sched_ext: Maintain an online cid mask in the scheduler arenagrafted

Schedulers on the default cid mapping treat [0, nr_online_cids) as the
online set and restart on hotplug. Schedulers that install their own mapping
with scx_bpf_cid_override() have no way to learn which cids are online: the
count no longer identifies members and the CPU-form cpumask is unusable from
cid programs. This is an obvious hole in the cid API.

Add scx_bpf_online_cmask(), a kernel-maintained cmask in the scheduler's
arena, allocated alongside the per-CPU scratch masks and populated after the
cid mapping is finalized and before ops.init(), for child schedulers too.
The pointer stays valid through ops.exit() with no reference to take. It is
the arena offset as a void pointer, the same form struct_ops arena arguments
arrive in. The verifier types the void return as a scalar for the program's
arena cast.

The mask follows the SCX hotplug notifications: seeded from cpu_active_mask
and updated before ops.cid_online/offline() runs, so it lags cpu_online_mask
only inside a hotplug transition. Updates walk the scheduler list under the
lock that also serializes unlinking. Reads are live, not atomic snapshots.
Root initialization excludes hotplug.

v2: Reworded the getter kerneldoc (Andrea Righi).

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>

1 files changed, 351 insertions, 0 deletions

diff --git a/drivers/net/netdevsim/macsec.c b/drivers/net/netdevsim/macsec.c
new file mode 100644
index 000000000..bdc8020d5
--- /dev/null
+++ b/drivers/net/netdevsim/macsec.c
@@ -0,0 +1,351 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <net/macsec.h>
+#include "netdevsim.h"
+
+static int nsim_macsec_find_secy(struct netdevsim *ns, sci_t sci)
+{
+	int i;
+
+	for (i = 0; i < NSIM_MACSEC_MAX_SECY_COUNT; i++) {
+		if (ns->macsec.nsim_secy[i].sci == sci)
+			return i;
+	}
+
+	return -1;
+}
+
+static int nsim_macsec_find_rxsc(struct nsim_secy *ns_secy, sci_t sci)
+{
+	int i;
+
+	for (i = 0; i < NSIM_MACSEC_MAX_RXSC_COUNT; i++) {
+		if (ns_secy->nsim_rxsc[i].sci == sci)
+			return i;
+	}
+
+	return -1;
+}
+
+static int nsim_macsec_add_secy(struct macsec_context *ctx)
+{
+	struct netdevsim *ns = netdev_priv(ctx->netdev);
+	int idx;
+
+	if (ns->macsec.nsim_secy_count == NSIM_MACSEC_MAX_SECY_COUNT)
+		return -ENOSPC;
+
+	for (idx = 0; idx < NSIM_MACSEC_MAX_SECY_COUNT; idx++) {
+		if (!ns->macsec.nsim_secy[idx].used)
+			break;
+	}
+
+	if (idx == NSIM_MACSEC_MAX_SECY_COUNT) {
+		netdev_err(ctx->netdev, "%s: nsim_secy_count not full but all SecYs used\n",
+			   __func__);
+		return -ENOSPC;
+	}
+
+	netdev_dbg(ctx->netdev, "%s: adding new secy with sci %016llx at index %d\n",
+		   __func__, sci_to_cpu(ctx->secy->sci), idx);
+	ns->macsec.nsim_secy[idx].used = true;
+	ns->macsec.nsim_secy[idx].nsim_rxsc_count = 0;
