From patchwork Tue Feb 28 00:05:29 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Heiko Stuebner X-Patchwork-Id: 13154319 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id C76CDC7EE32 for ; Tue, 28 Feb 2023 00:06:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=OkLfn9M2fopg5cOhPaFlUTi59955vfmES1SZNADypzU=; b=JMm/QM8teuNrnW vPF0bvq6r8GhLK8boY2jG17L047gNXoMeBdhvlkPH/Dltw2VqY6LOGjs1qabgXdCWuigfFQgMkhVN 75m88WBg1Ps+ks46K5H5Md2/4dA+9OT9/DmTU1nZs7GqcQGpSEnGRIXLp+nTLLECeJztTkEV7Fxa3 Q4lmlEMrHqjRIs/JfBx/t1NB/wS0b8UbwXRyZU92mT/9du28L9c17qk/p2fQawnMDo+K+TYljvuEX 9GRV3NUJFlBxyjbs9xfkkv2kmy9bHsLQaw+HR5HPOns1TMLZyArr85EO8QP3ON4icOhNbvWAinlLa kTzeRNX8gHOcEqJDjvOQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1pWnVQ-00BbqM-2g; Tue, 28 Feb 2023 00:06:08 +0000 Received: from gloria.sntech.de ([185.11.138.130]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1pWnVJ-00Bblc-Im for linux-riscv@lists.infradead.org; Tue, 28 Feb 2023 00:06:04 +0000 Received: from ip5b412258.dynamic.kabel-deutschland.de ([91.65.34.88] helo=phil.lan) by gloria.sntech.de with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1pWnV7-000552-Mh; Tue, 28 Feb 2023 01:05:49 +0100 From: Heiko Stuebner To: palmer@rivosinc.com Cc: greentime.hu@sifive.com, conor@kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, christoph.muellner@vrull.eu, heiko@sntech.de, Vincent Chen , Heiko Stuebner Subject: [PATCH RFC v2 01/16] riscv: Add support for kernel mode vector Date: Tue, 28 Feb 2023 01:05:29 +0100 Message-Id: <20230228000544.2234136-2-heiko@sntech.de> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230228000544.2234136-1-heiko@sntech.de> References: <20230228000544.2234136-1-heiko@sntech.de> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230227_160601_671195_8A6D43FB X-CRM114-Status: GOOD ( 20.40 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org From: Greentime Hu Add kernel_rvv_begin() and kernel_rvv_end() function declarations and corresponding definitions in kernel_mode_vector.c These are needed to wrap uses of vector in kernel mode. Co-developed-by: Vincent Chen Signed-off-by: Vincent Chen Signed-off-by: Greentime Hu Signed-off-by: Heiko Stuebner --- arch/riscv/include/asm/vector.h | 14 +++ arch/riscv/kernel/Makefile | 1 + arch/riscv/kernel/kernel_mode_vector.c | 132 +++++++++++++++++++++++++ 3 files changed, 147 insertions(+) create mode 100644 arch/riscv/kernel/kernel_mode_vector.c diff --git a/arch/riscv/include/asm/vector.h b/arch/riscv/include/asm/vector.h index 7c77696d704a..f38266ec483a 100644 --- a/arch/riscv/include/asm/vector.h +++ b/arch/riscv/include/asm/vector.h @@ -134,6 +134,20 @@ static inline void vstate_restore(struct task_struct *task, } } +static inline void vector_flush_cpu_state(void) +{ + asm volatile ( + "vsetvli t0, x0, e8, m8, ta, ma\n\t" + "vmv.v.i v0, 0\n\t" + "vmv.v.i v8, 0\n\t" + "vmv.v.i v16, 0\n\t" + "vmv.v.i v24, 0\n\t" + : : : "t0"); +} + +void kernel_rvv_begin(void); +void kernel_rvv_end(void); + #else /* ! CONFIG_RISCV_ISA_V */ struct pt_regs; diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile index 48d345a5f326..304c500cc1f7 100644 --- a/arch/riscv/kernel/Makefile +++ b/arch/riscv/kernel/Makefile @@ -56,6 +56,7 @@ obj-$(CONFIG_MMU) += vdso.o vdso/ obj-$(CONFIG_RISCV_M_MODE) += traps_misaligned.o obj-$(CONFIG_FPU) += fpu.o obj-$(CONFIG_RISCV_ISA_V) += vector.o +obj-$(CONFIG_RISCV_ISA_V) += kernel_mode_vector.o obj-$(CONFIG_SMP) += smpboot.o obj-$(CONFIG_SMP) += smp.o obj-$(CONFIG_SMP) += cpu_ops.o diff --git a/arch/riscv/kernel/kernel_mode_vector.c