[PATCH v2 1/2] powerpc/mce: Add MCE notification chain

---
  arch/powerpc/platforms/pseries/papr_scm.c | 96 ++++++++++++++++++++++-
  1 file changed, 95 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/platforms/pseries/papr_scm.c b/arch/powerpc/platforms/pseries/papr_scm.c
index 9c569078a09fd..90729029ca010 100644
--- a/arch/powerpc/platforms/pseries/papr_scm.c
+++ b/arch/powerpc/platforms/pseries/papr_scm.c

@@ -13,9 +13,11 @@
  #include <linux/platform_device.h>
  #include <linux/delay.h>
  #include <linux/seq_buf.h>
+#include <linux/nd.h>
  
  #include <asm/plpar_wrappers.h>
  #include <asm/papr_pdsm.h>
+#include <asm/mce.h>
  
  #define BIND_ANY_ADDR (~0ul)
  

@@ -80,6 +82,7 @@ struct papr_scm_priv {
  	struct resource res;
  	struct nd_region *region;
  	struct nd_interleave_set nd_set;
+	struct list_head region_list;
  
  	/* Protect dimm health data from concurrent read/writes */
  	struct mutex health_mutex;

@@ -91,6 +94,9 @@ struct papr_scm_priv {
  	u64 health_bitmap;
  };
  
+LIST_HEAD(papr_nd_regions);
+DEFINE_MUTEX(papr_ndr_lock);
+
  static int drc_pmem_bind(struct papr_scm_priv *p)
  {
  	unsigned long ret[PLPAR_HCALL_BUFSIZE];

@@ -759,6 +765,10 @@ static int papr_scm_nvdimm_init(struct papr_scm_priv *p)
  		dev_info(dev, "Region registered with target node %d and online node %d",
  			 target_nid, online_nid);
  
+	mutex_lock(&papr_ndr_lock);
+	list_add_tail(&p->region_list, &papr_nd_regions);
+	mutex_unlock(&papr_ndr_lock);
+
  	return 0;
  
  err:	nvdimm_bus_unregister(p->bus);

@@ -766,6 +776,68 @@ err:	nvdimm_bus_unregister(p->bus);
  	return -ENXIO;
  }
  
+static void papr_scm_add_badblock(struct nd_region *region,
+				  struct nvdimm_bus *bus, u64 phys_addr)
+{
+	u64 aligned_addr = ALIGN_DOWN(phys_addr, L1_CACHE_BYTES);
+
+	if (nvdimm_bus_add_badrange(bus, aligned_addr, L1_CACHE_BYTES)) {
+		pr_err("Bad block registration for 0x%llx failed\n", phys_addr);
+		return;
+	}
+
+	pr_debug("Add memory range (0x%llx - 0x%llx) as bad range\n",
+		 aligned_addr, aligned_addr + L1_CACHE_BYTES);
+
+	nvdimm_region_notify(region, NVDIMM_REVALIDATE_POISON);
+}
+
+static int handle_mce_ue(struct notifier_block *nb, unsigned long val,
+			 void *data)
+{
+	struct machine_check_event *evt = data;
+	struct papr_scm_priv *p;
+	u64 phys_addr;
+	bool found = false;
+
+	if (evt->error_type != MCE_ERROR_TYPE_UE)
+		return NOTIFY_DONE;
+
+	if (list_empty(&papr_nd_regions))
+		return NOTIFY_DONE;
+
+	/*
+	 * The physical address obtained here is PAGE_SIZE aligned, so get the
+	 * exact address from the effective address
+	 */
+	phys_addr = evt->u.ue_error.physical_address +
+			(evt->u.ue_error.effective_address & ~PAGE_MASK);
+
+	if (!evt->u.ue_error.physical_address_provided ||
+	    !is_zone_device_page(pfn_to_page(phys_addr >> PAGE_SHIFT)))
+		return NOTIFY_DONE;
+
+	/* mce notifier is called from a process context, so mutex is safe */
+	mutex_lock(&papr_ndr_lock);
+	list_for_each_entry(p, &papr_nd_regions, region_list) {
+		if (phys_addr >= p->res.start && phys_addr <= p->res.end) {
+			found = true;
+			break;
+		}
+	}
+
+	if (found)
+		papr_scm_add_badblock(p->region, p->bus, phys_addr);
+
+	mutex_unlock(&papr_ndr_lock);
+
+	return found ? NOTIFY_OK : NOTIFY_DONE;
+}
+
+static struct notifier_block mce_ue_nb = {
+	.notifier_call = handle_mce_ue
+};
+
  static int papr_scm_probe(struct platform_device *pdev)
  {
  	struct device_node *dn = pdev->dev.of_node;

