* [RFC PATCH 1/2] vdpa: Restore hash calculation state
2023-08-11 14:50 [RFC PATCH 0/2] Vhost-vdpa Shadow Virtqueue Hash calculation Support Hawkins Jiawei
@ 2023-08-11 14:50 ` Hawkins Jiawei
2023-08-11 14:58 ` [RFC PATCH 2/2] vdpa: Allow VIRTIO_NET_F_HASH_REPORT in SVQ Hawkins Jiawei
1 sibling, 0 replies; 3+ messages in thread
From: Hawkins Jiawei @ 2023-08-11 14:50 UTC (permalink / raw)
To: jasowang, mst, eperezma
Cc: qemu-devel, yin31149, 18801353760, yuri.benditovich
This patch introduces vhost_vdpa_net_load_rss() to restore
the hash calculation state at device's startup.
Note that vhost_vdpa_net_load_rss() has `do_rss` argument,
which allows future code to reuse this function to restore
the receive-side scaling state when the VIRTIO_NET_F_RSS
feature is enabled in SVQ. Currently, vhost_vdpa_net_load_rss()
could only be invoked when `do_rss` is set to false.
Signed-off-by: Hawkins Jiawei <yin31149@gmail.com>
---
Question:
It seems that virtio_net_handle_rss() currently does not restore the
hash key length parsed from the CVQ command sent from the guest into
n->rss_data and uses the maximum key length in other code.
So for `hash_key_length` field in VIRTIO_NET_CTRL_MQ_HASH_CONFIG command
sent to device, is it okay to also use the maximum key length as its value?
Or should we introduce the `hash_key_length` field in n->rss_data
structure to record the key length from guest and use this value?
net/vhost-vdpa.c | 88 ++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 88 insertions(+)
diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
index 7bb29f6009..bd51020771 100644
--- a/net/vhost-vdpa.c
+++ b/net/vhost-vdpa.c
@@ -788,6 +788,85 @@ static int vhost_vdpa_net_load_mac(VhostVDPAState *s, const VirtIONet *n,
return 0;
}
+static int vhost_vdpa_net_load_rss(VhostVDPAState *s, const VirtIONet *n,
+ void **out_cursor, void **in_cursor,
+ bool do_rss)
+{
+ struct virtio_net_rss_config cfg;
+ ssize_t r;
+
+ /*
+ * According to VirtIO standard, "Initially the device has all hash
+ * types disabled and reports only VIRTIO_NET_HASH_REPORT_NONE.".
+ *
+ * Therefore, there is no need to send this CVQ command if the
+ * driver disable the all hash types, which aligns with
+ * the device's defaults.
+ *
+ * Note that the device's defaults can mismatch the driver's
+ * configuration only at live migration.
+ */
+ if (!n->rss_data.enabled ||
+ n->rss_data.hash_types == VIRTIO_NET_HASH_REPORT_NONE) {
+ return 0;
+ }
+
+ cfg.hash_types = cpu_to_le32(n->rss_data.hash_types);
+ /*
+ * According to VirtIO standard, "Field reserved MUST contain zeroes.
+ * It is defined to make the structure to match the layout of
+ * virtio_net_rss_config structure, defined in 5.1.6.5.7.".
+ *
+ * Therefore, we need to zero the fields in struct virtio_net_rss_config,
+ * which corresponds the `reserved` field in
+ * struct virtio_net_hash_config.
+ */
+ memset(&cfg.indirection_table_mask, 0,
+ sizeof_field(struct virtio_net_hash_config, reserved));
+ /*
+ * Consider that virtio_net_handle_rss() currently does not restore the
+ * hash key length parsed from the CVQ command sent from the guest into
+ * n->rss_data and uses the maximum key length in other code, so we also
+ * employthe the maxium key length here.
+ */
+ cfg.hash_key_length = sizeof(n->rss_data.key);
+
+ g_autofree uint16_t *table = g_malloc_n(n->rss_data.indirections_len,
+ sizeof(n->rss_data.indirections_table[0]));
+ for (int i = 0; i < n->rss_data.indirections_len; ++i) {
+ table[i] = cpu_to_le16(n->rss_data.indirections_table[i]);
+ }
+
+ const struct iovec data[] = {
+ {
+ .iov_base = &cfg,
+ .iov_len = offsetof(struct virtio_net_rss_config,
+ indirection_table),
+ }, {
+ .iov_base = table,
+ .iov_len = n->rss_data.indirections_len *
+ sizeof(n->rss_data.indirections_table[0]),
+ }, {
+ .iov_base = &cfg.max_tx_vq,
+ .iov_len = offsetof(struct virtio_net_rss_config, hash_key_data) -
+ offsetof(struct virtio_net_rss_config, max_tx_vq),
+ }, {
+ .iov_base = (void *)n->rss_data.key,
+ .iov_len = sizeof(n->rss_data.key),
+ }
+ };
+
+ r = vhost_vdpa_net_load_cmd(s, out_cursor, in_cursor,
+ VIRTIO_NET_CTRL_MQ,
+ VIRTIO_NET_CTRL_MQ_HASH_CONFIG,
+ data, ARRAY_SIZE(data));
+ if (unlikely(r < 0)) {
+ return r;
+ }
+
+ return 0;
+}
+
static int vhost_vdpa_net_load_mq(VhostVDPAState *s,
const VirtIONet *n,
void **out_cursor, void **in_cursor)
@@ -812,6 +891,15 @@ static int vhost_vdpa_net_load_mq(VhostVDPAState *s,
return r;
}
+ if (!virtio_vdev_has_feature(&n->parent_obj, VIRTIO_NET_F_HASH_REPORT)) {
+ return 0;
+ }
+
+ r = vhost_vdpa_net_load_rss(s, n, out_cursor, in_cursor, false);
+ if (unlikely(r < 0)) {
+ return r;
+ }
+
return 0;
}
--
2.25.1
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