On 2025/01/09 23:13, Willem de Bruijn wrote:
Akihiko Odaki wrote:
They are useful to implement VIRTIO_NET_F_RSS and
VIRTIO_NET_F_HASH_REPORT.
Toeplitz potentially has users beyond virtio. I wonder if we should
from the start implement this as net/core/rss.c.
Or in lib/toeplitz.c just as like lib/siphash.c. I just chose the
easiest option to implement everything in include/linux/virtio_net.h.
Signed-off-by: Akihiko Odaki <akihiko.odaki@xxxxxxxxxx>
---
include/linux/virtio_net.h | 188 +++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 188 insertions(+)
diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h
index 02a9f4dc594d..3b25ca75710b 100644
--- a/include/linux/virtio_net.h
+++ b/include/linux/virtio_net.h
@@ -9,6 +9,194 @@
#include <uapi/linux/tcp.h>
#include <uapi/linux/virtio_net.h>
+struct virtio_net_hash {
+ u32 value;
+ u16 report;
+};
+
+struct virtio_net_toeplitz_state {
+ u32 hash;
+ const u32 *key;
+};
+
+#define VIRTIO_NET_SUPPORTED_HASH_TYPES (VIRTIO_NET_RSS_HASH_TYPE_IPv4 | \
+ VIRTIO_NET_RSS_HASH_TYPE_TCPv4 | \
+ VIRTIO_NET_RSS_HASH_TYPE_UDPv4 | \
+ VIRTIO_NET_RSS_HASH_TYPE_IPv6 | \
+ VIRTIO_NET_RSS_HASH_TYPE_TCPv6 | \
+ VIRTIO_NET_RSS_HASH_TYPE_UDPv6)
+
+#define VIRTIO_NET_RSS_MAX_KEY_SIZE 40
+
+static inline void virtio_net_toeplitz_convert_key(u32 *input, size_t len)
+{
+ while (len >= sizeof(*input)) {
+ *input = be32_to_cpu((__force __be32)*input);
+ input++;
+ len -= sizeof(*input);
+ }
+}
+
+static inline void virtio_net_toeplitz_calc(struct virtio_net_toeplitz_state *state,
+ const __be32 *input, size_t len)
+{
+ while (len >= sizeof(*input)) {
+ for (u32 map = be32_to_cpu(*input); map; map &= (map - 1)) {
+ u32 i = ffs(map);
+
+ state->hash ^= state->key[0] << (32 - i) |
+ (u32)((u64)state->key[1] >> i);
+ }
+
+ state->key++;
+ input++;
+ len -= sizeof(*input);
+ }
+}
Have you verified that this algorithm matches a known toeplitz
implementation. And computes the expected values for the test
inputs in
https://learn.microsoft.com/en-us/windows-hardware/drivers/network/verifying-the-rss-hash-calculation
Yes.
We have a toeplitz implementation in
tools/testing/selftests/net/toeplitz.c that can also be used as
reference.
> >> +
+static inline u8 virtio_net_hash_key_length(u32 types)
+{
+ size_t len = 0;
+
+ if (types & VIRTIO_NET_HASH_REPORT_IPv4)
+ len = max(len,
+ sizeof(struct flow_dissector_key_ipv4_addrs));
+
+ if (types &
+ (VIRTIO_NET_HASH_REPORT_TCPv4 | VIRTIO_NET_HASH_REPORT_UDPv4))
+ len = max(len,
+ sizeof(struct flow_dissector_key_ipv4_addrs) +
+ sizeof(struct flow_dissector_key_ports));
+
+ if (types & VIRTIO_NET_HASH_REPORT_IPv6)
+ len = max(len,
+ sizeof(struct flow_dissector_key_ipv6_addrs));
+
+ if (types &
+ (VIRTIO_NET_HASH_REPORT_TCPv6 | VIRTIO_NET_HASH_REPORT_UDPv6))
+ len = max(len,
+ sizeof(struct flow_dissector_key_ipv6_addrs) +
+ sizeof(struct flow_dissector_key_ports));
+
+ return len + 4;
Avoid magic constants. Please use sizeof or something else to signal
what this 4 derives from.
