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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 9C53AC3B188 for ; Thu, 13 Feb 2020 04:15:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6A12F218AC for ; Thu, 13 Feb 2020 04:15:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581567354; bh=+YW1FXahCnvnIehudFGs86R/2HZNVmlSwPr6RKKBndY=; h=Subject:To:Cc:From:Date:List-ID:From; b=JXqBV07F6wClP8cc7/DYUn45gkxXoG7KBgR5gi4Ysm63s3mNF3ppT5FMzGPCLDJrF jAaYjuH4Wdsxs1Ab3yTq7iXosXYRVIiCTjx4wIETYp0Sa0AOqMu7nQHKJ3smqMxiFm nkuGxw2Kp+TrAXJb0ihQV1IQjXglWC2aVbQXGlWk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729547AbgBMEPy (ORCPT ); Wed, 12 Feb 2020 23:15:54 -0500 Received: from out2-smtp.messagingengine.com ([66.111.4.26]:48361 "EHLO out2-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729546AbgBMEPx (ORCPT ); Wed, 12 Feb 2020 23:15:53 -0500 Received: from compute6.internal (compute6.nyi.internal [10.202.2.46]) by mailout.nyi.internal (Postfix) with ESMTP id EDA0421F82; Wed, 12 Feb 2020 23:15:52 -0500 (EST) Received: from mailfrontend2 ([10.202.2.163]) by compute6.internal (MEProxy); Wed, 12 Feb 2020 23:15:52 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-transfer-encoding:content-type :date:from:message-id:mime-version:subject:to:x-me-proxy :x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s=fm2; bh=k9synL l9CiEUh2h3zC3SFYUHVjvEdT8Cn2Fd9u7+1u4=; b=Vl7AkwgdErKhFPDAf5ecpI t10LCXApseNh30e9KGQJjtLyOb8gQ7rnmAG+j5AkMJZbrWjoBRzK1g+jG27rn4Pn QDUZGMrfjcn5qhrBporLXoydllNRYGjrit8/H7vRyt3On54OcPCQMhgYGY3aGxkh kPLW4/W59cd00Ozr6nKy5RnL6JpANfssNr9a/m3tpeSAo2d0h9Tg60ZjkjZN/IEZ ZE2MYUBmQjRev7RwvPBq9+/pkJwYpkgciKf7FeNIRMWGIpeSl9ql0q4qaa6ymnFX rtY332BF2d31bUjV/hUBkHo831TTyd+qtjikLuU8dHvmzJWvlCxm+Nep6lMNpOyg == X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedugedrieejgdejudcutefuodetggdotefrodftvf curfhrohhfihhlvgemucfhrghsthforghilhdpqfgfvfdpuffrtefokffrpgfnqfghnecu uegrihhlohhuthemuceftddtnecunecujfgurhepuffvhfffkfggtgfgsehtkeertddttd flnecuhfhrohhmpeeoghhrvghgkhhhsehlihhnuhigfhhouhhnuggrthhiohhnrdhorhhg qeenucfkphepvddtledrfeejrdeljedrudelgeenucevlhhushhtvghrufhiiigvpedtne curfgrrhgrmhepmhgrihhlfhhrohhmpehgrhgvgheskhhrohgrhhdrtghomh X-ME-Proxy: Received: from localhost (unknown [209.37.97.194]) by mail.messagingengine.com (Postfix) with ESMTPA id 977C230600DC; Wed, 12 Feb 2020 23:15:52 -0500 (EST) Subject: FAILED: patch "[PATCH] arm64: nofpsmid: Handle TIF_FOREIGN_FPSTATE flag cleanly" failed to apply to 4.14-stable tree To: suzuki.poulose@arm.com, ardb@kernel.org, catalin.marinas@arm.com, mark.rutland@arm.com, maz@kernel.org, will@kernel.org Cc: From: Date: Wed, 12 Feb 2020 20:15:51 -0800 Message-ID: <158156735133@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch below does not apply to the 4.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 52f73c383b2418f2d31b798e765ae7d596c35021 Mon Sep 17 00:00:00 2001 From: Suzuki K Poulose Date: Mon, 13 Jan 2020 23:30:23 +0000 Subject: [PATCH] arm64: nofpsmid: Handle TIF_FOREIGN_FPSTATE flag cleanly We detect the absence of FP/SIMD after an incapable CPU is brought up, and by then we have kernel threads running already with TIF_FOREIGN_FPSTATE set which could be set for early userspace applications (e.g, modprobe triggered from initramfs) and init. This could cause the applications to loop forever in do_nofity_resume() as we never clear the TIF flag, once we now know that we don't support FP. Fix this by making sure that we clear the TIF_FOREIGN_FPSTATE flag for tasks which may have them set, as we would have done in the normal case, but avoiding touching the hardware state (since we don't support any). Also to make sure we handle the cases seemlessly we categorise the helper functions to two : 1) Helpers for common core code, which calls into take appropriate actions without knowing the current FPSIMD state of the CPU/task. e.g fpsimd_restore_current_state(), fpsimd_flush_task_state(), fpsimd_save_and_flush_cpu_state(). We bail out early for these functions, taking any appropriate actions (e.g, clearing the TIF flag) where necessary to hide the handling from core code. 2) Helpers used when the presence of FP/SIMD is apparent. i.e, save/restore the FP/SIMD register state, modify the CPU/task FP/SIMD state. e.g, fpsimd_save(), task_fpsimd_load() - save/restore task FP/SIMD registers fpsimd_bind_task_to_cpu() \ - Update the "state" metadata for CPU/task. fpsimd_bind_state_to_cpu() / fpsimd_update_current_state() - Update the fp/simd state for the current task from memory. These must not be called in the