Add the UAPI and the corresponding kernel part to be able to specify
the frame size which the drivers should start composing metadata
from (if supported).
Instead of having just 1 bit on/off, have the possilibty to set the
threshold for drivers to start composing meta. It helps with the
situations when e.g. lots of traffic receive %XDP_DROP verdict
without looking at the meta. In such cases, the performance on the
small frames (< 96 bytes) can suffer by several Mpps with no
benefits, so setting the threshold of 100-128 makes much sense.
Setting it to 0 or 1 works just like a bitflag, values of 2-14
work like 1, values of SZ_16K+ works like 0.
So, the logics in the drivers should be like:
if (rx_desc->frame_size >= meta_thresh)
compose_meta();
bpf_prog_run_xdp();
The threshold can be set and updated via both BPF link and rtnetlink
(the %IFLA_XDP_META_THRESH attribute) interfaces, got via
&bpf_link_info and is being passed to the drivers inside
&netdev_bpf. net_device_ops::ndo_bpf() is now also being called when
@new_prog == @old_prog && @new_btf_id == @btf_id &&
@new_meta_thresh != @meta_thresh.
Signed-off-by: Alexander Lobakin <alexandr.lobakin@xxxxxxxxx>
---
include/linux/netdevice.h | 2 ++
include/net/xdp.h | 1 +
include/uapi/linux/bpf.h | 10 +++++++-
include/uapi/linux/if_link.h | 1 +
kernel/bpf/syscall.c | 2 +-
net/bpf/core.c | 1 +
net/bpf/dev.c | 38 +++++++++++++++++++++++-------
net/core/rtnetlink.c | 6 +++++
tools/include/uapi/linux/bpf.h | 10 +++++++-
tools/include/uapi/linux/if_link.h | 1 +
10 files changed, 60 insertions(+), 12 deletions(-)
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 2218c1901daf..bc2d82a3d0de 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -985,6 +985,7 @@ struct netdev_bpf {
/* XDP_SETUP_PROG */
struct {
u32 flags;
+ u32 meta_thresh;
u64 btf_id;
struct bpf_prog *prog;
struct netlink_ext_ack *extack;
@@ -3853,6 +3854,7 @@ struct xdp_install_args {
struct net_device *dev;
struct netlink_ext_ack *extack;
u32 flags;
+ u32 meta_thresh;
u64 btf_id;
};
diff --git a/include/net/xdp.h b/include/net/xdp.h
index 13133c7493bc..7b8ba068d28a 100644
--- a/include/net/xdp.h
+++ b/include/net/xdp.h
@@ -401,6 +401,7 @@ static inline bool xdp_metalen_invalid(unsigned long metalen)
struct xdp_attachment_info {
struct bpf_prog *prog;
u64 btf_id;
+ u32 meta_thresh;
u32 flags;
};
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index c67ddb78915d..372170ded1d8 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -1502,6 +1502,10 @@ union bpf_attr {
struct {
/* target metadata BTF + type ID */
__aligned_u64 btf_id;
+ /* frame size to start composing XDP
+ * metadata from
+ */
+ __u32 meta_thresh;
} xdp;
};
} link_create;
@@ -1518,6 +1522,10 @@ union bpf_attr {
struct {
/* new target metadata BTF + type ID */
__aligned_u64 new_btf_id;
+ /* new frame size to start composing XDP
+ * metadata from
+ */
+ __u32 new_meta_thresh;
} xdp;
};
} link_update;
@@ -6148,7 +6156,7 @@ struct bpf_link_info {
} netns;
struct {
__u32 ifindex;
- __u32 :32;
+ __u32 meta_thresh;
__aligned_u64 btf_id;
} xdp;
};
diff --git a/include/uapi/linux/if_link.h b/include/uapi/linux/if_link.h
index 73cdcc86875e..78b448ff1cb7 100644
--- a/include/uapi/linux/if_link.h
+++ b/include/uapi/linux/if_link.h
@@ -1308,6 +1308,7 @@ enum {
IFLA_XDP_HW_PROG_ID,
IFLA_XDP_EXPECTED_FD,
IFLA_XDP_BTF_ID,
+ IFLA_XDP_META_THRESH,
__IFLA_XDP_MAX,
};
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 2e86cfeae10f..e1a56e62bdb4 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -4575,7 +4575,7 @@ static int link_create(union bpf_attr *attr, bpfptr_t uattr)