+	ns->macsec.nsim_secy[idx].sci = ctx->secy->sci;
+	ns->macsec.nsim_secy_count++;
+
+	return 0;
+}
+
+static int nsim_macsec_upd_secy(struct macsec_context *ctx)
+{
+	struct netdevsim *ns = netdev_priv(ctx->netdev);
+	int idx;
+
+	idx = nsim_macsec_find_secy(ns, ctx->secy->sci);
+	if (idx < 0) {
+		netdev_err(ctx->netdev, "%s: sci %016llx not found in secy table\n",
+			   __func__, sci_to_cpu(ctx->secy->sci));
+		return -ENOENT;
+	}
+
+	netdev_dbg(ctx->netdev, "%s: updating secy with sci %016llx at index %d\n",
+		   __func__, sci_to_cpu(ctx->secy->sci), idx);
+
+	return 0;
+}
+
+static int nsim_macsec_del_secy(struct macsec_context *ctx)
+{
+	struct netdevsim *ns = netdev_priv(ctx->netdev);
+	int idx;
+
+	idx = nsim_macsec_find_secy(ns, ctx->secy->sci);
+	if (idx < 0) {
+		netdev_err(ctx->netdev, "%s: sci %016llx not found in secy table\n",
+			   __func__, sci_to_cpu(ctx->secy->sci));
+		return -ENOENT;
+	}
+
+	netdev_dbg(ctx->netdev, "%s: removing SecY with SCI %016llx at index %d\n",
+		   __func__, sci_to_cpu(ctx->secy->sci), idx);
+
+	ns->macsec.nsim_secy[idx].used = false;
+	memset(&ns->macsec.nsim_secy[idx], 0, sizeof(ns->macsec.nsim_secy[idx]));
+	ns->macsec.nsim_secy_count--;
+
+	return 0;
+}
+
+static int nsim_macsec_add_rxsc(struct macsec_context *ctx)
+{
+	struct netdevsim *ns = netdev_priv(ctx->netdev);
+	struct nsim_secy *secy;
+	int idx;
+
+	idx = nsim_macsec_find_secy(ns, ctx->secy->sci);
+	if (idx < 0) {
+		netdev_err(ctx->netdev, "%s: sci %016llx not found in secy table\n",
+			   __func__, sci_to_cpu(ctx->secy->sci));
+		return -ENOENT;
+	}
+	secy = &ns->macsec.nsim_secy[idx];
+
+	if (secy->nsim_rxsc_count == NSIM_MACSEC_MAX_RXSC_COUNT)
+		return -ENOSPC;
+
+	for (idx = 0; idx < NSIM_MACSEC_MAX_RXSC_COUNT; idx++) {
+		if (!secy->nsim_rxsc[idx].used)
+			break;
+	}
+
+	if (idx == NSIM_MACSEC_MAX_RXSC_COUNT)
+		netdev_err(ctx->netdev, "%s: nsim_rxsc_count not full but all RXSCs used\n",
+			   __func__);
+
+	netdev_dbg(ctx->netdev, "%s: adding new rxsc with sci %016llx at index %d\n",
+		   __func__, sci_to_cpu(ctx->rx_sc->sci), idx);
+	secy->nsim_rxsc[idx].used = true;
+	secy->nsim_rxsc[idx].sci = ctx->rx_sc->sci;
+	secy->nsim_rxsc_count++;
+
+	return 0;
+}
+
+static int nsim_macsec_upd_rxsc(struct macsec_context *ctx)
+{
+	struct netdevsim *ns = netdev_priv(ctx->netdev);
+	struct nsim_secy *secy;
+	int idx;
+
+	idx = nsim_macsec_find_secy(ns, ctx->secy->sci);
+	if (idx < 0) {
+		netdev_err(ctx->netdev, "%s: sci %016llx not found in secy table\n",
+			   __func__, sci_to_cpu(ctx->secy->sci));
+		return -ENOENT;
+	}
+	secy = &ns->macsec.nsim_secy[idx];
+
+	idx = nsim_macsec_find_rxsc(secy, ctx->rx_sc->sci);
+	if (idx < 0) {
+		netdev_err(ctx->netdev, "%s: sci %016llx not found in RXSC table\n",
+			   __func__, sci_to_cpu(ctx->rx_sc->sci));
+		return -ENOENT;
