iommu/virtio: Add event queue

The event queue offers a way for the device to report access faults from
endpoints. It is implemented on virtqueue #1. Whenever the host needs to
signal a fault, it fills one of the buffers offered by the guest and
interrupts it.

Tested-by: Bharat Bhushan <bharat.bhushan@nxp.com>
Tested-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/drivers/iommu/virtio-iommu.c b/drivers/iommu/virtio-iommu.c
index 5e194493a531a5bdc79030290fc7463f13f58ed9..4620dd221ffd3db22ef223b311f6d20de4c8de4b 100644 (file)
--- a/drivers/iommu/virtio-iommu.c
+++ b/drivers/iommu/virtio-iommu.c
@@ -29,7 +29,8 @@
 #define MSI_IOVA_LENGTH                        0x100000
 
 #define VIOMMU_REQUEST_VQ              0
-#define VIOMMU_NR_VQS                  1
+#define VIOMMU_EVENT_VQ                        1
+#define VIOMMU_NR_VQS                  2
 
 struct viommu_dev {
        struct iommu_device             iommu;
@@ -41,6 +42,7 @@ struct viommu_dev {
        struct virtqueue                *vqs[VIOMMU_NR_VQS];
        spinlock_t                      request_lock;
        struct list_head                requests;
+       void                            *evts;
 
        /* Device configuration */
        struct iommu_domain_geometry    geometry;
@@ -82,6 +84,15 @@ struct viommu_request {
        char                            buf[];
 };
 
+#define VIOMMU_FAULT_RESV_MASK         0xffffff00
+
+struct viommu_event {
+       union {
+               u32                     head;
+               struct virtio_iommu_fault fault;
+       };
+};
+
 #define to_viommu_domain(domain)       \
        container_of(domain, struct viommu_domain, domain)
 
@@ -503,6 +514,68 @@ out_free:
        return ret;
 }
 
+static int viommu_fault_handler(struct viommu_dev *viommu,
+                               struct virtio_iommu_fault *fault)
+{
+       char *reason_str;
+
+       u8 reason       = fault->reason;
+       u32 flags       = le32_to_cpu(fault->flags);
+       u32 endpoint    = le32_to_cpu(fault->endpoint);
+       u64 address     = le64_to_cpu(fault->address);
+
+       switch (reason) {
+       case VIRTIO_IOMMU_FAULT_R_DOMAIN:
+               reason_str = "domain";
+               break;
+       case VIRTIO_IOMMU_FAULT_R_MAPPING:
+               reason_str = "page";
+               break;
+       case VIRTIO_IOMMU_FAULT_R_UNKNOWN:
+       default:
+               reason_str = "unknown";
+               break;
+       }
+
+       /* TODO: find EP by ID and report_iommu_fault */
+       if (flags & VIRTIO_IOMMU_FAULT_F_ADDRESS)
+               dev_err_ratelimited(viommu->dev, "%s fault from EP %u at %#llx [%s%s%s]\n",
+                                   reason_str, endpoint, address,
+                                   flags & VIRTIO_IOMMU_FAULT_F_READ ? "R" : "",
+                                   flags & VIRTIO_IOMMU_FAULT_F_WRITE ? "W" : "",
+                                   flags & VIRTIO_IOMMU_FAULT_F_EXEC ? "X" : "");
+       else
+               dev_err_ratelimited(viommu->dev, "%s fault from EP %u\n",
+                                   reason_str, endpoint);
+       return 0;
+}
+
+static void viommu_event_handler(struct virtqueue *vq)
+{
+       int ret;
+       unsigned int len;
+       struct scatterlist sg[1];
+       struct viommu_event *evt;
+       struct viommu_dev *viommu = vq->vdev->priv;
+
+       while ((evt = virtqueue_get_buf(vq, &len)) != NULL) {
+               if (len > sizeof(*evt)) {
+                       dev_err(viommu->dev,
+                               "invalid event buffer (len %u != %zu)\n",
+                               len, sizeof(*evt));
+               } else if (!(evt->head & VIOMMU_FAULT_RESV_MASK)) {
+                       viommu_fault_handler(viommu, &evt->fault);
+               }
+
+               sg_init_one(sg, evt, sizeof(*evt));
+               ret = virtqueue_add_inbuf(vq, sg, 1, evt, GFP_ATOMIC);
+               if (ret)
+                       dev_err(viommu->dev, "could not add event buffer\n");
+       }
+
+       virtqueue_kick(vq);
+}
+
 /* IOMMU API */
 
