From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-14.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2FEBAC433E6 for ; Fri, 28 Aug 2020 18:16:40 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 004C32074A for ; Fri, 28 Aug 2020 18:16:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="KztMVLLR"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="CV4X2xly" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 004C32074A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To:Message-Id:Date: Subject:To:From:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=NmtuJti3aMKOgtVrmEw91pDYB1/xtKa+Npd3AVQfksw=; b=KztMVLLRnRhZXa2BQ5llJ9EA0 JMMRqtiug/cqnnNFpZVQPRkCMK7/9EsyCgV1VHR9o7bLVPyueBILzKUJKbsNbLhV1NKerXAnBcleB 9Ua+6B6KkSxtpMPFZH81u6y05w6bVifFr+Ow1SCi3JpMzDqKwQCSkK6YvI9rgpM7mfffL+UrM8jg7 aLeLwgZTwu7Br89/eWXEOtcHYonQ40S4CKM03MESk/Ro2ns+RKsU79O9wFXaju8XnNi5XHOpE/lVN A06xDm/OY3eyRsfSkDTVpcA5dXHEz9gBhjJYWm/YL10kCGAgrepTCPRdTqhCTgAftZdxRkBXxoX8L 0nf9xsf5w==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kBiuH-0004vb-Vh; Fri, 28 Aug 2020 18:15:22 +0000 Received: from mail.kernel.org ([198.145.29.99]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kBith-0004i6-Od for linux-arm-kernel@lists.infradead.org; Fri, 28 Aug 2020 18:14:47 +0000 Received: from localhost (fw-tnat.cambridge.arm.com [217.140.96.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 8D68920C56; Fri, 28 Aug 2020 18:14:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598638485; bh=T2CyBIAhfPqy4qdZdZkLBjMACP4I2oXjIeOjmBMjTvM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CV4X2xlyVhh/UqT9C6j74EsLmILO3Ciix9pghW3DPZQI8oBG0Qfew2+5PXB1/+1uN zPv+V9+wvcgud5xjs1NVWMagvAVu1J8WzVb9PVR6Niq6V6O0o+ZkirUDimQnnB8+b3 l5CoFVhwqkHoeRFMHlXjgY6+KhsN+wwK5YgGUKpo= From: Mark Brown To: Catalin Marinas , Will Deacon Subject: [PATCH v4 8/8] arm64/sve: Rework SVE trap access to use TIF_SVE_NEEDS_FLUSH Date: Fri, 28 Aug 2020 19:11:55 +0100 Message-Id: <20200828181155.17745-9-broonie@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200828181155.17745-1-broonie@kernel.org> References: <20200828181155.17745-1-broonie@kernel.org> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200828_141446_030747_3D251338 X-CRM114-Status: GOOD ( 22.34 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Julien Grall , Zhang Lei , Julien Grall , Mark Brown , Dave Martin , linux-arm-kernel@lists.infradead.org, Daniel Kiss Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org From: Julien Grall SVE state will be flushed on the first SVE access trap. At the moment, the SVE state will be generated from the FPSIMD state in software and then loaded in memory. It is possible to use the newly introduce flag TIF_SVE_NEEDS_FLUSH to avoid a lot of memory access. If the FPSIMD state is in memory, the SVE state will be loaded on return to userspace from the FPSIMD state. If the FPSIMD state is loaded, then we need to set the vector-length before relying on return to userspace to flush the SVE registers. This is because the vector length is only set when loading from memory. We also need to rebind the task to the CPU so the newly allocated SVE state is used when the task is saved. Signed-off-by: Julien Grall Signed-off-by: Mark Brown --- arch/arm64/include/asm/fpsimd.h | 2 ++ arch/arm64/kernel/entry-fpsimd.S | 5 +++++ arch/arm64/kernel/fpsimd.c | 32 +++++++++++++++++++++----------- 3 files changed, 28 insertions(+), 11 deletions(-) diff --git a/arch/arm64/include/asm/fpsimd.h b/arch/arm64/include/asm/fpsimd.h index bec5f14b622a..e60aa4ebb351 100644 --- a/arch/arm64/include/asm/fpsimd.h +++ b/arch/arm64/include/asm/fpsimd.h @@ -74,6 +74,8 @@ extern void sve_load_from_fpsimd_state(struct user_fpsimd_state const *state, unsigned long vq_minus_1); extern unsigned int sve_get_vl(void); +extern void sve_set_vq(unsigned long vq_minus_1); + struct arm64_cpu_capabilities; extern void sve_kernel_enable(const struct arm64_cpu_capabilities *__unused); diff --git a/arch/arm64/kernel/entry-fpsimd.S b/arch/arm64/kernel/entry-fpsimd.S index 2ca395c25448..3ecec60d3295 100644 --- a/arch/arm64/kernel/entry-fpsimd.S +++ b/arch/arm64/kernel/entry-fpsimd.S @@ -48,6 +48,11 @@ SYM_FUNC_START(sve_get_vl) ret SYM_FUNC_END(sve_get_vl) +SYM_FUNC_START(sve_set_vq) + sve_load_vq x0, x1, x2 + ret +SYM_FUNC_END(sve_set_vq) + /* * Load SVE state from FPSIMD state. * diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c index b0fc8823d731..af721e48d658 100644 --- a/arch/arm64/kernel/fpsimd.c +++ b/arch/arm64/kernel/fpsimd.c @@ -953,10 +953,10 @@ void fpsimd_release_task(struct task_struct *dead_task) /* * Trapped SVE access * - * Storage is allocated for the full SVE state, the current FPSIMD - * register contents are migrated across, and TIF_SVE is set so that - * the SVE access trap will be disabled the next time this task - * reaches ret_to_user. + * Storage is allocated for the full SVE state so that the code + * running subsequently has somewhere to save the SVE registers to. We + * then rely on ret_to_user to actually convert the FPSIMD registers + * to SVE state by flushing as required. * * TIF_SVE should be clear on entry: otherwise, fpsimd_restore_current_state() * would have disabled the SVE access trap for userspace during @@ -974,14 +974,24 @@ void do_sve_acc(unsigned int esr, struct pt_regs *regs) get_cpu_fpsimd_context(); - fpsimd_save(); - - /* Force ret_to_user to reload the registers: */ - fpsimd_flush_task_state(current); + set_thread_flag(TIF_SVE_NEEDS_FLUSH); + /* + * We should not be here with SVE enabled. TIF_SVE will be set + * before returning to userspace by fpsimd_restore_current_state(). + */ + WARN_ON(test_thread_flag(TIF_SVE)); - fpsimd_to_sve(current); - if (test_and_set_thread_flag(TIF_SVE)) - WARN_ON(1); /* SVE access shouldn't have trapped */ + /* + * When the FPSIMD state is loaded: + * - The return path (see fpsimd_restore_current_state) requires + * the vector length to be loaded beforehand. + * - We need to rebind the task to the CPU so the newly allocated + * SVE state is used when the task is saved. + */ + if (!test_thread_flag(TIF_FOREIGN_FPSTATE)) { + sve_set_vq(sve_vq_from_vl(current->thread.sve_vl) - 1); + fpsimd_bind_task_to_cpu(); + } put_cpu_fpsimd_context(); } -- 2.20.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel