[PATCH 1/2] iommu/dmar: collect fault statistics

From: Yuri Volchkov
Date: Tue Oct 15 2019 - 11:12:04 EST

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Currently dmar_fault handler only prints a message in the dmesg. This
commit introduces counters - how many faults have happened, and
exposes them via sysfs. Each pci device will have an entry
'dmar_faults' reading from which will give user 3 lines
remap: xxx
read: xxx
write: xxx

This functionality is targeted for health monitoring daemons.

Signed-off-by: Yuri Volchkov <volchkov@xxxxxxxxx>
---
drivers/iommu/dmar.c | 133 +++++++++++++++++++++++++++++++-----
drivers/pci/pci-sysfs.c | 20 ++++++
include/linux/intel-iommu.h | 3 +
include/linux/pci.h | 11 +++
4 files changed, 150 insertions(+), 17 deletions(-)

diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
index eecd6a421667..0749873e3e41 100644
--- a/drivers/iommu/dmar.c
+++ b/drivers/iommu/dmar.c
@@ -1107,6 +1107,7 @@ static void free_iommu(struct intel_iommu *iommu)
}

if (iommu->irq) {
+ destroy_workqueue(iommu->fault_wq);
if (iommu->pr_irq) {
free_irq(iommu->pr_irq, iommu);
dmar_free_hwirq(iommu->pr_irq);
@@ -1672,9 +1673,46 @@ void dmar_msi_read(int irq, struct msi_msg *msg)
raw_spin_unlock_irqrestore(&iommu->register_lock, flag);
}

-static int dmar_fault_do_one(struct intel_iommu *iommu, int type,
- u8 fault_reason, int pasid, u16 source_id,
- unsigned long long addr)
+struct dmar_fault_info {
+ struct work_struct work;
+ struct intel_iommu *iommu;
+ int type;
+ int pasid;
+ u16 source_id;
+ unsigned long long addr;
+ u8 fault_reason;
+};
+
+static struct kmem_cache *dmar_fault_info_cache;
+int __init dmar_fault_info_cache_init(void)
+{
+ int ret = 0;
+
+ dmar_fault_info_cache =
+ kmem_cache_create("dmar_fault_info",
+ sizeof(struct dmar_fault_info), 0,
+ SLAB_HWCACHE_ALIGN, NULL);
+ if (!dmar_fault_info_cache) {
+ pr_err("Couldn't create dmar_fault_info cache\n");
+ ret = -ENOMEM;
+ }
+
+ return ret;
+}
+
+static inline void *alloc_dmar_fault_info(void)
+{
+ return kmem_cache_alloc(dmar_fault_info_cache, GFP_ATOMIC);
+}
+
+static inline void free_dmar_fault_info(void *vaddr)
+{
+ kmem_cache_free(dmar_fault_info_cache, vaddr);
+}
+
+static int dmar_fault_dump_one(struct intel_iommu *iommu, int type,
+ u8 fault_reason, int pasid, u16 source_id,
+ unsigned long long addr)
{
const char *reason;
int fault_type;
@@ -1695,6 +1733,57 @@ static int dmar_fault_do_one(struct intel_iommu *iommu, int type,
return 0;
}

+static int dmar_fault_handle_one(struct dmar_fault_info *info)
+{
+ struct pci_dev *pdev;
+ u8 devfn;
+ atomic_t *pcnt;
+
+ devfn = PCI_DEVFN(PCI_SLOT(info->source_id), PCI_FUNC(info->source_id));
+ pdev = pci_get_domain_bus_and_slot(info->iommu->segment,
+ PCI_BUS_NUM(info->source_id), devfn);
+
+ if (!pdev)
+ return -ENXIO;
+
+ if (info->fault_reason == INTR_REMAP)
+ pcnt = &pdev->faults_cnt.remap;
+ else if (info->type)
+ pcnt = &pdev->faults_cnt.read;
+ else
+ pcnt = &pdev->faults_cnt.write;
+
+ atomic_inc(pcnt);
+ return 0;
+}
+
+static void dmar_fault_handle_work(struct work_struct *work)
+{
+ struct dmar_fault_info *info;
+
+ info = container_of(work, struct dmar_fault_info, work);
+
+ dmar_fault_handle_one(info);
+ free_dmar_fault_info(info);
+}
+
+static int dmar_fault_schedule_one(struct intel_iommu *iommu, int type,
+ u8 fault_reason, int pasid, u16 source_id,
+ unsigned long long addr)
+{
+ struct dmar_fault_info *info = alloc_dmar_fault_info();
+
+ INIT_WORK(&info->work, dmar_fault_handle_work);
+ info->iommu = iommu;
+ info->type = type;
+ info->fault_reason = fault_reason;
+ info->pasid = pasid;
+ info->source_id = source_id;
+ info->addr = addr;
+
+ return queue_work(iommu->fault_wq, &info->work);
+}
+
#define PRIMARY_FAULT_REG_LEN (16)
irqreturn_t dmar_fault(int irq, void *dev_id)
{
@@ -1733,20 +1822,18 @@ irqreturn_t dmar_fault(int irq, void *dev_id)
if (!(data & DMA_FRCD_F))
break;

- if (!ratelimited) {
- fault_reason = dma_frcd_fault_reason(data);
- type = dma_frcd_type(data);
+ fault_reason = dma_frcd_fault_reason(data);
+ type = dma_frcd_type(data);

