Re: [dpdk-dev] [PATCH v9 1/8] net/virtio: vring init for packed queues

[Maxime Coquelin]

On 10/25/18 3:48 PM, Jens Freimann wrote:

On Thu, Oct 25, 2018 at 05:21:15PM +0800, Tiwei Bie wrote:

On Wed, Oct 24, 2018 at 04:32:29PM +0200, Jens Freimann wrote:

Add and initialize descriptor data structures.

Signed-off-by: Jens Freimann <jfreim...@redhat.com>
---
 drivers/net/virtio/virtio_ethdev.c | 18 ++++----
 drivers/net/virtio/virtio_pci.h    |  7 +++
 drivers/net/virtio/virtio_ring.h   | 74 ++++++++++++++++++++++++++----
 drivers/net/virtio/virtqueue.h     | 15 +++++-
 4 files changed, 95 insertions(+), 19 deletions(-)

diff --git a/drivers/net/virtio/virtio_ethdev.c b/drivers/net/virtio/virtio_ethdev.c

index 730c41707..6130aef16 100644
--- a/drivers/net/virtio/virtio_ethdev.c
+++ b/drivers/net/virtio/virtio_ethdev.c
@@ -299,19 +299,21 @@ virtio_init_vring(struct virtqueue *vq)

     PMD_INIT_FUNC_TRACE();

-    /*

-     * Reinitialise since virtio port might have been stopped and restarted

-     */

Why above comments are removed?

by mistake, I'll put them back in next version.

     memset(ring_mem, 0, vq->vq_ring_size);
-    vring_init(vr, size, ring_mem, VIRTIO_PCI_VRING_ALIGN);
+    vring_init(vq->hw, vr, size, ring_mem, VIRTIO_PCI_VRING_ALIGN);
+
     vq->vq_used_cons_idx = 0;
     vq->vq_desc_head_idx = 0;
     vq->vq_avail_idx = 0;
     vq->vq_desc_tail_idx = (uint16_t)(vq->vq_nentries - 1);
     vq->vq_free_cnt = vq->vq_nentries;

     memset(vq->vq_descx, 0, sizeof(struct vq_desc_extra) * vq->vq_nentries);

-
-    vring_desc_init(vr->desc, size);
+    if (vtpci_packed_queue(vq->hw)) {
+        if (!vtpci_with_feature(vq->hw, VIRTIO_F_IN_ORDER))
+            vring_desc_init_packed(vq, size);

Don't we need to initialize descs in IN-ORDER case?

Yes, I missed this here. I'll fix it.

+    } else {
+        vring_desc_init_split(vr->desc, size);
+    }

     /*
      * Disable device(host) interrupting guest

@@ -386,7 +388,7 @@ virtio_init_queue(struct rte_eth_dev *dev, uint16_t vtpci_queue_idx)

     /*
      * Reserve a memzone for vring elements
      */
-    size = vring_size(vq_size, VIRTIO_PCI_VRING_ALIGN);
+    size = vring_size(hw, vq_size, VIRTIO_PCI_VRING_ALIGN);
     vq->vq_ring_size = RTE_ALIGN_CEIL(size, VIRTIO_PCI_VRING_ALIGN);
     PMD_INIT_LOG(DEBUG, "vring_size: %d, rounded_vring_size: %d",
              size, vq->vq_ring_size);

@@ -489,7 +491,7 @@ virtio_init_queue(struct rte_eth_dev *dev, uint16_t vtpci_queue_idx)

         for (i = 0; i < vq_size; i++) {
             struct vring_desc *start_dp = txr[i].tx_indir;

-            vring_desc_init(start_dp, RTE_DIM(txr[i].tx_indir));
+            vring_desc_init_split(start_dp, RTE_DIM(txr[i].tx_indir));

             /* first indirect descriptor is always the tx header */
             start_dp->addr = txvq->virtio_net_hdr_mem

diff --git a/drivers/net/virtio/virtio_pci.h b/drivers/net/virtio/virtio_pci.h

index 58fdd3d45..c487d2be0 100644
--- a/drivers/net/virtio/virtio_pci.h
+++ b/drivers/net/virtio/virtio_pci.h
@@ -113,6 +113,7 @@ struct virtnet_ctl;

 #define VIRTIO_F_VERSION_1        32
 #define VIRTIO_F_IOMMU_PLATFORM    33
+#define VIRTIO_F_RING_PACKED        34

 /*
  * Some VirtIO feature bits (currently bits 28 through 31) are

@@ -314,6 +315,12 @@ vtpci_with_feature(struct virtio_hw *hw, uint64_t bit)

     return (hw->guest_features & (1ULL << bit)) != 0;
 }

+static inline int
+vtpci_packed_queue(struct virtio_hw *hw)
+{
+    return vtpci_with_feature(hw, VIRTIO_F_RING_PACKED);
+}
+
 /*
  * Function declaration from virtio_pci.c
  */

diff --git a/drivers/net/virtio/virtio_ring.h b/drivers/net/virtio/virtio_ring.h

index 9e3c2a015..e65da100b 100644
--- a/drivers/net/virtio/virtio_ring.h
+++ b/drivers/net/virtio/virtio_ring.h
@@ -54,11 +54,38 @@ struct vring_used {
     struct vring_used_elem ring[0];
 };

+/* For support of packed virtqueues in Virtio 1.1 the format of descriptors

+ * looks like this.
+ */
+struct vring_desc_packed {
+    uint64_t addr;
+    uint32_t len;
+    uint16_t index;

s/index/id/

ok

+    uint16_t flags;
+} __attribute__ ((aligned(16)));

We don't need the "__attribute__ ((aligned(16)))" in descriptor
structure's definition.

Someone requested this in an earlier round of reviews, but I'll
check again.

+
+#define RING_EVENT_FLAGS_ENABLE 0x0
+#define RING_EVENT_FLAGS_DISABLE 0x1
+#define RING_EVENT_FLAGS_DESC 0x2

Please add an empty line here.

ok

+struct vring_packed_desc_event {
+    uint16_t desc_event_off_wrap;
+    uint16_t desc_event_flags;
+};
+
 struct vring {
     unsigned int num;
-    struct vring_desc  *desc;
-    struct vring_avail *avail;
-    struct vring_used  *used;
+    union {
+        struct vring_desc_packed *desc_packed;
+        struct vring_desc *desc;
+    };
+    union {
+        struct vring_avail *avail;
+        struct vring_packed_desc_event *driver_event;
+    };
+    union {
+        struct vring_used  *used;
+        struct vring_packed_desc_event *device_event;
+    };
 };

We should define a new `vring` structure for packed ring.

I think it was requested to have it as a union before, but I can do
it.

I guess oyu vcan have a union between struct vring and struct
vring_packed?

Thanks for your review!

regards,
Jens

Thanks