nfp: bpf: add simple map op cache

Each get_next and lookup call requires a round trip to the device.
However, the device is capable of giving us a few entries back,
instead of just one.

In this patch we ask for a small yet reasonable number of entries
(4) on every get_next call, and on subsequent get_next/lookup calls
check this little cache for a hit. The cache is only kept for 250us,
and is invalidated on every operation which may modify the map
(e.g. delete or update call). Note that operations may be performed
simultaneously, so we have to keep track of operations in flight.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

1 files changed, 18 insertions, 0 deletions

diff --git a/drivers/net/ethernet/netronome/nfp/bpf/main.c b/drivers/net/ethernet/netronome/nfp/bpf/main.c
index 2b1773ed3de9..8f732771d3fa 100644
--- a/drivers/net/ethernet/netronome/nfp/bpf/main.c
+++ b/drivers/net/ethernet/netronome/nfp/bpf/main.c
@@ -300,6 +300,14 @@ nfp_bpf_parse_cap_adjust_tail(struct nfp_app_bpf *bpf, void __iomem *value,
 }
 
 static int
+nfp_bpf_parse_cap_cmsg_multi_ent(struct nfp_app_bpf *bpf, void __iomem *value,
+				 u32 length)
+{
+	bpf->cmsg_multi_ent = true;
+	return 0;
+}
+
+static int
 nfp_bpf_parse_cap_abi_version(struct nfp_app_bpf *bpf, void __iomem *value,
 			      u32 length)
 {
@@ -375,6 +383,11 @@ static int nfp_bpf_parse_capabilities(struct nfp_app *app)
 							  length))
 				goto err_release_free;
 			break;
+		case NFP_BPF_CAP_TYPE_CMSG_MULTI_ENT:
+			if (nfp_bpf_parse_cap_cmsg_multi_ent(app->priv, value,
+							     length))
+				goto err_release_free;
+			break;
 		default:
 			nfp_dbg(cpp, "unknown BPF capability: %d\n", type);
 			break;
@@ -426,6 +439,11 @@ static int nfp_bpf_start(struct nfp_app *app)
 		return -EINVAL;
 	}
 
+	if (bpf->cmsg_multi_ent)
+		bpf->cmsg_cache_cnt = nfp_bpf_ctrl_cmsg_cache_cnt(bpf);
+	else
+		bpf->cmsg_cache_cnt = 1;
+
 	return 0;
 }