From patchwork Thu Jul 13 20:06:04 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Brown X-Patchwork-Id: 13312608 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 73350C001E0 for ; Thu, 13 Jul 2023 20:11:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231962AbjGMULs (ORCPT ); Thu, 13 Jul 2023 16:11:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47238 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230183AbjGMULq (ORCPT ); Thu, 13 Jul 2023 16:11:46 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9BFE330CA; Thu, 13 Jul 2023 13:11:16 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 8D81861B0F; Thu, 13 Jul 2023 20:11:00 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 33903C433C9; Thu, 13 Jul 2023 20:10:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1689279060; bh=o0ANSAw56sA/lMUOCihuB62S6J6BNaztJzZehhETvE0=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=ApDZj1uNZf71FBvouOCrf0wVUKZBSLI6OueVam0HtYW3CKzVHw7ccPspsR6GadW/t 6JKMYvbZIHWgHo+mC5GhpKoZnUrI4yHJ3rChkhiqrI9iAa1A85AO+40S/t0Nc0hw23 lbMkupHw15GIDRin0Ad11BWdAMmbEk+9E7FGUh+t4GaFXUpk4EMsxiVn40T8OEgrdk 4/YA+H/sXL/qhb8A4tY6dqOrfukCEm8vW587MmvQlmg9KeDPmMNnkEXjZ2j5BkwzCn UtqR6LgpSKUpJzDhElGqbr2t3hBPdN4LJ8Rct+OsKdkYdxJ+F8zBeGmaAQJvALZ075 J7TYA1T2d/psQ== From: Mark Brown Date: Thu, 13 Jul 2023 21:06:04 +0100 Subject: [PATCH 1/3] arm64/fpsimd: Ensure SME storage is allocated after SVE VL changes MIME-Version: 1.0 Message-Id: <20230713-arm64-fix-sve-sme-vl-change-v1-1-129dd8611413@kernel.org> References: <20230713-arm64-fix-sve-sme-vl-change-v1-0-129dd8611413@kernel.org> In-Reply-To: <20230713-arm64-fix-sve-sme-vl-change-v1-0-129dd8611413@kernel.org> To: Catalin Marinas , Will Deacon , Shuah Khan Cc: David Spickett , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, Mark Brown , stable@vger.kernel.org X-Mailer: b4 0.13-dev-099c9 X-Developer-Signature: v=1; a=openpgp-sha256; l=3179; i=broonie@kernel.org; h=from:subject:message-id; bh=o0ANSAw56sA/lMUOCihuB62S6J6BNaztJzZehhETvE0=; b=owEBbQGS/pANAwAKASTWi3JdVIfQAcsmYgBksFpNzlGIjJ25VfURcqNr5OdlZ9uZz5Sciz6zF2v/ AgnJnvOJATMEAAEKAB0WIQSt5miqZ1cYtZ/in+ok1otyXVSH0AUCZLBaTQAKCRAk1otyXVSH0GjsB/ 0adS+55bGJsIYkt/TYHWkX71CLRv8+BFzENgFSc3PJTu/3/Z3R2CWVLT9snutH2r4EFffoYq1QdNvb QMUFXoBW1ih7dlCVaxTuZSifF0MNJ+U5Eq+AVO0xIIuKKChEsveQ8mAGCK9D/f+9nuOrnFnEHAkOrh OueZcuR/I8DNofEsSFRU4F7Vv/rEAUi5iYnbvPN32qo5z6CT0QMa1j+5vuMIBoeo47MYa7DnVoOp1A d2LSvG3K+LJ1qOaRCBVISQotHoM5zZS3aaZrqQxZ82+Cg8FiTO8BEek0TlBp+OcGJOBn6Qcclew/2T viSAjxBXH9Y7+48OYQTK8PKfKPh372 X-Developer-Key: i=broonie@kernel.org; a=openpgp; fpr=3F2568AAC26998F9E813A1C5C3F436CA30F5D8EB Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org When we reconfigure the SVE vector length we discard the backing storage for the SVE vectors and then reallocate on next SVE use, leaving the SME specific state alone. This means that we do not enable SME traps if they were already disabled. That means that userspace code can enter streaming mode without trapping, putting the task in a state where if we try to save the state of the task we will fault. Since the ABI does not specify that changing the SVE vector length disturbs SME state, and since SVE code may not be aware of SME code in the process, we shouldn't simply discard any ZA state. Instead immediately reallocate the storage for SVE if SME is active, and disable SME if we change the SVE vector length while there is no SME state active. Disabling SME traps on SVE vector length changes would make the overall code more complex since we would have a state where we have valid SME state stored but might get a SME trap. Fixes: 9e4ab6c89109 ("arm64/sme: Implement vector length configuration prctl()s") Reported-by: David Spickett Signed-off-by: Mark Brown Cc: stable@vger.kernel.org Reported-by: David Spickett Signed-off-by: Mark Brown --- arch/arm64/kernel/fpsimd.c | 32 +++++++++++++++++++++++++------- 1 file changed, 25 insertions(+), 7 deletions(-) diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c index 7a1aeb95d7c3..a527b95c06e7 100644 --- a/arch/arm64/kernel/fpsimd.c +++ b/arch/arm64/kernel/fpsimd.c @@ -847,6 +847,9 @@ void sve_sync_from_fpsimd_zeropad(struct task_struct *task) int vec_set_vector_length(struct task_struct *task, enum vec_type type, unsigned long vl, unsigned long flags) { + bool free_sme = false; + bool alloc_sve = true; + if (flags & ~(unsigned long)(PR_SVE_VL_INHERIT | PR_SVE_SET_VL_ONEXEC)) return -EINVAL; @@ -897,22 +900,37 @@ int vec_set_vector_length(struct task_struct *task, enum vec_type type, task->thread.fp_type = FP_STATE_FPSIMD; } - if (system_supports_sme() && type == ARM64_VEC_SME) { - task->thread.svcr &= ~(SVCR_SM_MASK | - SVCR_ZA_MASK); - clear_thread_flag(TIF_SME); + if (system_supports_sme()) { + if (type == ARM64_VEC_SME || + !(task->thread.svcr & (SVCR_SM_MASK | SVCR_ZA_MASK))) { + /* + * We are changing the SME VL or weren't using + * SME anyway, discard the state and force a + * reallocation. + */ + task->thread.svcr &= ~(SVCR_SM_MASK | + SVCR_ZA_MASK); + clear_thread_flag(TIF_SME); + free_sme = true; + } else { + alloc_sve = true; + } } if (task == current) put_cpu_fpsimd_context(); /* - * Force reallocation of task SVE and SME state to the correct - * size on next use: + * Free the changed states if they are not in use, they will + * be reallocated to the correct size on next use. If we need + * SVE state due to having untouched SME state then reallocate + * it immediately. */ sve_free(task); - if (system_supports_sme() && type == ARM64_VEC_SME) + if (free_sme) sme_free(task); + if (alloc_sve) + sve_alloc(task, true); task_set_vl(task, type, vl);