| Message ID | 20210830214859.403100-6-linus.walleij@linaro.org |
|---|---|
| State | Superseded |
| Headers | show |
| Series | RTL8366RB improvements | expand |
On Mon, Aug 30, 2021 at 11:48:59PM +0200, Linus Walleij wrote: > This implements fast aging per-port using the special "security" > register, which will flush any L2 LUTs on a port. > > Suggested-by: Vladimir Oltean <olteanv@gmail.com> > Cc: Alvin Šipraga <alsi@bang-olufsen.dk> > Cc: Mauri Sandberg <sandberg@mailfence.com> > Cc: DENG Qingfang <dqfext@gmail.com> > Signed-off-by: Linus Walleij <linus.walleij@linaro.org> > --- > ChangeLog v1->v2: > - New patch suggested by Vladimir. > --- > drivers/net/dsa/rtl8366rb.c | 14 ++++++++++++++ > 1 file changed, 14 insertions(+) > > diff --git a/drivers/net/dsa/rtl8366rb.c b/drivers/net/dsa/rtl8366rb.c > index 4cb0e336ce6b..548282119cc4 100644 > --- a/drivers/net/dsa/rtl8366rb.c > +++ b/drivers/net/dsa/rtl8366rb.c > @@ -1219,6 +1219,19 @@ rtl8366rb_port_bridge_flags(struct dsa_switch *ds, int port, > return 0; > } > > +static void > +rtl8366rb_port_fast_age(struct dsa_switch *ds, int port) > +{ > + struct realtek_smi *smi = ds->priv; > + > + /* This will age out any L2 entries */ Clarify "any L2 entries". The fdb flushing process should remove the dynamically learned FDB entries, it should keep the static ones. Did you say "any" because rtl8366rb does not implement static FDB entries via .port_fdb_add, and therefore all entries are dynamic, or does it really delete static FDB entries? > + regmap_update_bits(smi->map, RTL8366RB_SECURITY_CTRL, > + BIT(port), BIT(port)); > + /* Restore the normal state of things */ > + regmap_update_bits(smi->map, RTL8366RB_SECURITY_CTRL, > + BIT(port), 0); > +} > + > static int > rtl8366rb_port_bridge_join(struct dsa_switch *ds, int port, > struct net_device *bridge) > @@ -1673,6 +1686,7 @@ static const struct dsa_switch_ops rtl8366rb_switch_ops = { > .port_disable = rtl8366rb_port_disable, > .port_pre_bridge_flags = rtl8366rb_port_pre_bridge_flags, > .port_bridge_flags = rtl8366rb_port_bridge_flags, > + .port_fast_age = rtl8366rb_port_fast_age, > .port_change_mtu = rtl8366rb_change_mtu, > .port_max_mtu = rtl8366rb_max_mtu, > }; > -- > 2.31.1 >
On 8/30/21 11:48 PM, Linus Walleij wrote: > This implements fast aging per-port using the special "security" > register, which will flush any L2 LUTs on a port. > > Suggested-by: Vladimir Oltean <olteanv@gmail.com> > Cc: Alvin Šipraga <alsi@bang-olufsen.dk> > Cc: Mauri Sandberg <sandberg@mailfence.com> > Cc: DENG Qingfang <dqfext@gmail.com> > Signed-off-by: Linus Walleij <linus.walleij@linaro.org> > --- Vladimir is probably right about "any" being a bit misleading, but I think this is doing the right thing. Fixed LUT entries (nonexistent at the moment) should not be affected by the aging process. Reviewed-by: Alvin Šipraga <alsi@bang-olufsen.dk> > ChangeLog v1->v2: > - New patch suggested by Vladimir. > --- > drivers/net/dsa/rtl8366rb.c | 14 ++++++++++++++ > 1 file changed, 14 insertions(+) > > diff --git a/drivers/net/dsa/rtl8366rb.c b/drivers/net/dsa/rtl8366rb.c > index 4cb0e336ce6b..548282119cc4 100644 > --- a/drivers/net/dsa/rtl8366rb.c > +++ b/drivers/net/dsa/rtl8366rb.c > @@ -1219,6 +1219,19 @@ rtl8366rb_port_bridge_flags(struct dsa_switch *ds, int port, > return 0; > } > > +static void > +rtl8366rb_port_fast_age(struct dsa_switch *ds, int port) > +{ > + struct realtek_smi *smi = ds->priv; > + > + /* This will age out any L2 entries */ > + regmap_update_bits(smi->map, RTL8366RB_SECURITY_CTRL, > + BIT(port), BIT(port)); > + /* Restore the normal state of things */ > + regmap_update_bits(smi->map, RTL8366RB_SECURITY_CTRL, > + BIT(port), 0); > +} > + > static int > rtl8366rb_port_bridge_join(struct dsa_switch *ds, int port, > struct net_device *bridge) > @@ -1673,6 +1686,7 @@ static const struct dsa_switch_ops rtl8366rb_switch_ops = { > .port_disable = rtl8366rb_port_disable, > .port_pre_bridge_flags = rtl8366rb_port_pre_bridge_flags, > .port_bridge_flags = rtl8366rb_port_bridge_flags, > + .port_fast_age = rtl8366rb_port_fast_age, > .port_change_mtu = rtl8366rb_change_mtu, > .port_max_mtu = rtl8366rb_max_mtu, > }; >
