iommu/amd: Implement notifier for PPR faults

Add a notifer at which a module can attach to get informed
about incoming PPR faults.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>

1 files changed, 89 insertions, 1 deletions

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 7ccfc80ceb7a..db9b788c28ba 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -17,6 +17,7 @@
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  */
 
+#include <linux/ratelimit.h>
 #include <linux/pci.h>
 #include <linux/pci-ats.h>
 #include <linux/bitmap.h>
@@ -28,6 +29,8 @@
 #include <linux/iommu.h>
 #include <linux/delay.h>
 #include <linux/amd-iommu.h>
+#include <linux/notifier.h>
+#include <linux/export.h>
 #include <asm/msidef.h>
 #include <asm/proto.h>
 #include <asm/iommu.h>
@@ -59,6 +62,8 @@ static struct protection_domain *pt_domain;
 
 static struct iommu_ops amd_iommu_ops;
 
+static ATOMIC_NOTIFIER_HEAD(ppr_notifier);
+
 /*
  * general struct to manage commands send to an IOMMU
  */
@@ -488,12 +493,82 @@ static void iommu_poll_events(struct amd_iommu *iommu)
         spin_unlock_irqrestore(&iommu->lock, flags);
 }
 
+static void iommu_handle_ppr_entry(struct amd_iommu *iommu, u32 head)
+{
+        struct amd_iommu_fault fault;
+        volatile u64 *raw;
+        int i;
+
+        raw = (u64 *)(iommu->ppr_log + head);
+
+        /*
+         * Hardware bug: Interrupt may arrive before the entry is written to
+         * memory. If this happens we need to wait for the entry to arrive.
+         */
+        for (i = 0; i < LOOP_TIMEOUT; ++i) {
+                if (PPR_REQ_TYPE(raw[0]) != 0)
+                        break;
+                udelay(1);
+        }
+
+        if (PPR_REQ_TYPE(raw[0]) != PPR_REQ_FAULT) {
+                pr_err_ratelimited("AMD-Vi: Unknown PPR request received\n");
+                return;
+        }
+
+        fault.address   = raw[1];
+        fault.pasid     = PPR_PASID(raw[0]);
+        fault.device_id = PPR_DEVID(raw[0]);
+        fault.tag       = PPR_TAG(raw[0]);
+        fault.flags     = PPR_FLAGS(raw[0]);
+
+        /*
+         * To detect the hardware bug we need to clear the entry
+         * to back to zero.
+         */
+        raw[0] = raw[1] = 0;
+
+        atomic_notifier_call_chain(&ppr_notifier, 0, &fault);
+}
+
+static void iommu_poll_ppr_log(struct amd_iommu *iommu)
+{
+        unsigned long flags;
+        u32 head, tail;
+
+        if (iommu->ppr_log == NULL)
+                return;
+
+        spin_lock_irqsave(&iommu->lock, flags);
+
+        head = readl(iommu->mmio_base + MMIO_PPR_HEAD_OFFSET);
+        tail = readl(iommu->mmio_base + MMIO_PPR_TAIL_OFFSET);
+
+        while (head != tail) {
+
+                /* Handle PPR entry */
+                iommu_handle_ppr_entry(iommu, head);
+
+                /* Update and refresh ring-buffer state*/
+                head = (head + PPR_ENTRY_SIZE) % PPR_LOG_SIZE;
+                writel(head, iommu->mmio_base + MMIO_PPR_HEAD_OFFSET);
+                tail = readl(iommu->mmio_base + MMIO_PPR_TAIL_OFFSET);
+        }
+
+        /* enable ppr interrupts again */
+        writel(MMIO_STATUS_PPR_INT_MASK, iommu->mmio_base + MMIO_STATUS_OFFSET);
+
+        spin_unlock_irqrestore(&iommu->lock, flags);
+}
+
 irqreturn_t amd_iommu_int_thread(int irq, void *data)
 {
         struct amd_iommu *iommu;
 
-        for_each_iommu(iommu)
+        for_each_iommu(iommu) {
                 iommu_poll_events(iommu);
+                iommu_poll_ppr_log(iommu);
+        }
 
         return IRQ_HANDLED;
 }
@@ -2888,3 +2963,16 @@ int __init amd_iommu_init_passthrough(void)
 
         return 0;
 }
+
+/* IOMMUv2 specific functions */
+int amd_iommu_register_ppr_notifier(struct notifier_block *nb)
+{
+        return atomic_notifier_chain_register(&ppr_notifier, nb);
+}
+EXPORT_SYMBOL(amd_iommu_register_ppr_notifier);
+
+int amd_iommu_unregister_ppr_notifier(struct notifier_block *nb)
+{
+        return atomic_notifier_chain_unregister(&ppr_notifier, nb);
+}
+EXPORT_SYMBOL(amd_iommu_unregister_ppr_notifier);