1 files changed, 139 insertions, 0 deletions
diff --git a/hw/virtio/vhost-shadow-virtqueue.h b/hw/virtio/vhost-shadow-virtqueue.h
new file mode 100644
index 00000000..d04c34a5
--- /dev/null
+++ b/hw/virtio/vhost-shadow-virtqueue.h
@@ -0,0 +1,139 @@
+/*
+ * vhost shadow virtqueue
+ *
+ * SPDX-FileCopyrightText: Red Hat, Inc. 2021
+ * SPDX-FileContributor: Author: Eugenio Pérez <eperezma@redhat.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#ifndef VHOST_SHADOW_VIRTQUEUE_H
+#define VHOST_SHADOW_VIRTQUEUE_H
+
+#include "qemu/event_notifier.h"
+#include "hw/virtio/virtio.h"
+#include "standard-headers/linux/vhost_types.h"
+#include "hw/virtio/vhost-iova-tree.h"
+
+typedef struct SVQDescState {
+    VirtQueueElement *elem;
+
+    /*
+     * Number of descriptors exposed to the device. May or may not match
+     * guest's
+     */
+    unsigned int ndescs;
+} SVQDescState;
+
+typedef struct VhostShadowVirtqueue VhostShadowVirtqueue;
+
+/**
+ * Callback to handle an avail buffer.
+ *
+ * @svq:  Shadow virtqueue
+ * @elem:  Element placed in the queue by the guest
+ * @vq_callback_opaque:  Opaque
+ *
+ * Returns 0 if the vq is running as expected.
+ *
+ * Note that ownership of elem is transferred to the callback.
+ */
+typedef int (*VirtQueueAvailCallback)(VhostShadowVirtqueue *svq,
+                                      VirtQueueElement *elem,
+                                      void *vq_callback_opaque);
+
+typedef struct VhostShadowVirtqueueOps {
+    VirtQueueAvailCallback avail_handler;
+} VhostShadowVirtqueueOps;
+
+/* Shadow virtqueue to relay notifications */
+typedef struct VhostShadowVirtqueue {
+    /* Shadow vring */
+    struct vring vring;
+
+    /* Shadow kick notifier, sent to vhost */
+    EventNotifier hdev_kick;
+    /* Shadow call notifier, sent to vhost */
+    EventNotifier hdev_call;
+
+    /*
+     * Borrowed virtqueue's guest to host notifier. To borrow it in this event
+     * notifier allows to recover the VhostShadowVirtqueue from the event loop
+     * easily. If we use the VirtQueue's one, we don't have an easy way to
+     * retrieve VhostShadowVirtqueue.
+     *
+     * So shadow virtqueue must not clean it, or we would lose VirtQueue one.
+     */
+    EventNotifier svq_kick;
+
+    /* Guest's call notifier, where the SVQ calls guest. */
+    EventNotifier svq_call;
+
+    /* Virtio queue shadowing */
+    VirtQueue *vq;
+
+    /* Virtio device */
+    VirtIODevice *vdev;
+
+    /* IOVA mapping */
+    VhostIOVATree *iova_tree;
+
+    /* SVQ vring descriptors state */
+    SVQDescState *desc_state;
+
+    /* Next VirtQueue element that guest made available */
+    VirtQueueElement *next_guest_avail_elem;
+
+    /*
+     * Backup next field for each descriptor so we can recover securely, not
+     * needing to trust the device access.
+     */
+    uint16_t *desc_next;
+
+    /* Caller callbacks */
+    const VhostShadowVirtqueueOps *ops;
+
+    /* Caller callbacks opaque */
+    void *ops_opaque;
+
+    /* Next head to expose to the device */
+    uint16_t shadow_avail_idx;
+
+    /* Next free descriptor */
+    uint16_t free_head;
+
+    /* Last seen used idx */
+    uint16_t shadow_used_idx;
+
+    /* Next head to consume from the device */
+    uint16_t last_used_idx;
+} VhostShadowVirtqueue;
+
+bool vhost_svq_valid_features(uint64_t features, Error **errp);
+
+void vhost_svq_push_elem(VhostShadowVirtqueue *svq,
+                         const VirtQueueElement *elem, uint32_t len);
+int vhost_svq_add(VhostShadowVirtqueue *svq, const struct iovec *out_sg,
+                  size_t out_num, const struct iovec *in_sg, size_t in_num,
+                  VirtQueueElement *elem);
+size_t vhost_svq_poll(VhostShadowVirtqueue *svq);
+
+void vhost_svq_set_svq_kick_fd(VhostShadowVirtqueue *svq, int svq_kick_fd);
+void vhost_svq_set_svq_call_fd(VhostShadowVirtqueue *svq, int call_fd);
+void vhost_svq_get_vring_addr(const VhostShadowVirtqueue *svq,
+                              struct vhost_vring_addr *addr);
+size_t vhost_svq_driver_area_size(const VhostShadowVirtqueue *svq);
+size_t vhost_svq_device_area_size(const VhostShadowVirtqueue *svq);
+
+void vhost_svq_start(VhostShadowVirtqueue *svq, VirtIODevice *vdev,
+                     VirtQueue *vq);
+void vhost_svq_stop(VhostShadowVirtqueue *svq);
+
+VhostShadowVirtqueue *vhost_svq_new(VhostIOVATree *iova_tree,
+                                    const VhostShadowVirtqueueOps *ops,
+                                    void *ops_opaque);
+
+void vhost_svq_free(gpointer vq);
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(VhostShadowVirtqueue, vhost_svq_free);
+
+#endif