+	}
+
+	netdev_dbg(ctx->netdev, "%s: updating RXSC with sci %016llx at index %d\n",
+		   __func__, sci_to_cpu(ctx->rx_sc->sci), idx);
+
+	return 0;
+}
+
+static int nsim_macsec_del_rxsc(struct macsec_context *ctx)
+{
+	struct netdevsim *ns = netdev_priv(ctx->netdev);
+	struct nsim_secy *secy;
+	int idx;
+
+	idx = nsim_macsec_find_secy(ns, ctx->secy->sci);
+	if (idx < 0) {
+		netdev_err(ctx->netdev, "%s: sci %016llx not found in secy table\n",
+			   __func__, sci_to_cpu(ctx->secy->sci));
+		return -ENOENT;
+	}
+	secy = &ns->macsec.nsim_secy[idx];
+
+	idx = nsim_macsec_find_rxsc(secy, ctx->rx_sc->sci);
+	if (idx < 0) {
+		netdev_err(ctx->netdev, "%s: sci %016llx not found in RXSC table\n",
+			   __func__, sci_to_cpu(ctx->rx_sc->sci));
+		return -ENOENT;
+	}
+
+	netdev_dbg(ctx->netdev, "%s: removing RXSC with sci %016llx at index %d\n",
+		   __func__, sci_to_cpu(ctx->rx_sc->sci), idx);
+
+	secy->nsim_rxsc[idx].used = false;
+	memset(&secy->nsim_rxsc[idx], 0, sizeof(secy->nsim_rxsc[idx]));
+	secy->nsim_rxsc_count--;
+
+	return 0;
+}
+
+static int nsim_macsec_add_rxsa(struct macsec_context *ctx)
+{
+	struct netdevsim *ns = netdev_priv(ctx->netdev);
+	struct nsim_secy *secy;
+	int idx;
+
+	idx = nsim_macsec_find_secy(ns, ctx->secy->sci);
+	if (idx < 0) {
+		netdev_err(ctx->netdev, "%s: sci %016llx not found in secy table\n",
+			   __func__, sci_to_cpu(ctx->secy->sci));
+		return -ENOENT;
+	}
+	secy = &ns->macsec.nsim_secy[idx];
+
+	idx = nsim_macsec_find_rxsc(secy, ctx->sa.rx_sa->sc->sci);
+	if (idx < 0) {
+		netdev_err(ctx->netdev, "%s: sci %016llx not found in RXSC table\n",
+			   __func__, sci_to_cpu(ctx->sa.rx_sa->sc->sci));
+		return -ENOENT;
+	}
+
+	netdev_dbg(ctx->netdev, "%s: RXSC with sci %016llx, AN %u\n",
+		   __func__, sci_to_cpu(ctx->sa.rx_sa->sc->sci), ctx->sa.assoc_num);
+
+	return 0;
+}
+
+static int nsim_macsec_upd_rxsa(struct macsec_context *ctx)
+{
+	struct netdevsim *ns = netdev_priv(ctx->netdev);
+	struct nsim_secy *secy;
+	int idx;
+
+	idx = nsim_macsec_find_secy(ns, ctx->secy->sci);
+	if (idx < 0) {
+		netdev_err(ctx->netdev, "%s: sci %016llx not found in secy table\n",
+			   __func__, sci_to_cpu(ctx->secy->sci));
+		return -ENOENT;
+	}
+	secy = &ns->macsec.nsim_secy[idx];
+
+	idx = nsim_macsec_find_rxsc(secy, ctx->sa.rx_sa->sc->sci);
+	if (idx < 0) {
+		netdev_err(ctx->netdev, "%s: sci %016llx not found in RXSC table\n",
+			   __func__, sci_to_cpu(ctx->sa.rx_sa->sc->sci));
+		return -ENOENT;
+	}
+
+	netdev_dbg(ctx->netdev, "%s: RXSC with sci %016llx, AN %u\n",
+		   __func__, sci_to_cpu(ctx->sa.rx_sa->sc->sci), ctx->sa.assoc_num);
+
+	return 0;
+}
+
+static int nsim_macsec_del_rxsa(struct macsec_context *ctx)
+{
+	struct netdevsim *ns = netdev_priv(ctx->netdev);
+	struct nsim_secy *secy;
+	int idx;
+
+	idx = nsim_macsec_find_secy(ns, ctx->secy->sci);
