From patchwork Wed Aug 15 10:23:01 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Leizhen \(ThunderTown\)" X-Patchwork-Id: 144276 Delivered-To: patch@linaro.org Received: by 2002:a2e:9754:0:0:0:0:0 with SMTP id f20-v6csp655480ljj; Wed, 15 Aug 2018 03:23:37 -0700 (PDT) X-Google-Smtp-Source: AA+uWPwbmD2WFfT5LLj+DdeclPNPQupYeXDiB+cn4BosvvmQJiVCtL6UiE+mcx24fTupkCQdF5KO X-Received: by 2002:a17:902:6b05:: with SMTP id o5-v6mr23616467plk.338.1534328617558; Wed, 15 Aug 2018 03:23:37 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1534328617; cv=none; d=google.com; s=arc-20160816; b=eYpZ6O1XFJ94xdtzmSBVrsRdSoZbiwQQoMJTiWdgt7DVeqjD7qpo+OOBmEnW419hHH hvV3NXg7F/xLTgvJwGyh/98E4L3eLjQt/cbxBMYNcIlmy2A5RboCx8tnVR6ETnUiFPIN cpxvuVOkF40MhJHwt2wkW/P6AviTixUuHM91vdwP7ISM5gyEDh7dX67i1fDjxxwI6x38 F6ByeX41N/2NH7hXzblYgULz2n5FGYMD7QW2pvyojE6IlK/aExCk4Rra9EOST9u5i0JX 8hYnVvUgZ4nRLJerwZ7uhVdool0fXDkpFbXJsK9VhP3zHn/Xqpn5bIGosXYwm/3qJwiU kdbQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:arc-authentication-results; bh=nbEwdIp62yKPIo9mGXCby6qf5S5zNk9NDcay98Wt7E0=; b=HnNMaHo859eapMBocpq+TGzcihJ4WePavYnK5qylwxFvssgZPplye+nOOV6bnBgQja ZK9am8T2gUfK23ze12hG8i0umPp//WpalrKPZKBbyr4pveU2zAUf8VLKWDWhqF3Ne8xa PzXDVy6MrttZHf0ycAXlwNwIKrztfc1Dqc+Q1npVwgyUDNU+pMi4NuKpbbevICcTV3x+ hoyFnV0E5Jr6ik28bwjLCXDlC23n2tYXyMF+T1OCctukKy1YCWxwB2O9kVwmCpbteB8L u6TanjJjvp7HtDokJlKx/biJ29i4dTm+CORVRPd2oZQZGfg9ZwrjvgBVaRqPnF4hbc5d o0WA== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id u4-v6si23006315pgm.454.2018.08.15.03.23.36; Wed, 15 Aug 2018 03:23:37 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729106AbeHONPH (ORCPT + 32 others); Wed, 15 Aug 2018 09:15:07 -0400 Received: from szxga06-in.huawei.com ([45.249.212.32]:60846 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728910AbeHONPH (ORCPT ); Wed, 15 Aug 2018 09:15:07 -0400 Received: from DGGEMS401-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id C726950DC2D5E; Wed, 15 Aug 2018 18:23:28 +0800 (CST) Received: from localhost (10.177.23.164) by DGGEMS401-HUB.china.huawei.com (10.3.19.201) with Microsoft SMTP Server id 14.3.399.0; Wed, 15 Aug 2018 18:23:23 +0800 From: Zhen Lei To: Robin Murphy , Will Deacon , Joerg Roedel , linux-arm-kernel , iommu , linux-kernel CC: Zhen Lei , LinuxArm , Hanjun Guo , Libin , "John Garry" Subject: [PATCH v3 1/2] iommu/arm-smmu-v3: fix unexpected CMD_SYNC timeout Date: Wed, 15 Aug 2018 18:23:01 +0800 Message-ID: <1534328582-17664-2-git-send-email-thunder.leizhen@huawei.com> X-Mailer: git-send-email 1.9.5.msysgit.0 In-Reply-To: <1534328582-17664-1-git-send-email-thunder.leizhen@huawei.com> References: <1534328582-17664-1-git-send-email-thunder.leizhen@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.177.23.164] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The