@@ -866,6 +938,10 @@ static int papr_scm_remove(struct platform_device *pdev)
  {
  	struct papr_scm_priv *p = platform_get_drvdata(pdev);
  
+	mutex_lock(&papr_ndr_lock);
+	list_del(&p->region_list);
+	mutex_unlock(&papr_ndr_lock);
+
  	nvdimm_bus_unregister(p->bus);
  	drc_pmem_unbind(p);
  	kfree(p->bus_desc.provider_name);

@@ -888,7 +964,25 @@ static struct platform_driver papr_scm_driver = {
  	},
  };
  
-module_platform_driver(papr_scm_driver);
+static int __init papr_scm_init(void)
+{
+	int ret;
+
+	ret = platform_driver_register(&papr_scm_driver);
+	if (!ret)
+		mce_register_notifier(&mce_ue_nb);
+
+	return ret;
+}
+module_init(papr_scm_init);
+
+static void __exit papr_scm_exit(void)
+{
+	mce_unregister_notifier(&mce_ue_nb);
+	platform_driver_unregister(&papr_scm_driver);
+}
+module_exit(papr_scm_exit);
+
  MODULE_DEVICE_TABLE(of, papr_scm_match);
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("IBM Corporation");

---
  arch/powerpc/include/asm/mce.h |  2 ++
  arch/powerpc/kernel/mce.c      | 15 +++++++++++++++
  2 files changed, 17 insertions(+)

v2: Address comments from Christophe.

RESEND: Sending the two patches together so the dependencies are clear. The
earlier patch reviews are here [1]; rebase the patches on top on 5.8-rc4

[1]: https://lore.kernel.org/linuxppc-dev/20200330071219.12284-1-ganeshgr@linux.ibm.com/

diff --git a/arch/powerpc/include/asm/mce.h b/arch/powerpc/include/asm/mce.h
index 376a395daf329..7bdd0cd4f2de0 100644
--- a/arch/powerpc/include/asm/mce.h
+++ b/arch/powerpc/include/asm/mce.h

@@ -220,6 +220,8 @@ extern void machine_check_print_event_info(struct machine_check_event *evt,
  unsigned long addr_to_pfn(struct pt_regs *regs, unsigned long addr);
  extern void mce_common_process_ue(struct pt_regs *regs,
  				  struct mce_error_info *mce_err);
+int mce_register_notifier(struct notifier_block *nb);
+int mce_unregister_notifier(struct notifier_block *nb);
  #ifdef CONFIG_PPC_BOOK3S_64
  void flush_and_reload_slb(void);
  #endif /* CONFIG_PPC_BOOK3S_64 */

diff --git a/arch/powerpc/kernel/mce.c b/arch/powerpc/kernel/mce.c
index fd90c0eda2290..b7b3ed4e61937 100644
--- a/arch/powerpc/kernel/mce.c
+++ b/arch/powerpc/kernel/mce.c

@@ -49,6 +49,20 @@ static struct irq_work mce_ue_event_irq_work = {
  
  DECLARE_WORK(mce_ue_event_work, machine_process_ue_event);
  
+static BLOCKING_NOTIFIER_HEAD(mce_notifier_list);
+
+int mce_register_notifier(struct notifier_block *nb)
+{
+	return blocking_notifier_chain_register(&mce_notifier_list, nb);
+}
+EXPORT_SYMBOL_GPL(mce_register_notifier);
+
+int mce_unregister_notifier(struct notifier_block *nb)
+{
+	return blocking_notifier_chain_unregister(&mce_notifier_list, nb);
+}
+EXPORT_SYMBOL_GPL(mce_unregister_notifier);
+
  static void mce_set_error_info(struct machine_check_event *mce,
  			       struct mce_error_info *mce_err)
  {

@@ -278,6 +292,7 @@ static void machine_process_ue_event(struct work_struct *work)
  	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]);
+		blocking_notifier_call_chain(&mce_notifier_list, 0, evt);
  #ifdef CONFIG_MEMORY_FAILURE
  		/*
  		 * This should probably queued elsewhere, but