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([2a01:e0a:e17:9700:16d2:7456:6634:9626]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-22c3ee1a78dsm18489415ad.253.2025.04.17.05.24.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 17 Apr 2025 05:24:51 -0700 (PDT) From: =?utf-8?b?Q2zDqW1lbnQgTMOpZ2Vy?= To: Paul Walmsley , Palmer Dabbelt , Anup Patel , Atish Patra , Shuah Khan , Jonathan Corbet , linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, kvm@vger.kernel.org, kvm-riscv@lists.infradead.org, linux-kselftest@vger.kernel.org Cc: =?utf-8?b?Q2zDqW1lbnQgTMOpZ2Vy?= , Samuel Holland , Andrew Jones Subject: [PATCH v5 06/13] riscv: misaligned: use on_each_cpu() for scalar misaligned access probing Date: Thu, 17 Apr 2025 14:19:53 +0200 Message-ID: <20250417122337.547969-7-cleger@rivosinc.com> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250417122337.547969-1-cleger@rivosinc.com> References: <20250417122337.547969-1-cleger@rivosinc.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 schedule_on_each_cpu() was used without any good reason while documented as very slow. This call was in the boot path, so better use on_each_cpu() for scalar misaligned checking. Vector misaligned check still needs to use schedule_on_each_cpu() since it requires irqs to be enabled but that's less of a problem since this code is ran in a kthread. Add a comment to explicit that. Signed-off-by: Clément Léger Reviewed-by: Andrew Jones --- arch/riscv/kernel/traps_misaligned.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/riscv/kernel/traps_misaligned.c b/arch/riscv/kernel/traps_misaligned.c index 058a69c30181..fbac0cf1fd30 100644 --- a/arch/riscv/kernel/traps_misaligned.c +++ b/arch/riscv/kernel/traps_misaligned.c @@ -610,6 +610,10 @@ bool __init check_vector_unaligned_access_emulated_all_cpus(void) { int cpu; + /* + * While being documented as very slow, schedule_on_each_cpu() is used since + * kernel_vector_begin() expects irqs to be enabled or it will panic() + */ schedule_on_each_cpu(check_vector_unaligned_access_emulated); for_each_online_cpu(cpu) @@ -630,7 +634,7 @@ bool __init check_vector_unaligned_access_emulated_all_cpus(void) static bool unaligned_ctl __read_mostly; -static void check_unaligned_access_emulated(struct work_struct *work __always_unused) +static void check_unaligned_access_emulated(void *arg __always_unused) { int cpu = smp_processor_id(); long *mas_ptr = per_cpu_ptr(&misaligned_access_speed, cpu); @@ -671,7 +675,7 @@ bool __init check_unaligned_access_emulated_all_cpus(void) * accesses emulated since tasks requesting such control can run on any * CPU. */ - schedule_on_each_cpu(check_unaligned_access_emulated); + on_each_cpu(check_unaligned_access_emulated, NULL, 1); for_each_online_cpu(cpu) if (per_cpu(misaligned_access_speed, cpu)