From patchwork Sat Dec 4 00:20:35 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Atish Patra X-Patchwork-Id: 12656111 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B3280C4332F for ; Sat, 4 Dec 2021 00:21:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1383740AbhLDAYb (ORCPT ); Fri, 3 Dec 2021 19:24:31 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46592 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1383709AbhLDAYU (ORCPT ); Fri, 3 Dec 2021 19:24:20 -0500 Received: from mail-pl1-x633.google.com (mail-pl1-x633.google.com [IPv6:2607:f8b0:4864:20::633]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B3DBBC061751 for ; Fri, 3 Dec 2021 16:20:55 -0800 (PST) Received: by mail-pl1-x633.google.com with SMTP id b13so3203001plg.2 for ; Fri, 03 Dec 2021 16:20:55 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=atishpatra.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=7u6cD3eNj3Nkz8bLxeT8gXWEPzrZ4rsNyC+UwyU7rX8=; b=HtWNX3NIjismwcfV3/6U6eycTiG77Gg/c59ukN5EkaAmDSnfrtXmyyuQ1hXtS08qGt OU0IzlvEOWrW5blZbay633YznjVgLOXlswB6l17YD3XneWQQgbzwFXBRStqaQH1/ZmPM naNSIO6zEJIInS8dDaxkdABynCJE62dzhIUGU= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=7u6cD3eNj3Nkz8bLxeT8gXWEPzrZ4rsNyC+UwyU7rX8=; b=AAdmRdaXf5+WCz93d6/XNT3WrK2Al4jMllG8Ex2vq9D2MMDiFOhMCdrvorI/vnR7tG FCzaeddCSvIxC4xCtkgwt6p+JzVQ5+9RaFuvFIG/j9E7sFBJKT3VsU1sxi9aE7rrfjyt +oES9m8jqjhdZMJ+RxOm5gzYdObxInNKWTTbyAnNeeqKgdnhHNOU23NbHmss9ukSdSCP kR55DdEkrLMbFglcLpC7Pa1ucMcusvF9XUCjJHGLjW/G4Y95zrMy3qKema4v6l7OSfdX TILll0RwL+3BFMlwHsev96c4Mw/pKStpzFZ7PYTxZ/T1x9Zz6mfTu5Uf34tSZHOQjq+G x8Bw== X-Gm-Message-State: AOAM530Q1aD9NYI2rXA6+JEHdodeM3n/RjZYjwDmODkrDisInGb+SbaU BPbXbYakCoQNTuV7J+YJOGK9 X-Google-Smtp-Source: ABdhPJzKp/tA+vtP8sQx/u94F7a3amr0c187EQ3qwQTlVnU49o2PFuDEg8ylYHVWzgY7vyaJcLC54A== X-Received: by 2002:a17:90a:657:: with SMTP id q23mr17992099pje.21.1638577255185; Fri, 03 Dec 2021 16:20:55 -0800 (PST) Received: from fedora.ba.rivosinc.com (99-13-229-45.lightspeed.snjsca.sbcglobal.net. [99.13.229.45]) by smtp.gmail.com with ESMTPSA id r6sm3272402pjg.21.2021.12.03.16.20.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 03 Dec 2021 16:20:54 -0800 (PST) From: Atish Patra To: linux-kernel@vger.kernel.org Cc: Atish Patra , Alexandre Ghiti , Anup Patel , Greentime Hu , Guo Ren , Heinrich Schuchardt , Ingo Molnar , Jisheng Zhang , kvm-riscv@lists.infradead.org, kvm@vger.kernel.org, linux-riscv@lists.infradead.org, Marc Zyngier , Nanyong Sun , Nick Kossifidis , Palmer Dabbelt , Paul Walmsley , Pekka Enberg , Vincent Chen , Vitaly Wool Subject: [RFC 3/6] RISC-V: Use __cpu_up_stack/task_pointer only for spinwait method Date: Fri, 3 Dec 2021 16:20:35 -0800 Message-Id: <20211204002038.113653-4-atishp@atishpatra.org> X-Mailer: git-send-email 2.33.1 In-Reply-To: <20211204002038.113653-1-atishp@atishpatra.org> References: <20211204002038.113653-1-atishp@atishpatra.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org From: Atish Patra The __cpu_up_stack/task_pointer array is only used for spinwait method now. The per cpu array based lookup is also fragile for platforms with discontiguous/sparse hartids. The spinwait method is only used for M-mode Linux or older firmwares without SBI HSM extension. For general Linux systems, ordered booting method is preferred anyways to support cpu hotplug and kexec. Make sure that __cpu_up_stack/task_pointer is only used for spinwait method. Take this opportunity to rename it to __cpu_spinwait_stack/task_pointer to emphasize the purpose as well. Signed-off-by: Atish Patra Reviewed-by: Anup Patel --- arch/riscv/include/asm/cpu_ops.h | 2 -- arch/riscv/kernel/cpu_ops.c | 16 ---------------- arch/riscv/kernel/cpu_ops_spinwait.c | 27 ++++++++++++++++++++++++++- arch/riscv/kernel/head.S | 4 ++-- arch/riscv/kernel/head.h | 4 ++-- 5 files changed, 30 insertions(+), 23 deletions(-) diff --git a/arch/riscv/include/asm/cpu_ops.h b/arch/riscv/include/asm/cpu_ops.h index a8ec3c5c1bd2..134590f1b843 100644 --- a/arch/riscv/include/asm/cpu_ops.h +++ b/arch/riscv/include/asm/cpu_ops.h @@ -40,7 +40,5 @@ struct cpu_operations { extern const struct cpu_operations *cpu_ops[NR_CPUS]; void __init cpu_set_ops(int cpu); -void cpu_update_secondary_bootdata(unsigned int cpuid, - struct task_struct *tidle); #endif /* ifndef __ASM_CPU_OPS_H */ diff --git a/arch/riscv/kernel/cpu_ops.c b/arch/riscv/kernel/cpu_ops.c index 3f5a38b03044..c1e30f403c3b 100644 --- a/arch/riscv/kernel/cpu_ops.c +++ b/arch/riscv/kernel/cpu_ops.c @@ -8,31 +8,15 @@ #include #include #include -#include #include #include #include const struct cpu_operations *cpu_ops[NR_CPUS] __ro_after_init; -void *__cpu_up_stack_pointer[NR_CPUS] __section(".data"); -void *__cpu_up_task_pointer[NR_CPUS] __section(".data"); - extern const struct cpu_operations cpu_ops_sbi; extern const struct cpu_operations cpu_ops_spinwait; -void cpu_update_secondary_bootdata(unsigned int cpuid, - struct task_struct *tidle) -{ - int hartid = cpuid_to_hartid_map(cpuid); - - /* Make sure tidle is updated */ - smp_mb(); - WRITE_ONCE(__cpu_up_stack_pointer[hartid], - task_stack_page(tidle) + THREAD_SIZE); - WRITE_ONCE(__cpu_up_task_pointer[hartid], tidle); -} - void __init cpu_set_ops(int cpuid) { #if IS_ENABLED(CONFIG_RISCV_SBI) diff --git a/arch/riscv/kernel/cpu_ops_spinwait.c b/arch/riscv/kernel/cpu_ops_spinwait.c index b2c957bb68c1..9f398eb94f7a 100644 --- a/arch/riscv/kernel/cpu_ops_spinwait.c +++ b/arch/riscv/kernel/cpu_ops_spinwait.c @@ -6,11 +6,36 @@ #include #include #include +#include #include #include #include const struct cpu_operations cpu_ops_spinwait; +void *__cpu_spinwait_stack_pointer[NR_CPUS] __section(".data"); +void *__cpu_spinwait_task_pointer[NR_CPUS] __section(".data"); + +static void cpu_update_secondary_bootdata(unsigned int cpuid, + struct task_struct *tidle) +{ + int hartid = cpuid_to_hartid_map(cpuid); + + /* + * The hartid must be less than NR_CPUS to avoid out-of-bound access + * errors for __cpu_spinwait_stack/task_pointer. That is not always possible + * for platforms with discontiguous hartid numbering scheme. That's why + * spinwait booting is not the recommended approach for any platforms + * and will be removed in future. + */ + if (hartid == INVALID_HARTID || hartid >= NR_CPUS) + return; + + /* Make sure tidle is updated */ + smp_mb(); + WRITE_ONCE(__cpu_spinwait_stack_pointer[hartid], + task_stack_page(tidle) + THREAD_SIZE); + WRITE_ONCE(__cpu_spinwait_task_pointer[hartid], tidle); +} static int spinwait_cpu_prepare(unsigned int cpuid) { @@ -28,7 +53,7 @@ static int spinwait_cpu_start(unsigned int cpuid, struct task_struct *tidle) * selects the first cpu to boot the kernel and causes the remainder * of the cpus to spin in a loop waiting for their stack pointer to be * setup by that main cpu. Writing to bootdata - * (i.e __cpu_up_stack_pointer) signals to the spinning cpus that they + * (i.e __cpu_spinwait_stack_pointer) signals to the spinning cpus that they * can continue the boot process. */ cpu_update_secondary_bootdata(cpuid, tidle); diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S index 40d4c625513c..6f8e99eac6a1 100644 --- a/arch/riscv/kernel/head.S +++ b/arch/riscv/kernel/head.S @@ -347,9 +347,9 @@ clear_bss_done: csrw CSR_TVEC, a3 slli a3, a0, LGREG - la a1, __cpu_up_stack_pointer + la a1, __cpu_spinwait_stack_pointer XIP_FIXUP_OFFSET a1 - la a2, __cpu_up_task_pointer + la a2, __cpu_spinwait_task_pointer XIP_FIXUP_OFFSET a2 add a1, a3, a1 add a2, a3, a2 diff --git a/arch/riscv/kernel/head.h b/arch/riscv/kernel/head.h index aabbc3ac3e48..5393cca77790 100644 --- a/arch/riscv/kernel/head.h +++ b/arch/riscv/kernel/head.h @@ -16,7 +16,7 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa); asmlinkage void __init __copy_data(void); #endif -extern void *__cpu_up_stack_pointer[]; -extern void *__cpu_up_task_pointer[]; +extern void *__cpu_spinwait_stack_pointer[]; +extern void *__cpu_spinwait_task_pointer[]; #endif /* __ASM_HEAD_H */