b/arch/riscv/kernel/kernel_mode_vector.c new file mode 100644 index 000000000000..0277168af0c5 --- /dev/null +++ b/arch/riscv/kernel/kernel_mode_vector.c @@ -0,0 +1,132 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (C) 2012 ARM Ltd. + * Author: Catalin Marinas + * Copyright (C) 2017 Linaro Ltd. + * Copyright (C) 2021 SiFive + */ +#include +#include +#include +#include +#include + +#include +#include + +DECLARE_PER_CPU(bool, vector_context_busy); +DEFINE_PER_CPU(bool, vector_context_busy); + +/* + * may_use_vector - whether it is allowable at this time to issue vector + * instructions or access the vector register file + * + * Callers must not assume that the result remains true beyond the next + * preempt_enable() or return from softirq context. + */ +static __must_check inline bool may_use_vector(void) +{ + /* + * vector_context_busy is only set while preemption is disabled, + * and is clear whenever preemption is enabled. Since + * this_cpu_read() is atomic w.r.t. preemption, vector_context_busy + * cannot change under our feet -- if it's set we cannot be + * migrated, and if it's clear we cannot be migrated to a CPU + * where it is set. + */ + return !in_irq() && !irqs_disabled() && !in_nmi() && + !this_cpu_read(vector_context_busy); +} + +/* + * Claim ownership of the CPU vector context for use by the calling context. + * + * The caller may freely manipulate the vector context metadata until + * put_cpu_vector_context() is called. + */ +static void get_cpu_vector_context(void) +{ + bool busy; + + preempt_disable(); + busy = __this_cpu_xchg(vector_context_busy, true); + + WARN_ON(busy); +} + +/* + * Release the CPU vector context. + * + * Must be called from a context in which get_cpu_vector_context() was + * previously called, with no call to put_cpu_vector_context() in the + * meantime. + */ +static void put_cpu_vector_context(void) +{ + bool busy = __this_cpu_xchg(vector_context_busy, false); + + WARN_ON(!busy); + preempt_enable(); +} + +/* + * kernel_rvv_begin(): obtain the CPU vector registers for use by the calling + * context + * + * Must not be called unless may_use_vector() returns true. + * Task context in the vector registers is saved back to memory as necessary. + * + * A matching call to kernel_rvv_end() must be made before returning from the + * calling context. + * + * The caller may freely use the vector registers until kernel_rvv_end() is + * called. + */ +void kernel_rvv_begin(void) +{ + if (WARN_ON(!has_vector())) + return; + + WARN_ON(!may_use_vector()); + + /* Acquire kernel mode vector */ + get_cpu_vector_context(); + + /* Save vector state, if any */ + vstate_save(current, task_pt_regs(current)); + + /* Enable vector */ + rvv_enable(); + + /* Invalidate vector regs */ + vector_flush_cpu_state(); +} +EXPORT_SYMBOL_GPL(kernel_rvv_begin); + +/* + * kernel_rvv_end(): give the CPU vector registers back to the current task + * + * Must be called from a context in which kernel_rvv_begin() was previously + * called, with no call to kernel_rvv_end() in the meantime. + * + * The caller must not use the vector registers after this function is called, + * unless kernel_rvv_begin() is called again in the meantime. + */ +void kernel_rvv_end(void) +{ + if (WARN_ON(!has_vector())) + return; + + /* Invalidate vector regs */ + vector_flush_cpu_state(); + + /* Restore vector state, if any */ + vstate_restore(current, task_pt_regs(current)); + + /* disable vector */ + rvv_disable(); + + /* release kernel mode vector */ + put_cpu_vector_context(); +} +EXPORT_SYMBOL_GPL(kernel_rvv_end);