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charset="UTF-8" Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 5/11/20, Paul Durrant wrote: >> -----Original Message----- >> From: Denis Kirjanov >> Sent: 11 May 2020 13:12 >> To: paul@xen.org >> Cc: netdev@vger.kernel.org; brouer@redhat.com; jgross@suse.com; >> wei.liu@kernel.org; >> ilias.apalodimas@linaro.org >> Subject: Re: [PATCH net-next v9 2/2] xen networking: add XDP offset >> adjustment to xen-netback >> >> On 5/11/20, Paul Durrant wrote: >> >> -----Original Message----- >> >> From: Denis Kirjanov >> >> Sent: 11 May 2020 11:22 >> >> To: netdev@vger.kernel.org >> >> Cc: brouer@redhat.com; jgross@suse.com; wei.liu@kernel.org; >> >> paul@xen.org; >> >> ilias.apalodimas@linaro.org >> >> Subject: [PATCH net-next v9 2/2] xen networking: add XDP offset >> >> adjustment >> >> to xen-netback >> >> >> >> the patch basically adds the offset adjustment and netfront >> >> state reading to make XDP work on netfront side. >> >> >> >> Signed-off-by: Denis Kirjanov >> >> --- >> >> drivers/net/xen-netback/common.h | 2 ++ >> >> drivers/net/xen-netback/netback.c | 7 +++++++ >> >> drivers/net/xen-netback/rx.c | 7 ++++++- >> >> drivers/net/xen-netback/xenbus.c | 28 ++++++++++++++++++++++++++++ >> >> 4 files changed, 43 insertions(+), 1 deletion(-) >> >> >> >> diff --git a/drivers/net/xen-netback/common.h >> >> b/drivers/net/xen-netback/common.h >> >> index 05847eb..4a148d6 100644 >> >> --- a/drivers/net/xen-netback/common.h >> >> +++ b/drivers/net/xen-netback/common.h >> >> @@ -280,6 +280,7 @@ struct xenvif { >> >> u8 ip_csum:1; >> >> u8 ipv6_csum:1; >> >> u8 multicast_control:1; >> >> + u8 xdp_enabled:1; >> >> >> >> /* Is this interface disabled? True when backend discovers >> >> * frontend is rogue. >> >> @@ -395,6 +396,7 @@ static inline pending_ring_idx_t >> >> nr_pending_reqs(struct xenvif_queue *queue) >> >> irqreturn_t xenvif_interrupt(int irq, void *dev_id); >> >> >> >> extern bool separate_tx_rx_irq; >> >> +extern bool provides_xdp_headroom; >> >> >> >> extern unsigned int rx_drain_timeout_msecs; >> >> extern unsigned int rx_stall_timeout_msecs; >> >> diff --git a/drivers/net/xen-netback/netback.c >> >> b/drivers/net/xen-netback/netback.c >> >> index 315dfc6..6dfca72 100644 >> >> --- a/drivers/net/xen-netback/netback.c >> >> +++ b/drivers/net/xen-netback/netback.c >> >> @@ -96,6 +96,13 @@ >> >> module_param_named(hash_cache_size, xenvif_hash_cache_size, uint, >> >> 0644); >> >> MODULE_PARM_DESC(hash_cache_size, "Number of flows in the hash >> >> cache"); >> >> >> >> +/* The module parameter tells that we have to put data >> >> + * for xen-netfront with the XDP_PACKET_HEADROOM offset >> >> + * needed for XDP processing >> >> + */ >> >> +bool provides_xdp_headroom = true; >> >> +module_param(provides_xdp_headroom, bool, 0644); >> >> + >> >> static void xenvif_idx_release(struct xenvif_queue *queue, u16 >> >> pending_idx, >> >> u8 status); >> >> >> >> diff --git a/drivers/net/xen-netback/rx.c >> >> b/drivers/net/xen-netback/rx.c >> >> index ef58870..c97c98e 100644 >> >> --- a/drivers/net/xen-netback/rx.c >> >> +++ b/drivers/net/xen-netback/rx.c >> >> @@ -33,6 +33,11 @@ >> >> #include >> >> #include >> >> >> >> +static int xenvif_rx_xdp_offset(struct xenvif *vif) >> >> +{ >> >> + return vif->xdp_enabled ? XDP_PACKET_HEADROOM : 0; >> >> +} >> >> + >> >> static bool xenvif_rx_ring_slots_available(struct xenvif_queue >> >> *queue) >> >> { >> >> RING_IDX prod, cons; >> >> @@ -356,7 +361,7 @@ static void xenvif_rx_data_slot(struct >> >> xenvif_queue >> >> *queue, >> >> struct xen_netif_rx_request *req, >> >> struct xen_netif_rx_response *rsp) >> >> { >> >> - unsigned int offset = 0; >> >> + unsigned int offset = xenvif_rx_xdp_offset(queue->vif); >> >> unsigned int flags; >> >> >> >> do { >> >> diff --git a/drivers/net/xen-netback/xenbus.c >> >> b/drivers/net/xen-netback/xenbus.c >> >> index 286054b..d447191 100644 >> >> --- a/drivers/net/xen-netback/xenbus.c >> >> +++ b/drivers/net/xen-netback/xenbus.c >> >> @@ -393,6 +393,20 @@ static void set_backend_state(struct backend_info >> >> *be, >> >> } >> >> } >> >> >> >> +static void read_xenbus_frontend_xdp(struct backend_info *be, >> >> + struct xenbus_device *dev) >> >> +{ >> >> + struct xenvif *vif = be->vif; >> >> + unsigned int val; >> >> + int err; >> >> + >> >> + err = xenbus_scanf(XBT_NIL, dev->otherend, >> >> + "feature-xdp", "%u", &val); >> >> + if (err != 1) >> >> + return; >> >> + vif->xdp_enabled = val; >> >> +} >> >> + >> >> /** >> >> * Callback received when the frontend's state changes. >> >> */ >> >> @@ -417,6 +431,11 @@ static void frontend_changed(struct xenbus_device >> >> *dev, >> >> set_backend_state(be, XenbusStateConnected); >> >> break; >> >> >> >> + case XenbusStateReconfiguring: >> >> + read_xenbus_frontend_xdp(be, dev); >> > >> > I think this being the only call to read_xenbus_frontend_xdp() is still >> > a >> > problem. What happens if netback is reloaded against a >> > netfront that has already enabled 'feature-xdp'? AFAICT >> > vif->xdp_enabled >> > would remain false after the reload. >> >> in this case xennect_connect() should call talk_to_netback() >> and the function will restore the state from info->netfront_xdp_enabled >> > > No. You're assuming the frontend is aware the backend has been reloaded. It > is not. Hi Paul, I've tried to unbind/bind the device and I can see that the variable is set properly: with enabled XDP: <7>[ 622.177935] xen_netback:backend_switch_state: backend/vif/2/0 -> InitWait <7>[ 622.179917] xen_netback:frontend_changed: /local/domain/2/device/vif/0 -> Connected <6>[ 622.187393] vif vif-2-0 vif2.0: Guest Rx ready <7>[ 622.188451] xen_netback:backend_switch_state: backend/vif/2/0 -> Connected localhost:/sys/bus/xen-backend/drivers/vif # xenstore-ls | grep xdp feature-xdp-headroom = "1" feature-xdp = "1" and with disabled: 7>[ 758.216792] xen_netback:frontend_changed: /local/domain/2/device/vif/0 -> Reconfiguring <7>[ 758.218741] xen_netback:frontend_changed: /local/domain/2/device/vif/0 -> Connected <7>[ 784.177247] xen_netback:backend_switch_state: backend/vif/2/0 -> InitWait <7>[ 784.180101] xen_netback:frontend_changed: /local/domain/2/device/vif/0 -> Connected <6>[ 784.187927] vif vif-2-0 vif2.0: Guest Rx ready <7>[ 784.188890] xen_netback:backend_switch_state: backend/vif/2/0 -> Connected localhost:/sys/bus/xen-backend/drivers/vif # xenstore-ls | grep xdp feature-xdp-headroom = "1" feature-xdp = "0" > > Paul > > >