On Tue, Aug 31, 2021 at 12:46 AM Vladimir Oltean <olteanv@gmail.com> wrote: > > + /* This will age out any L2 entries */ > > Clarify "any L2 entries". The fdb flushing process should remove the > dynamically learned FDB entries, it should keep the static ones. Did you > say "any" because rtl8366rb does not implement static FDB entries via > .port_fdb_add, and therefore all entries are dynamic, or does it really > delete static FDB entries? It's what Realtek calls "L2 entries" sadly I do not fully understand their lingo. The ASIC can do static L2 entries as well, but I haven't looked into that. The (confused) docs for the function that set these bits is the following: "ASIC will age out L2 entry with fields Static, Auth and IP_MULT are 0. Aging out function is for new address learning LUT update because size of LUT is limited, old address information should not be kept and get more new learning SA information. Age field of L2 LUT is updated by following sequence {0b10,0b11,0b01,0b00} which means the LUT entries with age value 0b00 is free for ASIC. ASIC will use this aging sequence to decide which entry to be replace by new SA learning information. This function can be replace by setting STP state each port." Next it sets the bit for the port in register RTL8366RB_SECURITY_CTRL. Realtek talks about "LUT" which I think is the same as "FDB" (which I assume is forwarding database, I'm not good with this stuff). My interpretation of this convoluted text is that static, auth and ip_mult will *not* be affected ("are 0"), but only learned entries in the LUT/FDB will be affected. The sequence listed in the comment I interpret as a reference to what the ASIC is doing with the age field for the entry internally to achieve this. Then I guess they say that one can also do fast aging by stopping the port (duh). I'll update the doc to say "any learned L2 entries", but eager to hear what you say about it too :) Yours, Linus Walleij
On Tue, Sep 07, 2021 at 07:48:43PM +0200, Linus Walleij wrote: > On Tue, Aug 31, 2021 at 12:46 AM Vladimir Oltean <olteanv@gmail.com> wrote: > > > > + /* This will age out any L2 entries */ > > > > Clarify "any L2 entries". The fdb flushing process should remove the > > dynamically learned FDB entries, it should keep the static ones. Did you > > say "any" because rtl8366rb does not implement static FDB entries via > > .port_fdb_add, and therefore all entries are dynamic, or does it really > > delete static FDB entries? > > It's what Realtek calls "L2 entries" sadly I do not fully understand > their lingo. > > The ASIC can do static L2 entries as well, but I haven't looked into > that. The (confused) docs for the function that set these bits is > the following: > > "ASIC will age out L2 entry with fields Static, Auth and IP_MULT are 0. > Aging out function is for new address learning LUT update because > size of LUT is limited, old address information should not be kept and > get more new learning SA information. Age field of L2 LUT is updated > by following sequence {0b10,0b11,0b01,0b00} which means the LUT This is {3, 2, 1, 0} in 2-bit Gray code, really curious why they went for that coding scheme. It is common to designate the states of an FSM in Gray code because of the single bit change required on state transitions, but in this case, every ageing state should have a transition path back to 3 when a packet with that {MAC DA, VLAN ID} is received on the port, and the L2 entry is refreshed. The Gray code is a micro-optimization that doesn't seem to help for the primary state transition there. Anyway, doesn't make a difference. > entries with age value 0b00 is free for ASIC. ASIC will use this aging > sequence to decide which entry to be replace by new SA learning > information. This function can be replace by setting STP state each > port." > > Next it sets the bit for the port in register > RTL8366RB_SECURITY_CTRL. > > Realtek talks about "LUT" which I think is the same as "FDB" > (which I assume is forwarding database, I'm not good with this stuff). LUT is "look-up table", any piece of memory which translates between a key and a value is a look-up table. In this case, the forwarding database would qualify as a look-up table where the key is the {MAC DA, VLAN ID} tuple, and the value is the destination port mask. > My interpretation of this convoluted text is that static, auth and ip_mult > will *not* be affected ("are 0"), but only learned entries in the LUT/FDB > will be affected. Same interpretation here. This behavior is to be expected. > The sequence listed in the comment I interpret as a reference to what > the ASIC is doing with the age field for the entry internally to > achieve this. Then I guess they say that one can also do fast aging by > stopping the port (duh). > > I'll update the doc to say "any learned L2 entries", but eager to hear > what you say about it too :) Your interpretation seems correct (I can't think of anything else being meant), but I don't know why you say "duh" about the update of STP state resulting in the port losing its dynamic L2 entries. Sure, it makes sense, but many other vendors do not do that automatically, and DSA calls .port_fast_age whenever the STP state transitions from a value capable of learning (LEARNING, FORWARDING) to one incapable of learning (DISABLED, BLOCKING, LISTENING). To prove/disprove, it would be interesting to implement port STP states, without implementing .port_fast_age, force a port down and then back up, and then run "bridge fdb" and see whether it is true that STP state changes also lead to FDB flushing but at a hardware level (whether there is any 'self' entry being reported). By this logic, the hardware should also auto-age its dynamically learned L2 entries when address learning is turned off, and there would be no purpose at all in implementing the .port_fast_age method. Also curious if that is the case.
On Wed, Sep 8, 2021 at 10:10 PM Vladimir Oltean <olteanv@gmail.com> wrote: > Your interpretation seems correct (I can't think of anything else being meant), > but I don't know why you say "duh" about the update of STP state > resulting in the port losing its dynamic L2 entries. Sure, it makes > sense, but many other vendors do not do that automatically, and DSA > calls .port_fast_age whenever the STP state transitions from a value > capable of learning (LEARNING, FORWARDING) to one incapable of learning > (DISABLED, BLOCKING, LISTENING). > > To prove/disprove, it would be interesting to implement port STP states, > without implementing .port_fast_age, force a port down and then back up, > and then run "bridge fdb" and see whether it is true that STP state > changes also lead to FDB flushing but at a hardware level (whether there > is any 'self' entry being reported). I have been looking into this. What makes RTL8366RB so confusing is a compulsive use of FIDs. For example Linux DSA has: ds->ops->port_stp_state_set(ds, port, state); This is pretty straight forward. The vendor RTL8366RB API however has this: int32 rtl8368s_setAsicSpanningTreeStatus(enum PORTID port, enum FIDVALUE fid, enum SPTSTATE state) So this is set per FID instead of per VID. I also looked into proper FDB support and there is the same problem. For example I want to implement: static int rtl8366rb_port_fdb_add(struct dsa_switch *ds, int port, const unsigned char *addr, u16 vid) But the FDB static (also autolearn) entries has this format: struct l2tb_macstatic_st{ ether_addr_t mac; uint16 fid:3; uint16 reserved1:13; uint16 mbr:8; uint16 reserved2:4; uint16 block:1; uint16 auth:1; uint16 swst:1; uint16 ipmulti:1; uint16 reserved3; }; (swst indicates a static entry ipmulti a multicast entry, mbr is apparently for S-VLAN, which I'm not familiar with.) So again using a FID rather than port or VID in the database. I am starting to wonder whether I should just associate 1-1 the FID:s with the 6 ports (0..5) to simplify things. Or one FID per defined VID until they run out, as atleast OpenWRT connects VLAN1 to all ports on a bridge. Yours, Linus Walleij
