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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Woojung Huh , UNGLinuxDriver@microchip.com, netdev@vger.kernel.org Subject: Re: [PATCH net v3 5/5] net: dsa: ks8995: Implement port isolation Message-ID: <20260220184547.o7ygnl4aiu2jufao@skbuf> References: <20260219-ks8995-fixups-v3-0-a7fc63fe1916@kernel.org> <20260219-ks8995-fixups-v3-0-a7fc63fe1916@kernel.org> <20260219-ks8995-fixups-v3-5-a7fc63fe1916@kernel.org> <20260219-ks8995-fixups-v3-5-a7fc63fe1916@kernel.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260219-ks8995-fixups-v3-5-a7fc63fe1916@kernel.org> <20260219-ks8995-fixups-v3-5-a7fc63fe1916@kernel.org> Hi Linus, Some excerpts from AI review which I considered relevant. On Thu, Feb 19, 2026 at 03:24:21PM +0100, Linus Walleij wrote: > It is unsound to not have proper port isolation on a > switch which supports it. > > Set each port as isolated by default in the setup callback > and de-isolate and isolate the ports in the bridge join/leave > callbacks. > > Fixes: a7fe8b266f65 ("net: dsa: ks8995: Add basic switch set-up") > Reported-by: Vladimir Oltean > Signed-off-by: Linus Walleij > --- > drivers/net/dsa/ks8995.c | 131 ++++++++++++++++++++++++++++++++++++++++++++++- > 1 file changed, 129 insertions(+), 2 deletions(-) > > diff --git a/drivers/net/dsa/ks8995.c b/drivers/net/dsa/ks8995.c > index 1ed81a8f7d21..dbae218fb015 100644 > --- a/drivers/net/dsa/ks8995.c > +++ b/drivers/net/dsa/ks8995.c > @@ -80,6 +80,11 @@ > #define KS8995_PC0_TAG_REM BIT(1) /* Enable tag removal on port */ > #define KS8995_PC0_PRIO_EN BIT(0) /* Enable priority handling */ > > +#define KS8995_PC1_SNIFF_PORT BIT(7) /* This port is a sniffer port */ > +#define KS8995_PC1_RCV_SNIFF BIT(6) /* Packets received goes to sniffer port(s) */ > +#define KS8995_PC1_XMIT_SNIFF BIT(5) /* Packets transmitted goes to sniffer port(s) */ > +#define KS8995_PC1_PORT_VLAN GENMASK(4, 0) /* Port isolation mask */ > + > #define KS8995_PC2_TXEN BIT(2) /* Enable TX on port */ > #define KS8995_PC2_RXEN BIT(1) /* Enable RX on port */ > #define KS8995_PC2_LEARN_DIS BIT(0) /* Disable learning on port */ > @@ -441,6 +446,44 @@ dsa_tag_protocol ks8995_get_tag_protocol(struct dsa_switch *ds, > > static int ks8995_setup(struct dsa_switch *ds) > { > + struct ks8995_switch *ks = ds->priv; > + int ret; > + u8 val; > + int i; > + > + /* Isolate all user ports so they can only send packets to itself and the CPU port */ This isn't a bug, but the comment terminology might be clearer. The use of "isolation" could be confused with the BR_ISOLATED bridge port flag (from "man bridge", isolated bridge ports "will be able to communicate with non-isolated ports only"). Vladimir Oltean recommended avoiding "isolation" related terminology for user port separation in v2. Reference: https://lore.kernel.org/netdev/20260119224805.hjvh5xdjfhd6c6kf@skbuf/ [ you walked past most of my review comments on v2 with no pushback as to why you won't apply them ] > + for (i = 0; i < KS8995_CPU_PORT; i++) { > + ret = ks8995_read_reg(ks, KS8995_REG_PC(i, KS8995_REG_PC1), &val); > + if (ret) { > + dev_err(ks->dev, "failed to read KS8995_REG_PC1 on port %d\n", i); > + return ret; > + } Do you need to perform a register read at probe time, or could you just call ks8995_write_reg() with known good values for the sniff port bits too? Vladimir Oltean questioned this in v2. > + > + val &= ~KS8995_PC1_PORT_VLAN; > + val |= (BIT(i) | BIT(KS8995_CPU_PORT)); > + > + ret = ks8995_write_reg(ks, KS8995_REG_PC(i, KS8995_REG_PC1), val); > + if (ret) { > + dev_err(ks->dev, "failed to write KS8995_REG_PC1 on port %d\n", i); > + return ret; > + } > + } > + > + /* The CPU port should be able to talk to all ports */ > + ret = ks8995_read_reg(ks, KS8995_REG_PC(KS8995_CPU_PORT, KS8995_REG_PC1), &val); > + if (ret) { > + dev_err(ks->dev, "failed to