From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A72D02D73A6; Sat, 17 Oct 2026 15:57:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792252678; cv=none; b=m8jNYNQiI4M/fhj4d9Nr/tSnqUqaDqZWPzNqyAcH087CY5VDnVzYEdL3gEiUvDTiUpJvPT4I5rdie+fwGS3cU30hEpIJjdSQ/hh2ufC7t+H/VWI0P7gWnxsDTkNvy8v+Mpu8+BPLBPNx9QTa8rFl2j1lKTqritB2+0GaNf4OQKg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792252678; c=relaxed/simple; bh=4y/MsNGHl2ccdInqFBzzCdcTDhjUkyXmdiCoj92rvZI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=XP69zpCKtOIC4cJk2cgIZcLUJStprk8piuJ03/98t+ku/m3UdyuKSEyLBTW7faBbDjzbzeu1TCnsgZamy3Y3ePN79BzaFo97v/yXhTMi8IoZ1PZX2/QeXnPKiP/8oNCQONtRIO1/IN74+KOBVmjt8I1ycmol5CRaWZbXWly1vww= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=uXlIHHZa; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="uXlIHHZa" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AAF7C1F000C4; Sat, 17 Oct 2026 15:57:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1792252677; bh=ELEXlsRqGvzWF3bvlDjZA6l5LpaYSiS9qEMp2dxxa4U=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=uXlIHHZau//yYDrF05/7xePTJ9wFlBVC7v6axXWoAGAIj0e/+xt/1RgLUjTefHNz7 S/NREaN9miWqMur3lIsBV+E8DFGX+dUoK0o4VzXkh/NXGsGsxgszZPZd6i2ulz+Al0 K+r4paJIAQ4IKVJRMfQyiMo2LAY6UNmarX/qKS90= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Peter Wang , Stanley Jhu , Bart Van Assche , "Martin K. Petersen (Oracle)" , Sasha Levin Subject: [PATCH 6.18 27/52] scsi: ufs: core: Avoid unsafe MMIO reads in ufshcd_mcq_compl_all_cqes_lock() Date: Sat, 17 Oct 2026 17:54:28 +0200 Message-ID: <20261017155105.731166750@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261017155104.830766652@linuxfoundation.org> References: <20261017155104.830766652@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Stanley Jhu [ Upstream commit 375f3a5691dd46b5d05b90a8968872ec8b2248c5 ] During MCQ host reset, ufshcd_host_reset_and_restore() stops the host controller via ufshcd_hba_stop() (HCE = 0) before calling ufshcd_complete_requests(hba, true) -> ufshcd_mcq_compl_pending_transfer(hba, true) -> ufshcd_mcq_force_compl_one() -> ufshcd_mcq_compl_all_cqes_lock(). Because ufshcd_mcq_force_compl_one() is its sole caller, ufshcd_mcq_compl_all_cqes_lock() always runs with HCE = 0. Despite the comment above ufshcd_mcq_compl_all_cqes_lock() stating that reading CQTPy may not be safe with the controller disabled, the function still calls ufshcd_mcq_update_cq_tail_slot() at the end of its sweep: 1. Unsafe CQTPy MMIO read: Calling ufshcd_mcq_update_cq_tail_slot() at the end of the sweep reads CQTPy over MMIO while HCE = 0, directly contradicting the function's documented contract (commit 1373df88d535 ("scsi: ufs: core: Add a comment block above ufshcd_mcq_compl_all_cqes_lock()")) that reading CQTPy may not be safe with the controller disabled. 2. Spurious error logs on empty slots: Sweeping all max_entries slots visits empty entries where command_desc_base_addr is 0, causing ufshcd_mcq_process_cqe() to log unguarded dev_err(hba->dev, "Abnormal CQ entry!