return ret;
}
-#define BPF_LINK_UPDATE_LAST_FIELD link_update.xdp.new_btf_id
+#define BPF_LINK_UPDATE_LAST_FIELD link_update.xdp.new_meta_thresh
static int link_update(union bpf_attr *attr)
{
diff --git a/net/bpf/core.c b/net/bpf/core.c
index e5abd5a64df7..dcd3b6ae86b7 100644
--- a/net/bpf/core.c
+++ b/net/bpf/core.c
@@ -553,6 +553,7 @@ void xdp_attachment_setup(struct xdp_attachment_info *info,
bpf_prog_put(info->prog);
info->prog = bpf->prog;
info->btf_id = bpf->btf_id;
+ info->meta_thresh = bpf->meta_thresh;
info->flags = bpf->flags;
}
EXPORT_SYMBOL_GPL(xdp_attachment_setup);
diff --git a/net/bpf/dev.c b/net/bpf/dev.c
index e96986220126..82948d0536c8 100644
--- a/net/bpf/dev.c
+++ b/net/bpf/dev.c
@@ -273,6 +273,7 @@ struct bpf_xdp_link {
struct bpf_link link;
struct net_device *dev; /* protected by rtnl_lock, no refcnt held */
int flags;
+ u32 meta_thresh;
u64 btf_id;
};
@@ -358,12 +359,20 @@ static int dev_xdp_install(const struct xdp_install_args *args,
struct netdev_bpf xdp;
int err;
- /* BTF ID must not be set when uninstalling the program */
- if (!prog && args->btf_id)
+ /* Neither BTF ID nor meta threshold can be set when uninstalling
+ * the program
+ */
+ if (!prog && (args->btf_id || args->meta_thresh))
+ return -EINVAL;
+
+ /* Both meta threshold and BTF ID must be either specified or not */
+ if (!args->btf_id != !args->meta_thresh)
return -EINVAL;
memset(&xdp, 0, sizeof(xdp));
xdp.command = mode == XDP_MODE_HW ? XDP_SETUP_PROG_HW : XDP_SETUP_PROG;
+ /* Convert 0 to "infitity" to allow plain >= comparison on hotpath */
+ xdp.meta_thresh = args->meta_thresh ? : ~args->meta_thresh;
xdp.btf_id = args->btf_id;
xdp.extack = args->extack;
xdp.flags = args->flags;
@@ -523,11 +532,13 @@ static int dev_xdp_attach(const struct xdp_install_args *args,
}
}
- /* don't call drivers if the effective program or BTF ID didn't change.
- * If @link == %NULL, we don't know the old value, so the only thing we
- * can do is to call installing unconditionally
+ /* don't call drivers if the effective program or BTF ID / metadata
+ * threshold didn't change. If @link == %NULL, we don't know the
+ * old values, so the only thing we can do is to call installing
+ * unconditionally
*/
- if (new_prog != cur_prog || !link || args->btf_id != link->btf_id) {
+ if (new_prog != cur_prog || !link || args->btf_id != link->btf_id ||
+ args->meta_thresh != link->meta_thresh) {
bpf_op = dev_xdp_bpf_op(dev, mode);
if (!bpf_op) {
NL_SET_ERR_MSG(extack, "Underlying driver does not support XDP in native mode");
@@ -555,6 +566,7 @@ static int dev_xdp_attach_link(struct bpf_xdp_link *link)
.dev = link->dev,
.flags = link->flags,
.btf_id = link->btf_id,
+ .meta_thresh = link->meta_thresh,
};
return dev_xdp_attach(&args, link, NULL, NULL);
@@ -615,16 +627,18 @@ static void bpf_xdp_link_show_fdinfo(const struct bpf_link *link,
struct seq_file *seq)
{
struct bpf_xdp_link *xdp_link = container_of(link, struct bpf_xdp_link, link);
- u32 ifindex = 0;
+ u32 meta_thresh, ifindex = 0;
u64 btf_id;
rtnl_lock();
if (xdp_link->dev)
ifindex = xdp_link->dev->ifindex;
+ meta_thresh = xdp_link->meta_thresh;
btf_id = xdp_link->btf_id;
rtnl_unlock();
seq_printf(seq, "ifindex:\t%u\n", ifindex);
+ seq_printf(seq, "meta_thresh:\t%u\n", meta_thresh);
seq_printf(seq, "btf_id:\t0x%llx\n", btf_id);
}
@@ -632,17 +646,19 @@ static int bpf_xdp_link_fill_link_info(const struct bpf_link *link,
struct bpf_link_info *info)
{
struct bpf_xdp_link *xdp_link = container_of(link, struct bpf_xdp_link, link);
- u32 ifindex = 0;