read KS8995_REG_PC1 on CPU port\n"); > + return ret; > + } > + > + val |= KS8995_PC1_PORT_VLAN; Does this enable hairpinning on the CPU port? Writing KS8995_PC1_PORT_VLAN (GENMASK(4, 0)) includes KS8995_CPU_PORT (4), which would enable reflection of forwarded traffic on the CPU port. Vladimir Oltean raised this concern in v2. > + > + ret = ks8995_write_reg(ks, KS8995_REG_PC(KS8995_CPU_PORT, KS8995_REG_PC1), val); > + if (ret) { > + dev_err(ks->dev, "failed to write KS8995_REG_PC1 on CPU port\n"); > + return ret; > + } > + > return 0; > } > > @@ -466,8 +509,44 @@ static int ks8995_port_bridge_join(struct dsa_switch *ds, int port, > bool *tx_fwd_offload, > struct netlink_ext_ack *extack) > { > + struct ks8995_switch *ks = ds->priv; > + u8 port_bitmap = 0; > + int ret; > + u8 val; > + int i; > + > + /* De-isolate this port from any other port on the bridge */ > + port_bitmap |= BIT(port); > + for (i = 0; i < KS8995_CPU_PORT; i++) { > + if (i == port) > + continue; > + if (!dsa_port_offloads_bridge(dsa_to_port(ds, i), &bridge)) > + continue; > + port_bitmap |= BIT(i); > + } > + > + /* Update all affected ports with the new bitmask */ > + for (i = 0; i < KS8995_CPU_PORT; i++) { > + if (!dsa_port_offloads_bridge(dsa_to_port(ds, i), &bridge)) > + continue; > + > + ret = ks8995_read_reg(ks, KS8995_REG_PC(i, KS8995_REG_PC1), &val); > + if (ret) { > + dev_err(ks->dev, "failed to read KS8995_REG_PC1 on port %d\n", i); > + return ret; > + } > + > + val |= port_bitmap; Can this create a hairpinning problem? When a new port joins a bridge, the existing ports start enabling forwarding to themselves as well since dsa_port_offloads_bridge() returns true for the currently joining port, and the port_bitmap written to port i contains BIT(i) set. Vladimir Oltean raised this concern in v2. > + > + ret = ks8995_write_reg(ks, KS8995_REG_PC(i, KS8995_REG_PC1), val); > + if (ret) { > + dev_err(ks->dev, "failed to write KS8995_REG_PC1 on port %d\n", i); > + return ret; > + } > + } > + > /* port_stp_state_set() will be called after to put the port in > - * appropriate state so there is no need to do anything. > + * appropriate state. > */ > > return 0; > @@ -476,8 +555,56 @@ static int ks8995_port_bridge_join(struct dsa_switch *ds, int port, > static void ks8995_port_bridge_leave(struct dsa_switch *ds, int port, > struct dsa_bridge bridge) > { > + struct ks8995_switch *ks = ds->priv; > + u8 port_bitmap = 0; > + int ret; > + u8 val; > + int i; > + > + /* Isolate this port from any other port on the bridge */ > + for (i = 0; i < KS8995_CPU_PORT; i++) { > + /* Current port handled last */ > + if (i == port) > + continue; > + /* Not on this bridge */ > + if (!dsa_port_offloads_bridge(dsa_to_port(ds, i), &bridge)) > + continue; > + > + ret = ks8995_read_reg(ks, KS8995_REG_PC(i, KS8995_REG_PC1), &val); > + if (ret) { > + dev_err(ks->dev, "failed to read KS8995_REG_PC1 on port %d\n", i); > + return; > + } > + > + val &= ~BIT(port); > + > + ret = ks8995_write_reg(ks, KS8995_REG_PC(i, KS8995_REG_PC1), val); > + if (ret) { > + dev_err(ks->dev, "failed to write KS8995_REG_PC1 on port %d\n", i); > + return; > + } > + > + /* Accumulate this port for access by current */ > + port_bitmap |= BIT(i); > + } > + > + /* Isolate this port from all other ports formerly on the bridge */ > + ret = ks8995_read_reg(ks, KS8995_REG_PC(port, KS8995_REG_PC1), &val); > + if (ret) { > + dev_err(ks->dev, "failed to read KS8995_REG_PC1 on port %d\n", port); > + return; > + } > + > + val &= ~port_bitmap; > + > + ret = ks8995_write_reg(ks, KS8995_REG_PC(port, KS8995_REG_PC1), val); > + if (ret) { > + dev_err(ks->dev, "failed to write KS8995_REG_PC1 on port %d\n", port); > + return; > + } > + > /* port_stp_state_set() will be called after to put the port in > - * forwarding state so there is no need to do anything. > + * forwarding state. > */ > } > > > -- > 2.53.0 >