From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 6F6DE2003D1 for ; Tue, 12 Nov 2024 14:23:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731421402; cv=none; b=j8Zse9d5FiixYyyB9Hxen4LxgcZ84HemJ56nVlaWPcdqZmEtKks+HRLO4JqRIXU6l4jU7/smxqZmIgU0XG2Zy06nbEbk3/qrEpfXuXKyoxQ7Ye858JNUA/8qQoymFku8RjzJE4H2n24DbzMSdaD5bsD/jWwYq3CgzWAmJNozVoY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731421402; c=relaxed/simple; bh=rrl5Cf3sGFo9Tm43JqFtYQb0O1dldmbe1HOCsSTldCg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=YPppnGTVG94IbbM0yEcZsp6IJKKuIFpEC5pSFNa46wOGAW3bJKisYpZ0vQfWLrEYASuz4DSuM812+fIe+S29Szz+PWwVGDTcSxNv+DMW1dJEOjYrUX3N7wYUi6Efj/rQ5EY32Qur3UB4RxfQZ8Um+MaPhifF7HYJmCDy2xCV1pg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ax+Ywrn1; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ax+Ywrn1" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B004DC4CED0; Tue, 12 Nov 2024 14:23:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1731421402; bh=rrl5Cf3sGFo9Tm43JqFtYQb0O1dldmbe1HOCsSTldCg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ax+Ywrn1Wt/6DkjiZaZMN7opdu7msl9gpeZ79VYbOgLeTO/q3w1JVhW+F66f/A73L dwq+RWTelZfE7RC8W3R55W84IMlbRH5T2Q9Zj8KrMon5/c/xSo5XV/sk/CEI+YHfkg 9PXPxWgjswqeqjyai7v3eSVC51Jo7cpIrbUICOCXTjnnxOtpMFni/lRI4kz/Wwwh83 F7+W8K5nq0rqv9gtgNFjAsUK5lzkSp7VHBb5CoWYWhXGH7SJ1copcnbaN2QSLLROI2 RnwdQVq37WWUBOZ58+NTY7u8z/0SVwxDfVzhy5iijltVtD37KFBMseZIGCMKUdltIj lKPK/jTjmeAaA== From: Frederic Weisbecker To: LKML Cc: Frederic Weisbecker , Catalin Marinas , Will Deacon , Marc Zyngier , Oliver Upton , Ard Biesheuvel , Mark Rutland , Andrew Morton , Peter Zijlstra , Thomas Gleixner Subject: [PATCH 11/21] arm64: Keep first mismatched 32bits el0 capable CPU online through its callbacks Date: Tue, 12 Nov 2024 15:22:35 +0100 Message-ID: <20241112142248.20503-12-frederic@kernel.org> X-Mailer: git-send-email 2.46.0 In-Reply-To: <20241112142248.20503-1-frederic@kernel.org> References: <20241112142248.20503-1-frederic@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The first mismatched 32bits el0 capable CPU is designated as the last resort CPU for compat 32 bits tasks. As such this CPU is forbidden to go offline. However this restriction is applied to the device object of the CPU, which is not easy to revert later if needed because other components may have forbidden the target to be offline and they are not tracked. But the task cpu possible mask is going to be made aware of housekeeping CPUs. In that context, a better 32 bits el0 last resort CPU may be found later on boot. When that happens, the old fallback can be made offlineable again. To make this possible and more flexible, drive the offlineable decision from the cpuhotplug callbacks themselves. Signed-off-by: Frederic Weisbecker --- arch/arm64/kernel/cpufeature.c | 32 ++++++++++++++++++-------------- 1 file changed, 18 insertions(+), 14 deletions(-) diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 718728a85430..53ee8ce38d5b 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -3591,15 +3591,15 @@ void __init setup_user_features(void) minsigstksz_setup(); } -static int enable_mismatched_32bit_el0(unsigned int cpu) -{ - /* - * The first 32-bit-capable CPU we detected and so can no longer - * be offlined by userspace. -1 indicates we haven't yet onlined - * a 32-bit-capable CPU. - */ - static int lucky_winner = -1; +/* + * The first 32-bit-capable CPU we detected and so can no longer + * be offlined by userspace. -1 indicates we haven't yet onlined + * a 32-bit-capable CPU. + */ +static int cpu_32bit_unofflineable = -1; +static int mismatched_32bit_el0_online(unsigned int cpu) +{ struct cpuinfo_arm64 *info = &per_cpu(cpu_data, cpu); bool cpu_32bit = id_aa64pfr0_32bit_el0(info->reg_id_aa64pfr0); @@ -3611,7 +3611,7 @@ static int enable_mismatched_32bit_el0(unsigned int cpu) if (cpumask_test_cpu(0, cpu_32bit_el0_mask) == cpu_32bit) return 0; - if (lucky_winner >= 0) + if (cpu_32bit_unofflineable < 0) return 0; /* @@ -3619,16 +3619,20 @@ static int enable_mismatched_32bit_el0(unsigned int cpu) * 32-bit EL0 online so that is_cpu_allowed() doesn't end up rejecting * every CPU in the system for a 32-bit task. */ - lucky_winner = cpu_32bit ? cpu : cpumask_any_and(cpu_32bit_el0_mask, - cpu_active_mask); - get_cpu_device(lucky_winner)->offline_disabled = true; + cpu_32bit_unofflineable = cpu_32bit ? cpu : cpumask_any_and(cpu_32bit_el0_mask, + cpu_active_mask); setup_elf_hwcaps(compat_elf_hwcaps); elf_hwcap_fixup(); pr_info("Asymmetric 32-bit EL0 support detected on CPU %u; CPU hot-unplug disabled on CPU %u\n", - cpu, lucky_winner); + cpu, cpu_32bit_unofflineable); return 0; } +static int mismatched_32bit_el0_offline(unsigned int cpu) +{ + return cpu == cpu_32bit_unofflineable ? -EBUSY : 0; +} + static int __init init_32bit_el0_mask(void) { if (!allow_mismatched_32bit_el0) @@ -3639,7 +3643,7 @@ static int __init init_32bit_el0_mask(void) return cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "arm64/mismatched_32bit_el0:online", - enable_mismatched_32bit_el0, NULL); + mismatched_32bit_el0_online, mismatched_32bit_el0_offline); } subsys_initcall_sync(init_32bit_el0_mask); -- 2.46.0