes_esource_prealloc_size(generic);
+                ghes_estatus_pool_shrink(len);
                 break;
         default:
                 BUG();
@@ -673,14 +837,20 @@ static int __init ghes_init(void)
                 return -EINVAL;
         }
 
+        init_irq_work(&ghes_proc_irq_work, ghes_proc_in_irq);
+
         rc = ghes_ioremap_init();
         if (rc)
                 goto err;
 
-        rc = platform_driver_register(&ghes_platform_driver);
+        rc = ghes_estatus_pool_init();
         if (rc)
                 goto err_ioremap_exit;
 
+        rc = platform_driver_register(&ghes_platform_driver);
+        if (rc)
+                goto err_pool_exit;
+
         rc = apei_osc_setup();
         if (rc == 0 && osc_sb_apei_support_acked)
                 pr_info(GHES_PFX "APEI firmware first mode is enabled by APEI bit and WHEA _OSC.\n");
@@ -692,6 +862,8 @@ static int __init ghes_init(void)
                 pr_info(GHES_PFX "Failed to enable APEI firmware first mode.\n");
 
         return 0;
+err_pool_exit:
+        ghes_estatus_pool_exit();
 err_ioremap_exit:
         ghes_ioremap_exit();
 err:
@@ -701,6 +873,7 @@ err:
 static void __exit ghes_exit(void)
 {
         platform_driver_unregister(&ghes_platform_driver);
+        ghes_estatus_pool_exit();
         ghes_ioremap_exit();
 }