[Qemu-devel] [PATCH v5] virtio dataplane: adapt dataplane for virtio Version 1

[Pierre Morel <pmorel@linux.vnet.ibm.com>]

Let dataplane allocate different region for the desc/avail/used
ring regions.
Take VIRTIO_RING_F_EVENT_IDX into account to increase the used/avail
rings accordingly.

Signed-off-by: Pierre Morel <pmorel@linux.vnet.ibm.com>
(changed __virtio16 into uint16_t,
 map descriptor table and available ring read-only)
Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
---

Changes from V4:
- added comments for VIRTIO_RING_F_EVENT_IDX and mapping
- use uint16_t as in ring definitions instead of __virtio16
- map descriptor table and available ring read-only

Changes from V3:
- added changelog

Changes from V2:
- incorporate the code directly in vring_setup().
- added room for the event indexes used with VIRTIO_RING_F_EVENT_IDX

Changes from v1:
- use a macro to gain LOCs inside of vring_setup()

 hw/virtio/dataplane/vring.c         | 66 +++++++++++++++++++++++++++++--------
 include/hw/virtio/dataplane/vring.h |  4 ++-
 2 files changed, 55 insertions(+), 15 deletions(-)

diff --git a/hw/virtio/dataplane/vring.c b/hw/virtio/dataplane/vring.c
index 07fd69c..75db534 100644
--- a/hw/virtio/dataplane/vring.c
+++ b/hw/virtio/dataplane/vring.c
@@ -67,22 +67,50 @@ static void vring_unmap(void *buffer, bool is_write)
 /* Map the guest's vring to host memory */
 bool vring_setup(Vring *vring, VirtIODevice *vdev, int n)
 {
-    hwaddr vring_addr = virtio_queue_get_ring_addr(vdev, n);
-    hwaddr vring_size = virtio_queue_get_ring_size(vdev, n);
-    void *vring_ptr;
+    struct vring *vr = &vring->vr;
+    hwaddr addr;
+    hwaddr size;
+    void *ptr;
 
     vring->broken = false;
-
-    vring_ptr = vring_map(&vring->mr, vring_addr, vring_size, true);
-    if (!vring_ptr) {
-        error_report("Failed to map vring "
-                     "addr %#" HWADDR_PRIx " size %" HWADDR_PRIu,
-                     vring_addr, vring_size);
-        vring->broken = true;
-        return false;
+    vr->num = virtio_queue_get_num(vdev, n);
+
+    addr = virtio_queue_get_desc_addr(vdev, n);
+    size = virtio_queue_get_desc_size(vdev, n);
+    /* Map the descriptor area as read only */
+    ptr = vring_map(&vring->mr_desc, addr, size, false);
+    if (!ptr) {
+        error_report("Failed to map 0x%16lx byte for vring desc at %16lx",
+                      size, addr);
+        goto out_err_desc;
     }
-
-    vring_init(&vring->vr, virtio_queue_get_num(vdev, n), vring_ptr, 4096);
+    vr->desc = ptr;
+
+    addr = virtio_queue_get_avail_addr(vdev, n);
+    size = virtio_queue_get_avail_size(vdev, n);
+    /* Add the size of the used_event_idx */
+    size += sizeof(uint16_t);
+    /* Map the driver area as read only */
+    ptr = vring_map(&vring->mr_avail, addr, size, false);
+    if (!ptr) {
+        error_report("Failed to map 0x%16lx byte for vring avail at %16lx",
+                      size, addr);
+        goto out_err_avail;
+    }
+    vr->avail = ptr;
+
+    addr = virtio_queue_get_used_addr(vdev, n);
+    size = virtio_queue_get_used_size(vdev, n);
+    /* Add the size of the avail_event_idx */
+    size += sizeof(uint16_t);
+    /* Map the device area as read-write */
+    ptr = vring_map(&vring->mr_used, addr, size, true);
+    if (!ptr) {
+        error_report("Failed to map 0x%16lx byte for vring used at %16lx",
+                      size, addr);
+        goto out_err_used;
+    }
+    vr->used = ptr;
 
     vring->last_avail_idx = virtio_queue_get_last_avail_idx(vdev, n);
     vring->last_used_idx = vring_get_used_idx(vdev, vring);
@@ -92,6 +120,14 @@ bool vring_setup(Vring *vring, VirtIODevice *vdev, int n)
     trace_vring_setup(virtio_queue_get_ring_addr(vdev, n),
                       vring->vr.desc, vring->vr.avail, vring->vr.used);
     return true;
+
+out_err_used:
+    memory_region_unref(vring->mr_avail);
+out_err_avail:
+    memory_region_unref(vring->mr_desc);
+out_err_desc:
+    vring->broken = true;
+    return false;
 }
 
 void vring_teardown(Vring *vring, VirtIODevice *vdev, int n)
@@ -99,7 +135,9 @@ void vring_teardown(Vring *vring, VirtIODevice *vdev, int n)
     virtio_queue_set_last_avail_idx(vdev, n, vring->last_avail_idx);
     virtio_queue_invalidate_signalled_used(vdev, n);
 
-    memory_region_unref(vring->mr);
+    memory_region_unref(vring->mr_desc);
+    memory_region_unref(vring->mr_avail);
+    memory_region_unref(vring->mr_used);
 }
 
 /* Disable guest->host notifies */
diff --git a/include/hw/virtio/dataplane/vring.h b/include/hw/virtio/dataplane/vring.h
index 8d97db9..a596e4c 100644
--- a/include/hw/virtio/dataplane/vring.h
+++ b/include/hw/virtio/dataplane/vring.h
@@ -22,7 +22,9 @@
 #include "hw/virtio/virtio.h"
 
 typedef struct {
-    MemoryRegion *mr;               /* memory region containing the vring */
+    MemoryRegion *mr_desc;          /* memory region for the vring desc */
+    MemoryRegion *mr_avail;         /* memory region for the vring avail */
+    MemoryRegion *mr_used;          /* memory region for the vring used */
     struct vring vr;                /* virtqueue vring mapped to host memory */
     uint16_t last_avail_idx;        /* last processed avail ring index */
     uint16_t last_used_idx;         /* last processed used ring index */
-- 
2.3.0