From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-173.mta0.migadu.com (out-173.mta0.migadu.com [91.218.175.173]) (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 5E663224B05 for ; Thu, 25 Sep 2025 15:38:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.173 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758814702; cv=none; b=raai2TtL3cWLCvJL1t2Sn0sSnCyUp1DDmqz2WhFsPYffVOomjaHWBCSVoGpFSRXxo9G0tK01GtbEK2HvNZkzUJm4QCb26be6uYLH27C/obIOwWKd9CYypEt4NsjZt4booFGDaQeUZfARS5BSRx0eDbxm1lbhRWZ7nZ0zUHrLv5U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758814702; c=relaxed/simple; bh=+FF1ryzKweVsdOSWCJFa+2+Bn7qzAnxqJPElYzCC9I8=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=XVoZvYRLRRaxdKVv90eG9PbGPDI5bIWYcY2kMTrBtfz8yC9JcHbSnkNwQ95pFX+pNXc6azycJlsVBAG9yxYAJ9c7ungiaKdxr5hZs7rwZZ0oXjmHodmhHaCWa7WLnL4wXeEWTzEZMwI8ck5VjRJYhCyWGlKQ3e9KAX6Qv+O0CnE= 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=lqnVh8JG; arc=none smtp.client-ip=91.218.175.173 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="lqnVh8JG" 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=1758814696; 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=eOJ8UE71iw1U0sBvg8Ur+znz2rDvC+2n17rjfVXFV2k=; b=lqnVh8JGP70LUzbMHHOIBmEr0cYSS0HxMH/aYLP6b2CkQPIN9MeysLuknZfaQjFtIvFK8r i5LkYJ13vhpySpLxORx9794k8oeHjJ5QEEs3qhH6I3d+ASVWNCh4pwtXqq9ZcK/eEIQQXZ KxIhpB5Cq5AzPthoY+dpEQPV1hA31HU= 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 v8 0/7] bpf: Introduce BPF_F_CPU and BPF_F_ALL_CPUS flags for percpu maps Date: Thu, 25 Sep 2025 23:37:39 +0800 Message-ID: <20250925153746.96154-1-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: v7 -> v8: * Address comments from Andrii: * Check BPF_F_LOCK when update percpu_array, percpu_hash and lru_percpu_hash maps. * Refactor flags check in __htab_map_lookup_and_delete_batch(). * Keep value_size unaligned and copy value using copy_map_value() in __htab_map_lookup_and_delete_batch() when BPF_F_CPU is specified. * Update warn message in libbpf's validate_map_op(). * Update comment of libbpf's bpf_map__lookup_elem(). v6 -> v7: * Get correct value size for percpu_hash and lru_percpu_hash in update_batch API. * Set 'count' as 'max_entries' in test cases for lookup_batch API. * Address comment from Alexei: * Move cpu flags check into bpf_map_check_op_flags(). v5 -> v6: * Move bpf_map_check_op_flags() from 'bpf.h' to 'syscall.c'. * Address comments from Alexei: * Drop the refactoring code of data copying logic for percpu maps. * Drop bpf_map_check_op_flags() wrappers. v4 -> v5: * Address comments from Andrii: * Refactor data copying logic for all percpu maps. * Drop this_cpu_ptr() micro-optimization. * Drop cpu check in libbpf's validate_map_op(). * Enhance bpf_map_check_op_flags() using *allowed flags* instead of 'extra_flags_mask'. 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. 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: Add BPF_F_CPU and BPF_F_ALL_CPUS flags support for percpu_array maps bpf: Add BPF_F_CPU and BPF_F_ALL_CPUS flags support for percpu_hash and lru_percpu_hash maps bpf: Add BPF_F_CPU and BPF_F_ALL_CPUS flags support for percpu_cgroup_storage maps libbpf: Add BPF_F_CPU and BPF_F_ALL_CPUS flags support for percpu maps selftests/bpf: Add cases to test BPF_F_CPU and BPF_F_ALL_CPUS flags include/linux/bpf-cgroup.h | 4 +- include/linux/bpf.h | 44 +++- include/uapi/linux/bpf.h | 2 + kernel/bpf/arraymap.c | 24 +- kernel/bpf/hashtab.c | 79 ++++-- kernel/bpf/local_storage.c | 22 +- kernel/bpf/syscall.c | 65 +++-- tools/include/uapi/linux/bpf.h | 2 + tools/lib/bpf/bpf.h | 8 + tools/lib/bpf/libbpf.c | 26 +- tools/lib/bpf/libbpf.h | 21 +- .../selftests/bpf/prog_tests/percpu_alloc.c | 234 ++++++++++++++++++ .../selftests/bpf/progs/percpu_alloc_array.c | 32 +++ 13 files changed, 473 insertions(+), 90 deletions(-) -- 2.50.1