On Fri, Sep 10, 2021 at 03:59:18PM +0200, Linus Walleij wrote: > On Wed, Sep 8, 2021 at 10:10 PM Vladimir Oltean <olteanv@gmail.com> wrote: > > > Your interpretation seems correct (I can't think of anything else being meant), > > but I don't know why you say "duh" about the update of STP state > > resulting in the port losing its dynamic L2 entries. Sure, it makes > > sense, but many other vendors do not do that automatically, and DSA > > calls .port_fast_age whenever the STP state transitions from a value > > capable of learning (LEARNING, FORWARDING) to one incapable of learning > > (DISABLED, BLOCKING, LISTENING). > > > > To prove/disprove, it would be interesting to implement port STP states, > > without implementing .port_fast_age, force a port down and then back up, > > and then run "bridge fdb" and see whether it is true that STP state > > changes also lead to FDB flushing but at a hardware level (whether there > > is any 'self' entry being reported). > > I have been looking into this. > > What makes RTL8366RB so confusing is a compulsive use of FIDs. It's not confusing, it's great, and I'm glad that you're around and willing to spend some time so we can discuss this. > For example Linux DSA has: > > ds->ops->port_stp_state_set(ds, port, state); > > This is pretty straight forward. The vendor RTL8366RB API however has this: > > int32 rtl8368s_setAsicSpanningTreeStatus(enum PORTID port, enum > FIDVALUE fid, enum SPTSTATE state) > > So this is set per FID instead of per VID. It's per {port,FID} actually. It is useful in case you want to support MSTP (STP per VLAN, your port is BLOCKING in one VLAN but FORWARDING in another) > I also looked into proper FDB support and there is the same problem. > For example I want to implement: > > static int rtl8366rb_port_fdb_add(struct dsa_switch *ds, int port, > const unsigned char *addr, u16 vid) > > But the FDB static (also autolearn) entries has this format: > > struct l2tb_macstatic_st{ > ether_addr_t mac; > uint16 fid:3; > uint16 reserved1:13; > uint16 mbr:8; > uint16 reserved2:4; > uint16 block:1; > uint16 auth:1; > uint16 swst:1; > uint16 ipmulti:1; > uint16 reserved3; > }; > > (swst indicates a static entry ipmulti a multicast entry, mbr is apparently > for S-VLAN, which I'm not familiar with.) > > So again using a FID rather than port or VID in the database. > > I am starting to wonder whether I should just associate 1-1 the FID:s > with the 6 ports (0..5) to simplify things. Or one FID per defined VID > until they run out, as atleast OpenWRT connects VLAN1 to all ports on > a bridge. No, don't rush it/hack it. A FID is basically the domain in which your L2 lookup table will find a destination MAC address. When every port has a unique FID and they are under the same bridge, one port will never be able to find an L2 lookup table entry learned on another port, because that other port has learned it in another FID. That's not what you want. On the other hand, when a port is standalone, you very much want packets received from that port to go _only_ towards the CPU [ via flooding ], and have no temptation at all to even try to forward that packet towards another switch port. So standalone ports should not have the same FID as ports that are in a bridge. As for bridges, what FID to use? Well, in the case of a VLAN-unaware bridge, you can configure all ports of that bridge to use the same FID. So the FDB lookup will find entries learned on ports that are members of the