 static struct iommu_domain *viommu_domain_alloc(unsigned type)
@@ -886,16 +959,35 @@ static struct iommu_ops viommu_ops = {
 static int viommu_init_vqs(struct viommu_dev *viommu)
 {
        struct virtio_device *vdev = dev_to_virtio(viommu->dev);
-       const char *name = "request";
-       void *ret;
+       const char *names[] = { "request", "event" };
+       vq_callback_t *callbacks[] = {
+               NULL, /* No async requests */
+               viommu_event_handler,
+       };
 
-       ret = virtio_find_single_vq(vdev, NULL, name);
-       if (IS_ERR(ret)) {
-               dev_err(viommu->dev, "cannot find VQ\n");
-               return PTR_ERR(ret);
-       }
+       return virtio_find_vqs(vdev, VIOMMU_NR_VQS, viommu->vqs, callbacks,
+                              names, NULL);
+}
 
-       viommu->vqs[VIOMMU_REQUEST_VQ] = ret;
+static int viommu_fill_evtq(struct viommu_dev *viommu)
+{
+       int i, ret;
+       struct scatterlist sg[1];
+       struct viommu_event *evts;
+       struct virtqueue *vq = viommu->vqs[VIOMMU_EVENT_VQ];
+       size_t nr_evts = vq->num_free;
+
+       viommu->evts = evts = devm_kmalloc_array(viommu->dev, nr_evts,
+                                                sizeof(*evts), GFP_KERNEL);
+       if (!evts)
+               return -ENOMEM;
+
+       for (i = 0; i < nr_evts; i++) {
+               sg_init_one(sg, &evts[i], sizeof(*evts));
+               ret = virtqueue_add_inbuf(vq, sg, 1, &evts[i], GFP_KERNEL);
+               if (ret)
+                       return ret;
+       }
 
        return 0;
 }
@@ -964,6 +1056,11 @@ static int viommu_probe(struct virtio_device *vdev)
 
        virtio_device_ready(vdev);
 
+       /* Populate the event queue with buffers */
+       ret = viommu_fill_evtq(viommu);
+       if (ret)
+               goto err_free_vqs;
+
        ret = iommu_device_sysfs_add(&viommu->iommu, dev, NULL, "%s",
                                     virtio_bus_name(vdev));
        if (ret)

diff --git a/include/uapi/linux/virtio_iommu.h b/include/uapi/linux/virtio_iommu.h
index ae6145cf5928dd723ac760a0188645915c5aea56..ba1b460c9944df383b505ed230a8e611483ace75 100644 (file)
--- a/include/uapi/linux/virtio_iommu.h
+++ b/include/uapi/linux/virtio_iommu.h
@@ -139,4 +139,23 @@ struct virtio_iommu_req_probe {
         */
 };
 
+/* Fault types */
+#define VIRTIO_IOMMU_FAULT_R_UNKNOWN           0
+#define VIRTIO_IOMMU_FAULT_R_DOMAIN            1
+#define VIRTIO_IOMMU_FAULT_R_MAPPING           2
+
+#define VIRTIO_IOMMU_FAULT_F_READ              (1 << 0)
+#define VIRTIO_IOMMU_FAULT_F_WRITE             (1 << 1)
+#define VIRTIO_IOMMU_FAULT_F_EXEC              (1 << 2)
+#define VIRTIO_IOMMU_FAULT_F_ADDRESS           (1 << 8)
+
+struct virtio_iommu_fault {
+       __u8                                    reason;
+       __u8                                    reserved[3];
+       __le32                                  flags;
+       __le32                                  endpoint;
+       __u8                                    reserved2[4];
+       __le64                                  address;
+};
+
 #endif