From patchwork Tue Jul 11 15:37:32 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Heiko Stuebner X-Patchwork-Id: 701668 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 58409EB64DC for ; Tue, 11 Jul 2023 15:39:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233014AbjGKPjS (ORCPT ); Tue, 11 Jul 2023 11:39:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51234 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233032AbjGKPjA (ORCPT ); Tue, 11 Jul 2023 11:39:00 -0400 Received: from gloria.sntech.de (gloria.sntech.de [185.11.138.130]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4A7B410E5; Tue, 11 Jul 2023 08:38:02 -0700 (PDT) Received: from i53875a50.versanet.de ([83.135.90.80] 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 1qJFQx-0000g0-8A; Tue, 11 Jul 2023 17:37:47 +0200 From: Heiko Stuebner To: palmer@dabbelt.com, paul.walmsley@sifive.com Cc: aou@eecs.berkeley.edu, heiko@sntech.de, herbert@gondor.apana.org.au, davem@davemloft.net, conor.dooley@microchip.com, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org, christoph.muellner@vrull.eu, ebiggers@kernel.org, Greentime Hu , Vincent Chen , Heiko Stuebner Subject: [PATCH v4 01/12] riscv: Add support for kernel mode vector Date: Tue, 11 Jul 2023 17:37:32 +0200 Message-Id: <20230711153743.1970625-2-heiko@sntech.de> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230711153743.1970625-1-heiko@sntech.de> References: <20230711153743.1970625-1-heiko@sntech.de> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.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 | 17 ++++ arch/riscv/kernel/Makefile | 1 + arch/riscv/kernel/kernel_mode_vector.c | 132 +++++++++++++++++++++++++ 3 files changed, 150 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 3d78930cab51..ac2c23045eec 100644 --- a/arch/riscv/include/asm/vector.h +++ b/arch/riscv/include/asm/vector.h @@ -196,6 +196,23 @@ static inline void __switch_to_vector(struct task_struct *prev, void riscv_v_vstate_ctrl_init(struct task_struct *tsk); bool riscv_v_vstate_ctrl_user_allowed(void); +static inline void riscv_v_flush_cpu_state(void) +{ + asm volatile ( + ".option push\n\t" + ".option arch, +v\n\t" + "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" + ".option pop\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 506cc4a9a45a..3f4435746af7 100644 --- a/arch/riscv/kernel/Makefile +++ b/arch/riscv/kernel/Makefile @@ -61,6 +61,7 @@ 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..2d704190c054 --- /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 */ + riscv_v_vstate_save(current, task_pt_regs(current)); + + /* Enable vector */ + riscv_v_enable(); + + /* Invalidate vector regs */ + riscv_v_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 */ + riscv_v_flush_cpu_state(); + + /* Restore vector state, if any */ + riscv_v_vstate_restore(current, task_pt_regs(current)); + + /* disable vector */ + riscv_v_disable(); + + /* release kernel mode vector */ + put_cpu_vector_context(); +} +EXPORT_SYMBOL_GPL(kernel_rvv_end);