+ u32 meta_thresh, ifindex = 0;
u64 btf_id;
rtnl_lock();
if (xdp_link->dev)
ifindex = xdp_link->dev->ifindex;
+ meta_thresh = xdp_link->meta_thresh;
btf_id = xdp_link->btf_id;
rtnl_unlock();
info->xdp.ifindex = ifindex;
info->xdp.btf_id = btf_id;
+ info->xdp.meta_thresh = meta_thresh;
return 0;
}
@@ -656,6 +672,7 @@ static int bpf_xdp_link_update(struct bpf_link *link,
.dev = xdp_link->dev,
.flags = xdp_link->flags,
.btf_id = attr->link_update.xdp.new_btf_id,
+ .meta_thresh = attr->link_update.xdp.new_meta_thresh,
};
enum bpf_xdp_mode mode;
bpf_op_t bpf_op;
@@ -680,7 +697,8 @@ static int bpf_xdp_link_update(struct bpf_link *link,
goto out_unlock;
}
- if (old_prog == new_prog && args.btf_id == xdp_link->btf_id) {
+ if (old_prog == new_prog && args.btf_id == xdp_link->btf_id &&
+ args.meta_thresh == xdp_link->meta_thresh) {
/* no-op, don't disturb drivers */
bpf_prog_put(new_prog);
goto out_unlock;
@@ -696,6 +714,7 @@ static int bpf_xdp_link_update(struct bpf_link *link,
bpf_prog_put(old_prog);
xdp_link->btf_id = args.btf_id;
+ xdp_link->meta_thresh = args.meta_thresh;
out_unlock:
rtnl_unlock();
@@ -736,6 +755,7 @@ int bpf_xdp_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
link->dev = dev;
link->flags = attr->link_create.flags;
link->btf_id = attr->link_create.xdp.btf_id;
+ link->meta_thresh = attr->link_create.xdp.meta_thresh;
err = bpf_link_prime(&link->link, &link_primer);
if (err) {
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index a30723b0e50c..500420d5017c 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -1980,6 +1980,7 @@ static const struct nla_policy ifla_xdp_policy[IFLA_XDP_MAX + 1] = {
[IFLA_XDP_FLAGS] = { .type = NLA_U32 },
[IFLA_XDP_PROG_ID] = { .type = NLA_U32 },
[IFLA_XDP_BTF_ID] = { .type = NLA_U64 },
+ [IFLA_XDP_META_THRESH] = { .type = NLA_U32 },
};
static const struct rtnl_link_ops *linkinfo_to_kind_ops(const struct nlattr *nla)
@@ -2962,6 +2963,7 @@ static int do_setlink(const struct sk_buff *skb,
if (tb[IFLA_XDP]) {
struct nlattr *xdp[IFLA_XDP_MAX + 1];
+ u32 meta_thresh = 0;
u32 xdp_flags = 0;
u64 btf_id = 0;
@@ -2991,12 +2993,16 @@ static int do_setlink(const struct sk_buff *skb,
if (xdp[IFLA_XDP_BTF_ID])
btf_id = nla_get_u64(xdp[IFLA_XDP_BTF_ID]);
+ if (xdp[IFLA_XDP_META_THRESH])
+ meta_thresh = nla_get_u32(xdp[IFLA_XDP_META_THRESH]);
+
if (xdp[IFLA_XDP_FD]) {
struct xdp_install_args args = {
.dev = dev,
.extack = extack,
.btf_id = btf_id,
.flags = xdp_flags,
+ .meta_thresh = meta_thresh,
};
int expected_fd = -1;
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index c67ddb78915d..372170ded1d8 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -1502,6 +1502,10 @@ union bpf_attr {
struct {
/* target metadata BTF + type ID */
__aligned_u64 btf_id;
+ /* frame size to start composing XDP
+ * metadata from
+ */
+ __u32 meta_thresh;
} xdp;
};
} link_create;
@@ -1518,6 +1522,10 @@ union bpf_attr {
struct {
/* new target metadata BTF + type ID */
__aligned_u64 new_btf_id;
+ /* new frame size to start composing XDP
+ * metadata from
+ */
+ __u32 new_meta_thresh;
} xdp;
};
} link_update;
@@ -6148,7 +6156,7 @@ struct bpf_link_info {
} netns;
struct {
__u32 ifindex;
- __u32 :32;
+ __u32 meta_thresh;
__aligned_u64 btf_id;
} xdp;
};
diff --git a/tools/include/uapi/linux/if_link.h b/tools/include/uapi/linux/if_link.h
index 68b126678dc8..b73b9c0f06fb 100644
--- a/tools/include/uapi/linux/if_link.h
+++ b/tools/include/uapi/linux/if_link.h
@@ -1213,6 +1213,7 @@ enum {
IFLA_XDP_HW_PROG_ID,
IFLA_XDP_EXPECTED_FD,
IFLA_XDP_BTF_ID,
+ IFLA_XDP_META_THRESH,
__IFLA_XDP_MAX,
};
--
2.36.1