same bridge, but not entries learned on ports that are members of other bridges. In the case of a VLAN-aware bridge, you have two choices. You can do the same thing as in the case of VLAN-unaware bridges, and this will turn your switch into an 802.1Q bridge with Shared VLAN Learning (SVL). This means that a packet will effectively be forwarded only based on MAC DA, the VLAN ID will be ignored when performing the FDB lookup (because the FDB lookup in your hw is actually per FID, and we made a 1:1 association between the FID and the _bridge_, not the _bridge_VLAN_). So you can never have two stations with the same MAC address in different VLANs, that would confuse your hardware. The second approach is to associate every {bridge, VLAN} pair with a different hardware FID. This will turn your switch into an 802.1Q Independent VLAN Learning (IVL) bridge, so you can have multiple stations attached to the same bridge, having the same MAC address, but they are in different VLANs, so your hardware will keep separate FDB entries for them and they will not overlap (if your bridge was SVL, there would be a single FDB entry for both stations, and it would bounce from one port to another). So in both cases, VLAN 1 of bridge br0 maps to a different FID compared to VLAN 1 of bridge br1. That is the point. The difference is that: - with SVL, VLAN 1, 2, 3, 4 .... of br0 all map to the same FID. - with IVL, VLAN 1, 2, 3, 4 ... of br0 map to different FIDs. The obvious limitation to the second approach is the number of VLANs you can support, it is limited by the number of hardware FIDs. In your switch, that seems to be 8, so not a lot. So IMO, I would go for a SVL approach. What I would do is start with these patches: https://patchwork.kernel.org/project/netdevbpf/cover/20210818120150.892647-1-vladimir.oltean@nxp.com/ I will resubmit them (actually slightly modified variants) during the first weeks of the next kernel development cycle. Check out what changes in the .port_fdb_add function prototype, and see how you can map that new "bridge_num" argument to a FID. Also check out how other drivers make use of FIDs (search for FID_STANDALONE and FID_BRIDGED in the mt7530 driver). That driver only performs FDB isolation between standalone ports and bridged ports, but not between one bridge and another. So the FIDs are underutilized.
diff --git a/drivers/net/dsa/rtl8366rb.c b/drivers/net/dsa/rtl8366rb.c index 4cb0e336ce6b..548282119cc4 100644 --- a/drivers/net/dsa/rtl8366rb.c +++ b/drivers/net/dsa/rtl8366rb.c @@ -1219,6 +1219,19 @@ rtl8366rb_port_bridge_flags(struct dsa_switch *ds, int port, return 0; } +static void +rtl8366rb_port_fast_age(struct dsa_switch *ds, int port) +{ + struct realtek_smi *smi = ds->priv; + + /* This will age out any L2 entries */ + regmap_update_bits(smi->map, RTL8366RB_SECURITY_CTRL, + BIT(port), BIT(port)); + /* Restore the normal state of things */ + regmap_update_bits(smi->map, RTL8366RB_SECURITY_CTRL, + BIT(port), 0); +} + static int rtl8366rb_port_bridge_join(struct dsa_switch *ds, int port, struct net_device *bridge) @@ -1673,6 +1686,7 @@ static const struct dsa_switch_ops rtl8366rb_switch_ops = { .port_disable = rtl8366rb_port_disable, .port_pre_bridge_flags = rtl8366rb_port_pre_bridge_flags, .port_bridge_flags = rtl8366rb_port_bridge_flags, + .port_fast_age = rtl8366rb_port_fast_age, .port_change_mtu = rtl8366rb_change_mtu, .port_max_mtu = rtl8366rb_max_mtu, };
This implements fast aging per-port using the special "security" register, which will flush any L2 LUTs on a port. Suggested-by: Vladimir Oltean <olteanv@gmail.com> Cc: Alvin Šipraga <alsi@bang-olufsen.dk> Cc: Mauri Sandberg <sandberg@mailfence.com> Cc: DENG Qingfang <dqfext@gmail.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org> --- ChangeLog v1->v2: - New patch suggested by Vladimir. --- drivers/net/dsa/rtl8366rb.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) -- 2.31.1