From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-180.mta0.migadu.com (out-180.mta0.migadu.com [91.218.175.180]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D6A8F17F4F6 for ; Wed, 27 Aug 2025 16:45:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.180 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756313128; cv=none; b=nRyFudQojPXrq6fgOSz5lu6w/4m/4FmMDQL3AoNIKwSTP4fAyMDALx+T3OTthzKyZtRJqmSWpOlRnFLbOCY5QGvnt4ro8VqJRjwyTf8U+vogvQQM1XkjHUf4m+hRb2Ja7YFIjQBcffBLgDKOhrN+ydSS0fPt4YlgshgdqDEJ3gk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756313128; c=relaxed/simple; bh=+GazPPqFc6RrIIXrvA8BNxzf8qh2Xf6JDrZLYOYpwhQ=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=p7aaTK0+V5r+w9KHpMbx/oYFbmW0OfUsaywxb43L+p4SJRH0x3IhoeFqwQy+QmFmwAh79V1NOB7kV8tJNdRQmiBHL9pVXMcIj6YX0WBCmtq67NEP16QIZL70jNKwZGNByL2LI8DDLyEGJw5DRNcc4KlMAqRCZ7sR5mdYbJfgSi4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=n6j78a2g; arc=none smtp.client-ip=91.218.175.180 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="n6j78a2g" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1756313121; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=2FkRlhiRvGBSiFCUrNDFJt9G0SpZy+QyM11Xpve/gWE=; b=n6j78a2gU/IQfAqRtdCEUpUqfZLL8VLjiMtLb+DiV1rULTbBIs8laiGqwfvXqrlprB7YML bpi3zhhc69JVdK11jmkgwAUeM7fKE5Vnh6DAo+cW1ioA3w9wBNpglB0D1jk1PPOPsvEOij i8EA5MgKuYGYTMtfdzKVOTYMa4gW8G8= From: Leon Hwang To: bpf@vger.kernel.org Cc: ast@kernel.org, andrii@kernel.org, daniel@iogearbox.net, jolsa@kernel.org, yonghong.song@linux.dev, song@kernel.org, eddyz87@gmail.com, dxu@dxuuu.xyz, deso@posteo.net, leon.hwang@linux.dev, kernel-patches-bot@fb.com Subject: [PATCH bpf-next v4 0/7] bpf: Introduce BPF_F_CPU and BPF_F_ALL_CPUS flags for percpu maps Date: Thu, 28 Aug 2025 00:45:02 +0800 Message-ID: <20250827164509.7401-1-leon.hwang@linux.dev> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT This patch set introduces the BPF_F_CPU and BPF_F_ALL_CPUS flags for percpu maps, as the requirement of BPF_F_ALL_CPUS flag for percpu_array maps was discussed in the thread of "[PATCH bpf-next v3 0/4] bpf: Introduce global percpu data"[1]. The goal of BPF_F_ALL_CPUS flag is to reduce data caching overhead in light skeletons by allowing a single value to be reused to update values across all CPUs. This avoids the M:N problem where M cached values are used to update a map on N CPUs kernel. The BPF_F_CPU flag is accompanied by *flags*-embedded cpu info, which specifies the target CPU for the operation: * For lookup operations: the flag field alongside cpu info enable querying a value on the specified CPU. * For update operations: the flag field alongside cpu info enable updating value for specified CPU. Links: [1] https://lore.kernel.org/bpf/20250526162146.24429-1-leon.hwang@linux.dev/ Changes: v3 -> v4: * Address comments from Andrii: * Remove unnecessary map_type check in bpf_map_value_size(). * Reduce code churn. * Remove unnecessary do_delete check in __htab_map_lookup_and_delete_batch(). * Introduce bpf_percpu_copy_to_user() and bpf_percpu_copy_from_user(). * Rename check_map_flags() to bpf_map_check_op_flags() with extra_flags_mask. * Add human-readable pr_warn() explanations in validate_map_op(). * Use flags in bpf_map__delete_elem() and bpf_map__lookup_and_delete_elem(). * Drop "for alignment reasons". v3 link: https://lore.kernel.org/bpf/20250821160817.70285-1-leon.hwang@linux.dev/ v2 -> v3: * Address comments from Alexei: * Use BPF_F_ALL_CPUS instead of BPF_ALL_CPUS magic. * Introduce these two cpu flags for all percpu maps. * Address comments from Jiri: * Reduce some unnecessary u32 cast. * Refactor more generic map flags check function. * A code style issue. v2 link: https://lore.kernel.org/bpf/20250805163017.17015-1-leon.hwang@linux.dev/ v1 -> v2: * Address comments from Andrii: * Embed cpu info as high 32 bits of *flags* totally. * Use ERANGE instead of E2BIG. * Few format issues. RFC v2 -> v1: * Address comments from Andrii: * Use '&=' and '|='. * Replace 'reuse_value' with simpler and less duplication code. * Replace 'ASSERT_FALSE' with two 'ASSERT_OK_PTR's in self test. RFC v1 -> RFC v2: * Address comments from Andrii: * Embed cpu to flags on kernel side. * Change BPF_ALL_CPU macro to BPF_ALL_CPUS enum. * Copy/update element within RCU protection. * Update bpf_map_value_size() including BPF_F_CPU case. * Use zero as default value to get cpu option. * Update documents of APIs to be generic. * Add size_t:0 to opts definitions. * Update validate_map_op() including BPF_F_CPU case. * Use LIBBPF_OPTS instead of DECLARE_LIBBPF_OPTS. Leon Hwang (7): bpf: Introduce internal bpf_map_check_op_flags helper function bpf: Introduce BPF_F_CPU and BPF_F_ALL_CPUS flags bpf: Introduce BPF_F_CPU and BPF_F_ALL_CPUS flags for percpu_array maps bpf: Introduce BPF_F_CPU and BPF_F_ALL_CPUS flags for percpu_hash and lru_percpu_hash maps bpf: Introduce BPF_F_CPU and BPF_F_ALL_CPUS flags for percpu_cgroup_storage maps libbpf: Support BPF_F_CPU and BPF_F_ALL_CPUS flags for percpu maps selftests/bpf: Add cases to test BPF_F_CPU and BPF_F_ALL_CPUS flags include/linux/bpf-cgroup.h | 5 +- include/linux/bpf.h | 126 +++++++++- include/uapi/linux/bpf.h | 2 + kernel/bpf/arraymap.c | 28 +-- kernel/bpf/hashtab.c | 95 +++++--- kernel/bpf/local_storage.c | 42 ++-- kernel/bpf/syscall.c | 64 +++-- tools/include/uapi/linux/bpf.h | 2 + tools/lib/bpf/bpf.h | 8 + tools/lib/bpf/libbpf.c | 33 ++- tools/lib/bpf/libbpf.h | 21 +- .../selftests/bpf/prog_tests/percpu_alloc.c | 224 ++++++++++++++++++ .../selftests/bpf/progs/percpu_alloc_array.c | 32 +++ 13 files changed, 549 insertions(+), 133 deletions(-) -- 2.50.1