\n") messages. Fix both issues in ufshcd_mcq_compl_all_cqes_lock(): - Remove the ufshcd_mcq_update_cq_tail_slot() call and the redundant hwq->cq_head_slot = hwq->cq_tail_slot assignment without replacement. The two indices are already equal after the sweep: they are equal when the sweep starts, since ufshcd_mcq_poll_cqe_lock() consumes entries until cq_head_slot reaches cq_tail_slot, and the sweep advances cq_head_slot by exactly one full ring. Both indices are also reinitialized before the queue is reused. - Extract ufshcd_mcq_compl_cqe() and invoke it only on non-empty slots during full-ring sweeps, keeping "Abnormal CQ entry!" logging strictly for unexpected empty entries in ufshcd_mcq_poll_cqe_lock(). Fixes: ab248643d3d6 ("scsi: ufs: core: Add error handling for MCQ mode") Cc: stable@vger.kernel.org Reviewed-by: Peter Wang Signed-off-by: Stanley Jhu Reviewed-by: Bart Van Assche Link: https://patch.msgid.link/20260928035816.1294326-2-stanleyjhu@google.com Signed-off-by: Martin K. Petersen (Oracle) Signed-off-by: Sasha Levin --- drivers/ufs/core/ufs-mcq.c | 30 +++++++++++++++++------------- 1 file changed, 17 insertions(+), 13 deletions(-) diff --git a/drivers/ufs/core/ufs-mcq.c b/drivers/ufs/core/ufs-mcq.c index 51e3c65ba94b1..55a7647685b44 100644 --- a/drivers/ufs/core/ufs-mcq.c +++ b/drivers/ufs/core/ufs-mcq.c @@ -303,20 +303,24 @@ static int ufshcd_mcq_get_tag(struct ufs_hba *hba, struct cq_entry *cqe) return div_u64(addr, ufshcd_get_ucd_size(hba)); } +static void ufshcd_mcq_compl_cqe(struct ufs_hba *hba, struct cq_entry *cqe) +{ + int tag = ufshcd_mcq_get_tag(hba, cqe); + + ufshcd_compl_one_cqe(hba, tag, cqe); + /* After processing the CQE, mark it as an empty (invalid) entry. */ + cqe->command_desc_base_addr = 0; +} + static void ufshcd_mcq_process_cqe(struct ufs_hba *hba, struct ufs_hw_queue *hwq) { struct cq_entry *cqe = ufshcd_mcq_cur_cqe(hwq); - if (cqe->command_desc_base_addr) { - int tag = ufshcd_mcq_get_tag(hba, cqe); - - ufshcd_compl_one_cqe(hba, tag, cqe); - /* After processed the cqe, mark it empty (invalid) entry */ - cqe->command_desc_base_addr = 0; - } else { + if (cqe->command_desc_base_addr) + ufshcd_mcq_compl_cqe(hba, cqe); + else dev_err(hba->dev, "Abnormal CQ entry!\n"); - } } /* @@ -324,7 +328,7 @@ static void ufshcd_mcq_process_cqe(struct ufs_hba *hba, * controller disabled (HCE = 0). Reading host controller registers, e.g. the * CQ tail pointer (CQTPy), may not be safe with the host controller disabled. * Hence, iterate over all completion queue entries. This won't result in - * double completions because ufshcd_mcq_process_cqe() clears a CQE after it + * double completions because ufshcd_mcq_compl_cqe() clears a CQE after it * has been processed. */ void ufshcd_mcq_compl_all_cqes_lock(struct ufs_hba *hba, @@ -335,13 +339,13 @@ void ufshcd_mcq_compl_all_cqes_lock(struct ufs_hba *hba, spin_lock_irqsave(&hwq->cq_lock, flags); while (entries > 0) { - ufshcd_mcq_process_cqe(hba, hwq); + struct cq_entry *cqe = ufshcd_mcq_cur_cqe(hwq); + + if (cqe->command_desc_base_addr) + ufshcd_mcq_compl_cqe(hba, cqe); ufshcd_mcq_inc_cq_head_slot(hwq); entries--; } - - ufshcd_mcq_update_cq_tail_slot(hwq); - hwq->cq_head_slot = hwq->cq_tail_slot; spin_unlock_irqrestore(&hwq->cq_lock, flags); } -- 2.53.0