[PATCH v15 6/9] virtio-iommu: Implement fault reporting

[Eric Auger]

The event queue allows to report asynchronous errors.
The translate function now injects faults when relevant.

Signed-off-by: Eric Auger <address@hidden>
Reviewed-by: Peter Xu <address@hidden>

---
v13 -> v14:
- remove loop
- add Peter's R-b

v12 -> v13:
- return on virtio_error()

v11 -> v12:
- reporting the addr associated with the fault and set the
  VIRTIO_IOMMU_FAULT_F_ADDRESS flag.
- added cpu_to_le<n>

v10 -> v11:
- change a virtio_error into an error_report_once
  (no buffer available for output faults)
---
 hw/virtio/trace-events   |  1 +
 hw/virtio/virtio-iommu.c | 70 +++++++++++++++++++++++++++++++++++++---
 2 files changed, 66 insertions(+), 5 deletions(-)

diff --git a/hw/virtio/trace-events b/hw/virtio/trace-events
index 095aa8b509..e83500bee9 100644
--- a/hw/virtio/trace-events
+++ b/hw/virtio/trace-events
@@ -72,3 +72,4 @@ virtio_iommu_put_endpoint(uint32_t ep_id) "Free endpoint=%d"
 virtio_iommu_get_domain(uint32_t domain_id) "Alloc domain=%d"
 virtio_iommu_put_domain(uint32_t domain_id) "Free domain=%d"
 virtio_iommu_translate_out(uint64_t virt_addr, uint64_t phys_addr, uint32_t 
sid) "0x%"PRIx64" -> 0x%"PRIx64 " for sid=%d"
+virtio_iommu_report_fault(uint8_t reason, uint32_t flags, uint32_t endpoint, 
uint64_t addr) "FAULT reason=%d flags=%d endpoint=%d address =0x%"PRIx64
diff --git a/hw/virtio/virtio-iommu.c b/hw/virtio/virtio-iommu.c
index 59e9cd3d9a..8509f64004 100644
--- a/hw/virtio/virtio-iommu.c
+++ b/hw/virtio/virtio-iommu.c
@@ -468,6 +468,48 @@ out:
     }
 }
 
+static void virtio_iommu_report_fault(VirtIOIOMMU *viommu, uint8_t reason,
+                                      int flags, uint32_t endpoint,
+                                      uint64_t address)
+{
+    VirtIODevice *vdev = &viommu->parent_obj;
+    VirtQueue *vq = viommu->event_vq;
+    struct virtio_iommu_fault fault;
+    VirtQueueElement *elem;
+    size_t sz;
+
+    memset(&fault, 0, sizeof(fault));
+    fault.reason = reason;
+    fault.flags = cpu_to_le32(flags);
+    fault.endpoint = cpu_to_le32(endpoint);
+    fault.address = cpu_to_le64(address);
+
+    elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
+
+    if (!elem) {
+        error_report_once(
+            "no buffer available in event queue to report event");
+        return;
+    }
+
+    if (iov_size(elem->in_sg, elem->in_num) < sizeof(fault)) {
+        virtio_error(vdev, "error buffer of wrong size");
+        virtqueue_detach_element(vq, elem, 0);
+        g_free(elem);
+        return;
+    }
+
+    sz = iov_from_buf(elem->in_sg, elem->in_num, 0,
+                      &fault, sizeof(fault));
+    assert(sz == sizeof(fault));
+
+    trace_virtio_iommu_report_fault(reason, flags, endpoint, address);
+    virtqueue_push(vq, elem, sz);
+    virtio_notify(vdev, vq);
+    g_free(elem);
+
+}
+
 static IOMMUTLBEntry virtio_iommu_translate(IOMMUMemoryRegion *mr, hwaddr addr,
                                             IOMMUAccessFlags flag,
                                             int iommu_idx)
@@ -476,9 +518,10 @@ static IOMMUTLBEntry 
virtio_iommu_translate(IOMMUMemoryRegion *mr, hwaddr addr,
     VirtIOIOMMUInterval interval, *mapping_key;
     VirtIOIOMMUMapping *mapping_value;
     VirtIOIOMMU *s = sdev->viommu;
+    bool read_fault, write_fault;
     VirtIOIOMMUEndpoint *ep;
+    uint32_t sid, flags;
     bool bypass_allowed;
-    uint32_t sid;
     bool found;
 
     interval.low = addr;
@@ -504,6 +547,9 @@ static IOMMUTLBEntry 
virtio_iommu_translate(IOMMUMemoryRegion *mr, hwaddr addr,
     if (!ep) {
         if (!bypass_allowed) {
             error_report_once("%s sid=%d is not known!!", __func__, sid);
+            virtio_iommu_report_fault(s, VIRTIO_IOMMU_FAULT_R_UNKNOWN,
+                                      VIRTIO_IOMMU_FAULT_F_ADDRESS,
+                                      sid, addr);
         } else {
             entry.perm = flag;
         }
@@ -515,6 +561,9 @@ static IOMMUTLBEntry 
virtio_iommu_translate(IOMMUMemoryRegion *mr, hwaddr addr,
             error_report_once("%s %02x:%02x.%01x not attached to any domain",
                               __func__, PCI_BUS_NUM(sid),
                               PCI_SLOT(sid), PCI_FUNC(sid));
+            virtio_iommu_report_fault(s, VIRTIO_IOMMU_FAULT_R_DOMAIN,
+                                      VIRTIO_IOMMU_FAULT_F_ADDRESS,
+                                      sid, addr);
         } else {
             entry.perm = flag;
         }
@@ -527,15 +576,26 @@ static IOMMUTLBEntry 
virtio_iommu_translate(IOMMUMemoryRegion *mr, hwaddr addr,
     if (!found) {
         error_report_once("%s no mapping for 0x%"PRIx64" for sid=%d",
                           __func__, addr, sid);
+        virtio_iommu_report_fault(s, VIRTIO_IOMMU_FAULT_R_MAPPING,
+                                  VIRTIO_IOMMU_FAULT_F_ADDRESS,
+                                  sid, addr);
         goto unlock;
     }
 
-    if (((flag & IOMMU_RO) &&
-            !(mapping_value->flags & VIRTIO_IOMMU_MAP_F_READ)) ||
-        ((flag & IOMMU_WO) &&
-            !(mapping_value->flags & VIRTIO_IOMMU_MAP_F_WRITE))) {
+    read_fault = (flag & IOMMU_RO) &&
+                    !(mapping_value->flags & VIRTIO_IOMMU_MAP_F_READ);
+    write_fault = (flag & IOMMU_WO) &&
+                    !(mapping_value->flags & VIRTIO_IOMMU_MAP_F_WRITE);
+
+    flags = read_fault ? VIRTIO_IOMMU_FAULT_F_READ : 0;
+    flags |= write_fault ? VIRTIO_IOMMU_FAULT_F_WRITE : 0;
+    if (flags) {
         error_report_once("%s permission error on 0x%"PRIx64"(%d): allowed=%d",
                           __func__, addr, flag, mapping_value->flags);
+        flags |= VIRTIO_IOMMU_FAULT_F_ADDRESS;
+        virtio_iommu_report_fault(s, VIRTIO_IOMMU_FAULT_R_MAPPING,
+                                  flags | VIRTIO_IOMMU_FAULT_F_ADDRESS,
+                                  sid, addr);
         goto unlock;
     }
     entry.translated_addr = addr - mapping_key->low + mapping_value->phys_addr;
-- 
2.20.1