[PATCH v6 4/5] dmaengine: idxd: Clean up descriptors with fault error

Dave Jiang
2020-09-24T18:01:28Z

Add code to "complete" a descriptor when the descriptor or its completion
address hit a fault error when SVA mode is being used. This error can be
triggered due to bad programming by the user. A lock is introduced in order
to protect the descriptor completion lists since the fault handler will run
from the system work queue after being scheduled in the interrupt handler.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
---
drivers/dma/idxd/idxd.h | 5 ++
drivers/dma/idxd/init.c | 1 +
drivers/dma/idxd/irq.c | 143 ++++++++++++++++++++++++++++++++++++----
3 files changed, 137 insertions(+), 12 deletions(-)

diff --git a/drivers/dma/idxd/idxd.h b/drivers/dma/idxd/idxd.h
index 43a216c42d25..b64b6266ca97 100644
--- a/drivers/dma/idxd/idxd.h
+++ b/drivers/dma/idxd/idxd.h
@@ -34,6 +34,11 @@ struct idxd_irq_entry {
int id;
struct llist_head pending_llist;
struct list_head work_list;
+ /*
+ * Lock to protect access between irq thread process descriptor
+ * and irq thread processing error descriptor.
+ */
+ spinlock_t list_lock;
};

struct idxd_group {
diff --git a/drivers/dma/idxd/init.c b/drivers/dma/idxd/init.c
index 626401a71fdd..1bb7637b02eb 100644
--- a/drivers/dma/idxd/init.c
+++ b/drivers/dma/idxd/init.c
@@ -97,6 +97,7 @@ static int idxd_setup_interrupts(struct idxd_device *idxd)
for (i = 0; i < msixcnt; i++) {
idxd->irq_entries[i].id = i;
idxd->irq_entries[i].idxd = idxd;
+ spin_lock_init(&idxd->irq_entries[i].list_lock);
}

msix = &idxd->msix_entries[0];
diff --git a/drivers/dma/idxd/irq.c b/drivers/dma/idxd/irq.c
index 17a65a13fb64..9e6cc55ad22f 100644
--- a/drivers/dma/idxd/irq.c
+++ b/drivers/dma/idxd/irq.c
@@ -11,6 +11,24 @@
#include "idxd.h"
#include "registers.h"

+enum irq_work_type {
+ IRQ_WORK_NORMAL = 0,
+ IRQ_WORK_PROCESS_FAULT,
+};
+
+struct idxd_fault {
+ struct work_struct work;
+ u64 addr;
+ struct idxd_device *idxd;
+};
+
+static int irq_process_work_list(struct idxd_irq_entry *irq_entry,
+ enum irq_work_type wtype,
+ int *processed, u64 data);
+static int irq_process_pending_llist(struct idxd_irq_entry *irq_entry,
+ enum irq_work_type wtype,
+ int *processed, u64 data);
+
static void idxd_device_reinit(struct work_struct *work)
{
struct idxd_device *idxd = container_of(work, struct idxd_device, work);
@@ -44,6 +62,46 @@ static void idxd_device_reinit(struct work_struct *work)
idxd_device_wqs_clear_state(idxd);
}

+static void idxd_device_fault_work(struct work_struct *work)
+{
+ struct idxd_fault *fault = container_of(work, struct idxd_fault, work);
+ struct idxd_irq_entry *ie;
+ int i;
+ int processed;
+ int irqcnt = fault->idxd->num_wq_irqs + 1;
+
+ for (i = 1; i < irqcnt; i++) {
+ ie = &fault->idxd->irq_entries[i];
+ irq_process_work_list(ie, IRQ_WORK_PROCESS_FAULT,
+ &processed, fault->addr);
+ if (processed)
+ break;
+
+ irq_process_pending_llist(ie, IRQ_WORK_PROCESS_FAULT,
+ &processed, fault->addr);
+ if (processed)
+ break;
+ }
+
+ kfree(fault);
+}
+
+static int idxd_device_schedule_fault_process(struct idxd_device *idxd,
+ u64 fault_addr)
+{
+ struct idxd_fault *fault;
+
+ fault = kmalloc(sizeof(*fault), GFP_ATOMIC);
+ if (!fault)
+ return -ENOMEM;
+
+ fault->addr = fault_addr;
+ fault->idxd = idxd;
+ INIT_WORK(&fault->work, idxd_device_fault_work);
+ queue_work(idxd->wq, &fault->work);
+ return 0;
+}
+
irqreturn_t idxd_irq_handler(int vec, void *data)
{
struct idxd_irq_entry *irq_entry = data;
@@ -125,6 +183,16 @@ irqreturn_t idxd_misc_thread(int vec, void *data)
if (!err)
goto out;