- pasid = dma_frcd_pasid_value(data);
- data = readl(iommu->reg + reg +
- fault_index * PRIMARY_FAULT_REG_LEN + 8);
- source_id = dma_frcd_source_id(data);
+ pasid = dma_frcd_pasid_value(data);
+ data = readl(iommu->reg + reg +
+ fault_index * PRIMARY_FAULT_REG_LEN + 8);
+ source_id = dma_frcd_source_id(data);

- pasid_present = dma_frcd_pasid_present(data);
- guest_addr = dmar_readq(iommu->reg + reg +
+ pasid_present = dma_frcd_pasid_present(data);
+ guest_addr = dmar_readq(iommu->reg + reg +
fault_index * PRIMARY_FAULT_REG_LEN);
- guest_addr = dma_frcd_page_addr(guest_addr);
- }
+ guest_addr = dma_frcd_page_addr(guest_addr);

/* clear the fault */
writel(DMA_FRCD_F, iommu->reg + reg +
@@ -1756,9 +1843,13 @@ irqreturn_t dmar_fault(int irq, void *dev_id)

if (!ratelimited)
/* Using pasid -1 if pasid is not present */
- dmar_fault_do_one(iommu, type, fault_reason,
- pasid_present ? pasid : -1,
- source_id, guest_addr);
+ dmar_fault_dump_one(iommu, type, fault_reason,
+ pasid_present ? pasid : -1,
+ source_id, guest_addr);
+ if (irq != -1)
+ dmar_fault_schedule_one(iommu, type, fault_reason,
+ pasid_present ? pasid : -1,
+ source_id, guest_addr);

fault_index++;
if (fault_index >= cap_num_fault_regs(iommu->cap))
@@ -1784,6 +1875,10 @@ int dmar_set_interrupt(struct intel_iommu *iommu)
if (iommu->irq)
return 0;

+ iommu->fault_wq = alloc_ordered_workqueue("fault_%s", 0, iommu->name);
+ if (!iommu->fault_wq)
+ return -ENOMEM;
+
irq = dmar_alloc_hwirq(iommu->seq_id, iommu->node, iommu);
if (irq > 0) {
iommu->irq = irq;
@@ -1803,6 +1898,9 @@ int __init enable_drhd_fault_handling(void)
struct dmar_drhd_unit *drhd;
struct intel_iommu *iommu;

+ if (dmar_fault_info_cache_init())
+ return -1;
+
/*
* Enable fault control interrupt.
*/
@@ -1813,6 +1911,7 @@ int __init enable_drhd_fault_handling(void)
if (ret) {
pr_err("DRHD %Lx: failed to enable fault, interrupt, ret %d\n",
(unsigned long long)drhd->reg_base_addr, ret);
+ kmem_cache_destroy(dmar_fault_info_cache);
return -1;
}

diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index 07bd84c50238..d01514fca6d1 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -263,6 +263,23 @@ static ssize_t ari_enabled_show(struct device *dev,
}
static DEVICE_ATTR_RO(ari_enabled);

+#ifdef CONFIG_DMAR_TABLE
+static ssize_t dmar_faults_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct pci_dev *pdev = to_pci_dev(dev);
+ int remap, read, write;
+
+ remap = atomic_xchg(&pdev->faults_cnt.remap, 0);
+ read = atomic_xchg(&pdev->faults_cnt.read, 0);
+ write = atomic_xchg(&pdev->faults_cnt.write, 0);
+
+ return sprintf(buf, "remap: %d\nread: %d\nwrite: %d\n", remap, read,
+ write);
+}
+static DEVICE_ATTR_RO(dmar_faults);
+#endif
+
static ssize_t modalias_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
@@ -623,6 +640,9 @@ static struct attribute *pci_dev_attrs[] = {
#endif
&dev_attr_driver_override.attr,
&dev_attr_ari_enabled.attr,
+#ifdef CONFIG_DMAR_TABLE
+ &dev_attr_dmar_faults.attr,
+#endif
NULL,
};

diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
index ed11ef594378..f8963c833fb0 100644
--- a/include/linux/intel-iommu.h
+++ b/include/linux/intel-iommu.h
@@ -552,6 +552,9 @@ struct intel_iommu {
struct iommu_device iommu; /* IOMMU core code handle */
int node;
u32 flags; /* Software defined flags */
+#ifdef CONFIG_DMAR_TABLE
+ struct workqueue_struct *fault_wq; /* Fault handler */
+#endif
};

/* PCI domain-device relationship */
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 14efa2586a8c..d9cc94fbf0ee 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -286,6 +286,14 @@ struct pci_vpd;
struct pci_sriov;
struct pci_p2pdma;

+#ifdef CONFIG_DMAR_TABLE
+struct pci_dmar_faults_cnt {
+ atomic_t read; /* How many read faults occurred */
+ atomic_t write; /* How many write faults occurred */
+ atomic_t remap; /* How many remap faults occurred */
+};
+#endif
+
/* The pci_dev structure describes PCI devices */
struct pci_dev {
struct list_head bus_list; /* Node in per-bus list */
@@ -468,6 +476,9 @@ struct pci_dev {
char *driver_override; /* Driver name to force a match */

unsigned long priv_flags; /* Private flags for the PCI driver */
+#ifdef CONFIG_DMAR_TABLE
+ struct pci_dmar_faults_cnt faults_cnt; /* Dmar fault statistics */
+#endif
};

static inline struct pci_dev *pci_physfn(struct pci_dev *dev)
--
2.23.0

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