[PATCH for-5.0 v11 09/20] virtio-iommu: Implement fault reporting

[Eric Auger <eric.auger@redhat.com>]

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

Signed-off-by: Eric Auger <eric.auger@redhat.com>

---

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 | 69 +++++++++++++++++++++++++++++++++++++---
 2 files changed, 65 insertions(+), 5 deletions(-)

diff --git a/hw/virtio/trace-events b/hw/virtio/trace-events
index de7cbb3c8f..a572eb71aa 100644
--- a/hw/virtio/trace-events
+++ b/hw/virtio/trace-events
@@ -73,3 +73,4 @@ 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 a83666557b..723616a5db 100644
--- a/hw/virtio/virtio-iommu.c
+++ b/hw/virtio/virtio-iommu.c
@@ -407,6 +407,51 @@ out:
     }
 }
 
+static void virtio_iommu_report_fault(VirtIOIOMMU *viommu, uint8_t reason,
+                                      uint32_t 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 = flags;
+    fault.endpoint = endpoint;
+    fault.address = address;
+
+    for (;;) {
+        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);
+            continue;
+        }
+        break;
+    }
+    /* we have a buffer to fill in */
+    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)
@@ -415,9 +460,10 @@ static IOMMUTLBEntry virtio_iommu_translate(IOMMUMemoryRegion *mr, hwaddr addr,
     viommu_interval interval, *mapping_key;
     viommu_mapping *mapping_value;
     VirtIOIOMMU *s = sdev->viommu;
+    bool read_fault, write_fault;
     viommu_endpoint *ep;
+    uint32_t sid, flags;
     bool bypass_allowed;
-    uint32_t sid;
     bool found;
 
     interval.low = addr;
@@ -443,6 +489,8 @@ 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,
+                                      0, sid, 0);
         } else {
             entry.perm = flag;
         }
@@ -455,6 +503,8 @@ static IOMMUTLBEntry virtio_iommu_translate(IOMMUMemoryRegion *mr, hwaddr addr,
                           "%s %02x:%02x.%01x not attached to any domain\n",
                           __func__, PCI_BUS_NUM(sid),
                           PCI_SLOT(sid), PCI_FUNC(sid));
+            virtio_iommu_report_fault(s, VIRTIO_IOMMU_FAULT_R_DOMAIN,
+                                      0, sid, 0);
         } else {
             entry.perm = flag;
         }
@@ -468,16 +518,25 @@ static IOMMUTLBEntry virtio_iommu_translate(IOMMUMemoryRegion *mr, hwaddr addr,
         qemu_log_mask(LOG_GUEST_ERROR,
                       "%s no mapping for 0x%"PRIx64" for sid=%d\n",
                       __func__, addr, sid);
+        virtio_iommu_report_fault(s, VIRTIO_IOMMU_FAULT_R_MAPPING,
+                                  0, 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) {
         qemu_log_mask(LOG_GUEST_ERROR,
                       "Permission error on 0x%"PRIx64"(%d): allowed=%d\n",
                       addr, flag, mapping_value->flags);
+        flags |= VIRTIO_IOMMU_FAULT_F_ADDRESS;
+        virtio_iommu_report_fault(s, VIRTIO_IOMMU_FAULT_R_MAPPING,
+                                  flags, sid, addr);
         goto unlock;
     }
     entry.translated_addr = addr - mapping_key->low + mapping_value->phys_addr;
-- 
2.20.1