condition "(int)(VAL - sync_idx) >= 0" to break loop in function __arm_smmu_sync_poll_msi requires that sync_idx must be increased monotonously according to the sequence of the CMDs in the cmdq. But ".msidata = atomic_inc_return_relaxed(&smmu->sync_nr)" is not protected by spinlock, so the following scenarios may appear: cpu0 cpu1 msidata=0 msidata=1 insert cmd1 insert cmd0 smmu execute cmd1 smmu execute cmd0 poll timeout, because msidata=1 is overridden by cmd0, that means VAL=0, sync_idx=1. This is not a functional problem, just make the caller wait for a long time until TIMEOUT. It's rare to happen, because any other CMD_SYNCs during the waiting period will break it. Signed-off-by: Zhen Lei --- drivers/iommu/arm-smmu-v3.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) -- 1.8.3 diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c index 1d64710..3f5c236 100644 --- a/drivers/iommu/arm-smmu-v3.c +++ b/drivers/iommu/arm-smmu-v3.c @@ -566,7 +566,7 @@ struct arm_smmu_device { int gerr_irq; int combined_irq; - atomic_t sync_nr; + u32 sync_nr; unsigned long ias; /* IPA */ unsigned long oas; /* PA */ @@ -775,6 +775,11 @@ static int queue_remove_raw(struct arm_smmu_queue *q, u64 *ent) return 0; } +static inline void arm_smmu_cmdq_sync_set_msidata(u64 *cmd, u32 msidata) +{ + cmd[0] |= FIELD_PREP(CMDQ_SYNC_0_MSIDATA, msidata); +} + /* High-level queue accessors */ static int arm_smmu_cmdq_build_cmd(u64 *cmd, struct arm_smmu_cmdq_ent *ent) { @@ -836,7 +841,6 @@ static int arm_smmu_cmdq_build_cmd(u64 *cmd, struct arm_smmu_cmdq_ent *ent) cmd[0] |= FIELD_PREP(CMDQ_SYNC_0_CS, CMDQ_SYNC_0_CS_SEV); cmd[0] |= FIELD_PREP(CMDQ_SYNC_0_MSH, ARM_SMMU_SH_ISH); cmd[0] |= FIELD_PREP(CMDQ_SYNC_0_MSIATTR, ARM_SMMU_MEMATTR_OIWB); - cmd[0] |= FIELD_PREP(CMDQ_SYNC_0_MSIDATA, ent->sync.msidata); cmd[1] |= ent->sync.msiaddr & CMDQ_SYNC_1_MSIADDR_MASK; break; default: @@ -947,7 +951,6 @@ static int __arm_smmu_cmdq_issue_sync_msi(struct arm_smmu_device *smmu) struct arm_smmu_cmdq_ent ent = { .opcode = CMDQ_OP_CMD_SYNC, .sync = { - .msidata = atomic_inc_return_relaxed(&smmu->sync_nr), .msiaddr = virt_to_phys(&smmu->sync_count), }, }; @@ -955,6 +958,8 @@ static int __arm_smmu_cmdq_issue_sync_msi(struct arm_smmu_device *smmu) arm_smmu_cmdq_build_cmd(cmd, &ent); spin_lock_irqsave(&smmu->cmdq.lock, flags); + ent.sync.msidata = ++smmu->sync_nr; + arm_smmu_cmdq_sync_set_msidata(cmd, ent.sync.msidata); arm_smmu_cmdq_insert_cmd(smmu, cmd); spin_unlock_irqrestore(&smmu->cmdq.lock, flags); @@ -2179,7 +2184,6 @@ static int arm_smmu_init_structures(struct arm_smmu_device *smmu) { int ret; - atomic_set(&smmu->sync_nr, 0); ret = arm_smmu_init_queues(smmu); if (ret) return ret;