absence of FP/SIMD. Put in a WARNING to make sure they are not invoked in the absence of FP/SIMD. KVM also uses the TIF_FOREIGN_FPSTATE flag to manage the FP/SIMD state on the CPU. However, without FP/SIMD support we trap all accesses and inject undefined instruction. Thus we should never "load" guest state. Add a sanity check to make sure this is valid. Fixes: 82e0191a1aa11abf ("arm64: Support systems without FP/ASIMD") Cc: Will Deacon Cc: Mark Rutland Reviewed-by: Ard Biesheuvel Reviewed-by: Catalin Marinas Acked-by: Marc Zyngier Signed-off-by: Suzuki K Poulose Signed-off-by: Will Deacon diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c index 3eb338f14386..94289d126993 100644 --- a/arch/arm64/kernel/fpsimd.c +++ b/arch/arm64/kernel/fpsimd.c @@ -269,6 +269,7 @@ static void sve_free(struct task_struct *task) */ static void task_fpsimd_load(void) { + WARN_ON(!system_supports_fpsimd()); WARN_ON(!have_cpu_fpsimd_context()); if (system_supports_sve() && test_thread_flag(TIF_SVE)) @@ -289,6 +290,7 @@ static void fpsimd_save(void) this_cpu_ptr(&fpsimd_last_state); /* set by fpsimd_bind_task_to_cpu() or fpsimd_bind_state_to_cpu() */ + WARN_ON(!system_supports_fpsimd()); WARN_ON(!have_cpu_fpsimd_context()); if (!test_thread_flag(TIF_FOREIGN_FPSTATE)) { @@ -1092,6 +1094,7 @@ void fpsimd_bind_task_to_cpu(void) struct fpsimd_last_state_struct *last = this_cpu_ptr(&fpsimd_last_state); + WARN_ON(!system_supports_fpsimd()); last->st = ¤t->thread.uw.fpsimd_state; last->sve_state = current->thread.sve_state; last->sve_vl = current->thread.sve_vl; @@ -1114,6 +1117,7 @@ void fpsimd_bind_state_to_cpu(struct user_fpsimd_state *st, void *sve_state, struct fpsimd_last_state_struct *last = this_cpu_ptr(&fpsimd_last_state); + WARN_ON(!system_supports_fpsimd()); WARN_ON(!in_softirq() && !irqs_disabled()); last->st = st; @@ -1128,8 +1132,19 @@ void fpsimd_bind_state_to_cpu(struct user_fpsimd_state *st, void *sve_state, */ void fpsimd_restore_current_state(void) { - if (!system_supports_fpsimd()) + /* + * For the tasks that were created before we detected the absence of + * FP/SIMD, the TIF_FOREIGN_FPSTATE could be set via fpsimd_thread_switch(), + * e.g, init. This could be then inherited by the children processes. + * If we later detect that the system doesn't support FP/SIMD, + * we must clear the flag for all the tasks to indicate that the + * FPSTATE is clean (as we can't have one) to avoid looping for ever in + * do_notify_resume(). + */ + if (!system_supports_fpsimd()) { + clear_thread_flag(TIF_FOREIGN_FPSTATE); return; + } get_cpu_fpsimd_context(); @@ -1148,7 +1163,7 @@ void fpsimd_restore_current_state(void) */ void fpsimd_update_current_state(struct user_fpsimd_state const *state) { - if (!system_supports_fpsimd()) + if (WARN_ON(!system_supports_fpsimd())) return; get_cpu_fpsimd_context(); @@ -1179,7 +1194,13 @@ void fpsimd_update_current_state(struct user_fpsimd_state const *state) void fpsimd_flush_task_state(struct task_struct *t) { t->thread.fpsimd_cpu = NR_CPUS; - + /* + * If we don't support fpsimd, bail out after we have + * reset the fpsimd_cpu for this task and clear the + * FPSTATE. + */ + if (!system_supports_fpsimd()) + return; barrier(); set_tsk_thread_flag(t, TIF_FOREIGN_FPSTATE); @@ -1193,6 +1214,7 @@ void fpsimd_flush_task_state(struct task_struct *t) */ static void fpsimd_flush_cpu_state(void) { + WARN_ON(!system_supports_fpsimd()); __this_cpu_write(fpsimd_last_state.st, NULL); set_thread_flag(TIF_FOREIGN_FPSTATE); } @@ -1203,6 +1225,8 @@ static void fpsimd_flush_cpu_state(void) */ void fpsimd_save_and_flush_cpu_state(void) { + if (!system_supports_fpsimd()) + return; WARN_ON(preemptible()); __get_cpu_fpsimd_context(); fpsimd_save(); diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c index 72fbbd86eb5e..e5816d885761 100644 --- a/arch/arm64/kvm/hyp/switch.c +++ b/arch/arm64/kvm/hyp/switch.c @@ -28,7 +28,15 @@ /* Check whether the FP regs were dirtied while in the host-side run loop: */ static bool __hyp_text update_fp_enabled(struct kvm_vcpu *vcpu) { - if (vcpu->arch.host_thread_info->flags & _TIF_FOREIGN_FPSTATE) + /* + * When the system doesn't support FP/SIMD, we cannot rely on + * the _TIF_FOREIGN_FPSTATE flag. However, we always inject an + * abort on the very first access to FP and thus we should never + * see KVM_ARM64_FP_ENABLED. For added safety, make sure we always + * trap the accesses. + */ + if (!system_supports_fpsimd() || + vcpu->arch.host_thread_info->flags & _TIF_FOREIGN_FPSTATE) vcpu->arch.flags &= ~(KVM_ARM64_FP_ENABLED | KVM_ARM64_FP_HOST);