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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 07508CD6E55 for ; Mon, 1 Jun 2026 21:59:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Type:Cc:To:From: Subject:Message-ID:References:Mime-Version:In-Reply-To:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=LWOb+HolO8JcpaQsXLOMu+8Ojdlg6FqfnP4yGw0xQ0I=; b=puFUIsOoX3oUu1l0YUO4vDD0z5 ODYDviOv0RaQ+cE2i/8uGtIEgKKScxPIqELPs1i2yA3pr2Ae/nBvMXwGAhJAAlgKO8Ih9GCygqqmo IN9dd6e+QeI4zVbvdhlZkzoYM8C/j1X8MvKLQmer9HL3dUysU6bwO3YzwtNhRegx/Um6JqdOSNIUx BlqhvAZHf3UXiC02MQO7UT2bcEAapIwUQpFrZG5qfYZBW0L+N6ZSbIRLZo0WSjySSaAHSs8yX9ADh 69TOksH7y6wNoW1qJsYBK8guP6TaFLf6Cy4WDIAi1lrCowe4tQcOZyYOGJLZsCWqmcWTdq3/mMtNj BHkSIbKQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wUAfS-0000000BtPq-3UVw; Mon, 01 Jun 2026 21:59:30 +0000 Received: from mail-pf1-x449.google.com ([2607:f8b0:4864:20::449]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wUAfQ-0000000BtM6-0e0H for linux-arm-kernel@lists.infradead.org; Mon, 01 Jun 2026 21:59:29 +0000 Received: by mail-pf1-x449.google.com with SMTP id d2e1a72fcca58-84238e83851so1369210b3a.1 for ; Mon, 01 Jun 2026 14:59:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1780351167; x=1780955967; darn=lists.infradead.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=LWOb+HolO8JcpaQsXLOMu+8Ojdlg6FqfnP4yGw0xQ0I=; b=HfPg0AQXnRH13h7dswkEt7HtQIsP6k5bQPvj145LsENU/CkE/J+DaYIfeRPUtZQ61M fV9Fwtc/7KHX3V3kOvArGsaM8FbBc6y8jNY8oKsyIxATPqzQt2TjH3poaQeltWqv9WEf 39U7iXjwK/3RH90PmfwFtpm5ewDVHZIMrAw1na5atyCjCaT9PpcjNQ9JlGBamfkVuEuC +hqyX+74Ev0V2vmShki+AiuXX7Ifbu6hzYghHW+mvK8p61miUHvJtlsxQ7uOHWlwc9Ez 4zHrLZ7XyHAw20BAxk1r3MhmOju50QEmCUKgMlIficTnnGhO1XrFq5A8+9BE5ar1gM1o ID1A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1780351167; x=1780955967; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=LWOb+HolO8JcpaQsXLOMu+8Ojdlg6FqfnP4yGw0xQ0I=; b=dDi9Yu5ody1ymy0FsDjLmBHT28mkw2/MQmQQxwt2kIx4anLe2dlCFcG+ioT6HUDZyJ 8gKLGhZFp2ncRkFxgLytMxWhUBm+nKsBFZ5njyXQ7twvcB2a2bhARIneMxnzDpAqYqQB ENwJd2pE33NN5wFZgRR1yywISCfe1/NZYOVRqAUTLPCxp3fSUHGgIfC+E8vC56bRSCIn UsIF39yaFQhjuqB0nJjTCKCwH/I+whZwU0T+kl55g42TZtz+MAubBm/dlbth5eVYVpfx j6zKIMQXR5mE18dzxnUpscCjjhhCoQXQfbVN2EGBsse5wgwrB263fEvgS0BGBUv/a1Im Gtiw== X-Forwarded-Encrypted: i=1; AFNElJ8tb4X0unQm4CZmjmBAER1bNHpz7ApZ7MRnNm7+hDc1NPazXeS71ODUya2uoJtLhmmrSL79/Q7vkaIlRmO4C8yq@lists.infradead.org X-Gm-Message-State: AOJu0Yz69zDwHsV11Z9EqfWo4UCQpcBzTWj/lvNRvkzxz8B1MnTsDmhG 4mb9ijQNzfFjJBWiJrf84IcN8HHUFWX/Pf2Bx4OSGRhhXCS8WncZY6ovgDDrJ7eRtTURd7HhNhn twA== X-Received: from pfaz8.prod.google.com ([2002:aa7:91c8:0:b0:842:4d1f:7750]) (user=praan job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a00:908a:b0:837:e9cc:d46e with SMTP id d2e1a72fcca58-842253ed743mr11621319b3a.21.1780351166606; Mon, 01 Jun 2026 14:59:26 -0700 (PDT) Date: Mon, 1 Jun 2026 21:59:04 +0000 In-Reply-To: <20260601215909.3958732-1-praan@google.com> Mime-Version: 1.0 References: <20260601215909.3958732-1-praan@google.com> X-Mailer: git-send-email 2.54.0.1013.g208068f2d8-goog Message-ID: <20260601215909.3958732-8-praan@google.com> Subject: [PATCH v8 07/12] iommu/arm-smmu-v3: Add CMDQ_PROD_STOP_FLAG to gate CMDQ submissions From: Pranjal Shrivastava To: iommu@lists.linux.dev Cc: Will Deacon , Joerg Roedel , Robin Murphy , Jason Gunthorpe , Mostafa Saleh , Nicolin Chen , Daniel Mentz , Ashish Mhetre , linux-arm-kernel@lists.infradead.org, Pranjal Shrivastava Content-Type: text/plain; charset="UTF-8" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260601_145928_199512_8E3599E7 X-CRM114-Status: GOOD ( 18.09 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Introduce a new bit flag, CMDQ_PROD_STOP_FLAG (bit 30), in the command queue's producer index to safely gate command submissions during device suspension. The flag embeds the suspend state directly into the existing global state The flag checked in the cmpxchg loop in arm_smmu_cmdq_issue_cmdlist(), which acts as a Point of Commitment, ensuring that no indices are reserved or committed once the SMMU begins suspending. This prevents a situation of "abandoned batches" where indices are incremented but commands are never written, which would otherwise lead to timeout during the drain poll. Update queue_inc_prod_n() to preserve this flag during index calculations, ensuring that any in-flight commands that successfully passed the point of commitment can proceed to completion while the flag remains set. Suggested-by: Daniel Mentz Reviewed-by: Nicolin Chen Signed-off-by: Pranjal Shrivastava --- drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 20 +++++++++++++++++++- drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h | 2 ++ 2 files changed, 21 insertions(+), 1 deletion(-) diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c index 6c8631e2f153..c4315bdde7d5 100644 --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c @@ -210,7 +210,8 @@ static int queue_sync_prod_in(struct arm_smmu_queue *q) static u32 queue_inc_prod_n(struct arm_smmu_ll_queue *q, int n) { u32 prod = (Q_WRP(q, q->prod) | Q_IDX(q, q->prod)) + n; - return Q_OVF(q->prod) | Q_WRP(q, prod) | Q_IDX(q, prod); + + return Q_OVF(q->prod) | Q_STOP(q->prod) | Q_WRP(q, prod) | Q_IDX(q, prod); } static void queue_poll_init(struct arm_smmu_device *smmu, @@ -718,8 +719,25 @@ int arm_smmu_cmdq_issue_cmdlist(struct arm_smmu_device *smmu, do { u64 old; + /* + * If the SMMU is suspended/suspending, any new CMDs are elided. + * This loop is the Point of Commitment. If we haven't cmpxchg'd + * our new indices yet, we can safely bail. Once the indices are + * committed, we MUST write valid commands to those slots to + * avoid indefinite polling in the drain function. + */ + if (Q_STOP(llq.prod)) { + local_irq_restore(flags); + return 0; + } + while (!queue_has_space(&llq, n + sync)) { local_irq_restore(flags); + + /* Avoid waiting for space if the SMMU is suspending */ + if (Q_STOP(READ_ONCE(cmdq->q.llq.prod))) + return 0; + if (arm_smmu_cmdq_poll_until_not_full(smmu, cmdq, &llq)) dev_err_ratelimited(smmu->dev, "CMDQ timeout\n"); local_irq_save(flags); diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h index 24d5e28eea88..a3c8417c87d8 100644 --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h @@ -389,6 +389,8 @@ static inline unsigned int arm_smmu_cdtab_l2_idx(unsigned int ssid) #define CMDQ_ERR_CERROR_ATC_INV_IDX 3 #define CMDQ_PROD_OWNED_FLAG Q_OVERFLOW_FLAG +#define CMDQ_PROD_STOP_FLAG (1U << 30) +#define Q_STOP(p) ((p) & CMDQ_PROD_STOP_FLAG) struct arm_smmu_cmd { u64 data[CMDQ_ENT_DWORDS]; -- 2.54.0.1013.g208068f2d8-goog