+	if (idx < 0) {
+		netdev_err(ctx->netdev, "%s: sci %016llx not found in secy table\n",
+			   __func__, sci_to_cpu(ctx->secy->sci));
+		return -ENOENT;
+	}
+	secy = &ns->macsec.nsim_secy[idx];
+
+	idx = nsim_macsec_find_rxsc(secy, ctx->sa.rx_sa->sc->sci);
+	if (idx < 0) {
+		netdev_err(ctx->netdev, "%s: sci %016llx not found in RXSC table\n",
+			   __func__, sci_to_cpu(ctx->sa.rx_sa->sc->sci));
+		return -ENOENT;
+	}
+
+	netdev_dbg(ctx->netdev, "%s: RXSC with sci %016llx, AN %u\n",
+		   __func__, sci_to_cpu(ctx->sa.rx_sa->sc->sci), ctx->sa.assoc_num);
+
+	return 0;
+}
+
+static int nsim_macsec_add_txsa(struct macsec_context *ctx)
+{
+	struct netdevsim *ns = netdev_priv(ctx->netdev);
+	int idx;
+
+	idx = nsim_macsec_find_secy(ns, ctx->secy->sci);
+	if (idx < 0) {
+		netdev_err(ctx->netdev, "%s: sci %016llx not found in secy table\n",
+			   __func__, sci_to_cpu(ctx->secy->sci));
+		return -ENOENT;
+	}
+
+	netdev_dbg(ctx->netdev, "%s: SECY with sci %016llx, AN %u\n",
+		   __func__, sci_to_cpu(ctx->secy->sci), ctx->sa.assoc_num);
+
+	return 0;
+}
+
+static int nsim_macsec_upd_txsa(struct macsec_context *ctx)
+{
+	struct netdevsim *ns = netdev_priv(ctx->netdev);
+	int idx;
+
+	idx = nsim_macsec_find_secy(ns, ctx->secy->sci);
+	if (idx < 0) {
+		netdev_err(ctx->netdev, "%s: sci %016llx not found in secy table\n",
+			   __func__, sci_to_cpu(ctx->secy->sci));
+		return -ENOENT;
+	}
+
+	netdev_dbg(ctx->netdev, "%s: SECY with sci %016llx, AN %u\n",
+		   __func__, sci_to_cpu(ctx->secy->sci), ctx->sa.assoc_num);
+
+	return 0;
+}
+
+static int nsim_macsec_del_txsa(struct macsec_context *ctx)
+{
+	struct netdevsim *ns = netdev_priv(ctx->netdev);
+	int idx;
+
+	idx = nsim_macsec_find_secy(ns, ctx->secy->sci);
+	if (idx < 0) {
+		netdev_err(ctx->netdev, "%s: sci %016llx not found in secy table\n",
+			   __func__, sci_to_cpu(ctx->secy->sci));
+		return -ENOENT;
+	}
+
+	netdev_dbg(ctx->netdev, "%s: SECY with sci %016llx, AN %u\n",
+		   __func__, sci_to_cpu(ctx->secy->sci), ctx->sa.assoc_num);
+
+	return 0;
+}
+
+static const struct macsec_ops nsim_macsec_ops = {
+	.mdo_add_secy = nsim_macsec_add_secy,
+	.mdo_upd_secy = nsim_macsec_upd_secy,
+	.mdo_del_secy = nsim_macsec_del_secy,
+	.mdo_add_rxsc = nsim_macsec_add_rxsc,
+	.mdo_upd_rxsc = nsim_macsec_upd_rxsc,
+	.mdo_del_rxsc = nsim_macsec_del_rxsc,
+	.mdo_add_rxsa = nsim_macsec_add_rxsa,
+	.mdo_upd_rxsa = nsim_macsec_upd_rxsa,
+	.mdo_del_rxsa = nsim_macsec_del_rxsa,
+	.mdo_add_txsa = nsim_macsec_add_txsa,
+	.mdo_upd_txsa = nsim_macsec_upd_txsa,
+	.mdo_del_txsa = nsim_macsec_del_txsa,
+};
+
+void nsim_macsec_init(struct netdevsim *ns)
+{
+	ns->netdev->macsec_ops = &nsim_macsec_ops;
+	ns->netdev->features |= NETIF_F_HW_MACSEC;
+	memset(&ns->macsec, 0, sizeof(ns->macsec));
+}
+
+void nsim_macsec_teardown(struct netdevsim *ns)
+{
+}