+ /*
+ * This case should rarely happen and typically is due to software
+ * programming error by the driver.
+ */
+ if (idxd->sw_err.valid &&
+ idxd->sw_err.desc_valid &&
+ idxd->sw_err.fault_addr)
+ idxd_device_schedule_fault_process(idxd,
+ idxd->sw_err.fault_addr);
+
gensts.bits = ioread32(idxd->reg_base + IDXD_GENSTATS_OFFSET);
if (gensts.state == IDXD_DEVICE_STATE_HALT) {
idxd->state = IDXD_DEV_HALTED;
@@ -152,57 +220,106 @@ irqreturn_t idxd_misc_thread(int vec, void *data)
return IRQ_HANDLED;
}

+static bool process_fault(struct idxd_desc *desc, u64 fault_addr)
+{
+ if ((u64)desc->hw == fault_addr ||
+ (u64)desc->completion == fault_addr) {
+ idxd_dma_complete_txd(desc, IDXD_COMPLETE_DEV_FAIL);
+ return true;
+ }
+
+ return false;
+}
+
+static bool complete_desc(struct idxd_desc *desc)
+{
+ if (desc->completion->status) {
+ idxd_dma_complete_txd(desc, IDXD_COMPLETE_NORMAL);
+ return true;
+ }
+
+ return false;
+}
+
static int irq_process_pending_llist(struct idxd_irq_entry *irq_entry,
- int *processed)
+ enum irq_work_type wtype,
+ int *processed, u64 data)
{
struct idxd_desc *desc, *t;
struct llist_node *head;
int queued = 0;
+ bool completed = false;
+ unsigned long flags;

*processed = 0;
head = llist_del_all(&irq_entry->pending_llist);
if (!head)
- return 0;
+ goto out;

llist_for_each_entry_safe(desc, t, head, llnode) {
- if (desc->completion->status) {
- idxd_dma_complete_txd(desc, IDXD_COMPLETE_NORMAL);
+ if (wtype == IRQ_WORK_NORMAL)
+ completed = complete_desc(desc);
+ else if (wtype == IRQ_WORK_PROCESS_FAULT)
+ completed = process_fault(desc, data);
+
+ if (completed) {
idxd_free_desc(desc->wq, desc);
(*processed)++;
+ if (wtype == IRQ_WORK_PROCESS_FAULT)
+ break;
} else {
- list_add_tail(&desc->list, &irq_entry->work_list);
+ spin_lock_irqsave(&irq_entry->list_lock, flags);
+ list_add_tail(&desc->list,
+ &irq_entry->work_list);
+ spin_unlock_irqrestore(&irq_entry->list_lock, flags);
queued++;
}
}

+ out:
return queued;
}

static int irq_process_work_list(struct idxd_irq_entry *irq_entry,
- int *processed)
+ enum irq_work_type wtype,
+ int *processed, u64 data)
{
struct list_head *node, *next;
int queued = 0;
+ bool completed = false;
+ unsigned long flags;

*processed = 0;
+ spin_lock_irqsave(&irq_entry->list_lock, flags);
if (list_empty(&irq_entry->work_list))
- return 0;
+ goto out;

list_for_each_safe(node, next, &irq_entry->work_list) {
struct idxd_desc *desc =
container_of(node, struct idxd_desc, list);

- if (desc->completion->status) {
+ spin_unlock_irqrestore(&irq_entry->list_lock, flags);
+ if (wtype == IRQ_WORK_NORMAL)
+ completed = complete_desc(desc);
+ else if (wtype == IRQ_WORK_PROCESS_FAULT)
+ completed = process_fault(desc, data);
+
+ if (completed) {
+ spin_lock_irqsave(&irq_entry->list_lock, flags);
list_del(&desc->list);
- /* process and callback */
- idxd_dma_complete_txd(desc, IDXD_COMPLETE_NORMAL);
+ spin_unlock_irqrestore(&irq_entry->list_lock, flags);
idxd_free_desc(desc->wq, desc);
(*processed)++;
+ if (wtype == IRQ_WORK_PROCESS_FAULT)
+ return queued;
} else {
queued++;
}
+ spin_lock_irqsave(&irq_entry->list_lock, flags);
}

+ out:
+ spin_unlock_irqrestore(&irq_entry->list_lock, flags);
return queued;
}

@@ -230,12 +347,14 @@ static int idxd_desc_process(struct idxd_irq_entry *irq_entry)
* 5. Repeat until no more descriptors.
*/
do {
- rc = irq_process_work_list(irq_entry, &processed);
+ rc = irq_process_work_list(irq_entry, IRQ_WORK_NORMAL,
+ &processed, 0);
total += processed;
if (rc != 0)
continue;

- rc = irq_process_pending_llist(irq_entry, &processed);
+ rc = irq_process_pending_llist(irq_entry, IRQ_WORK_NORMAL,
+ &processed, 0);
total += processed;
} while (rc != 0);

--
2.21.3