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Wed, 23 Jul 2025 10:57:19 +0000 (GMT) Received: from nasanex01a.na.qualcomm.com (nasanex01a.na.qualcomm.com [10.52.223.231]) by NASANPPMTA02.qualcomm.com (8.18.1.2/8.18.1.2) with ESMTPS id 56NAvJDL007418 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 23 Jul 2025 10:57:19 GMT Received: from [10.218.49.64] (10.80.80.8) by nasanex01a.na.qualcomm.com (10.52.223.231) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1748.10; Wed, 23 Jul 2025 03:57:16 -0700 Subject: Re: [PATCH v7] usb: misc: qcom_eud: Access EUD_MODE_MANAGER2 through secure calls To: Komal Bajaj , Greg Kroah-Hartman References: <20250722-eud_mode_manager_secure_access-v7-1-40e9a4569895@oss.qualcomm.com> CC: , , , Melody Olvera , Konrad Dybcio From: Souradeep Chowdhury Message-ID: <8ccc4e83-9645-4388-0941-ebeb3ac4d88e@quicinc.com> Date: Wed, 23 Jul 2025 16:26:56 +0530 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.1.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: <20250722-eud_mode_manager_secure_access-v7-1-40e9a4569895@oss.qualcomm.com> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit X-ClientProxiedBy: nasanex01a.na.qualcomm.com (10.52.223.231) To nasanex01a.na.qualcomm.com (10.52.223.231) X-QCInternal: smtphost X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=5800 signatures=585085 X-Authority-Analysis: v=2.4 cv=LdY86ifi c=1 sm=1 tr=0 ts=6880c00f cx=c_pps a=JYp8KDb2vCoCEuGobkYCKw==:117 a=JYp8KDb2vCoCEuGobkYCKw==:17 a=GEpy-HfZoHoA:10 a=IkcTkHD0fZMA:10 a=Wb1JkmetP80A:10 a=VwQbUJbxAAAA:8 a=EUspDBNiAAAA:8 a=COk6AnOGAAAA:8 a=aoTH-x754zP81mJImO0A:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 a=TjNXssC_j7lpFel5tvFf:22 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwNzIzMDA5MiBTYWx0ZWRfX/5xBlZ+jZ1lk U+hRP+H5y7G7Ruxfa3zjMarfU7NyfcK07VIH5GWyjftpOe8xePsYV0qO+Cta1J60UsiyXOSnni5 vWsGPYujaZ9MCZLZ3Zpw/UFHJkJL+em83VK5ltJp9t+qhKUmSEeE+a9UKDO9T3RK7EMCuXUs7f2 yRnLzkm/knYXDCouoOkqSYNc5XPL1nuTL6JO1jQI+zXY0/FcIeRWPjbKwLSbo1hrPKPwTvJl48I MbzmgLH1y6YaLFkPGJd5smHX8RK0SBB9ylfe7R/q9BvtYsCmOqC5uZBzUwmKV9YSgfoT9qNmOA6 w4O6RUDT/wgvMb+YloLgqeCPb6pxtxfAJ44LbusZpHY/p61pFtBkU9CA9UtEGXJNXKcRDt+QWha x6RggoQVGg2WoWQCaGlG84HORBHKYLHFOMloWHmCssp2L2sUDG2fyL9uU5j5X7Oaqa6xpRiP X-Proofpoint-ORIG-GUID: 0rcmqnENa7bSepy5BlpYE6OCd_43fkqk X-Proofpoint-GUID: 0rcmqnENa7bSepy5BlpYE6OCd_43fkqk X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1099,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-07-23_02,2025-07-22_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 mlxscore=0 priorityscore=1501 adultscore=0 phishscore=0 malwarescore=0 lowpriorityscore=0 mlxlogscore=999 bulkscore=0 spamscore=0 suspectscore=0 clxscore=1011 classifier=spam authscore=0 authtc=n/a authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2505280000 definitions=main-2507230092 On 7/22/2025 5:01 PM, Komal Bajaj wrote: > EUD_MODE_MANAGER2 register is mapped to a memory region that is marked > as read-only for operating system running at EL1, enforcing access > restrictions that prohibit direct memory-mapped writes via writel(). > > Attempts to write to this region from HLOS can result in silent failures > or memory access violations, particularly when toggling EUD (Embedded > USB Debugger) state. To ensure secure register access, modify the driver > to use qcom_scm_io_writel(), which routes the write operation to Qualcomm > Secure Channel Monitor (SCM). SCM has the necessary permissions to access > protected memory regions, enabling reliable control over EUD state. > > SC7280, the only user of EUD is also affected, indicating that this could > never have worked on a properly fused device. > > Fixes: 9a1bf58ccd44 ("usb: misc: eud: Add driver support for Embedded USB Debugger(EUD)") > Signed-off-by: Melody Olvera > Signed-off-by: Komal Bajaj > Reviewed-by: Konrad Dybcio > --- Reviewed-by: Souradeep Chowdhury > Changes in v7: > - Updated the commit message as per Greg's comment > - Link to v6: https://lore.kernel.org/r/20250721-eud_mode_manager_secure_access-v6-1-fe603325ac04@oss.qualcomm.com > > Changes in v6: > - Propagating the error code from disable_eud(), per Dmitry's suggestion > - Link to v5: https://lore.kernel.org/r/20250715-eud_mode_manager_secure_access-v5-1-e769be308d4a@oss.qualcomm.com > > usb: misc: qcom_eud: Access EUD_MODE_MANAGER2 through secure calls > > Changes in v5: > * Changed select QCOM_SCM to depends on QCOM_SCM in Kconfig per Greg's review > * Link to v4: https://lore.kernel.org/all/20250709065533.25724-1-komal.bajaj@oss.qualcomm.com/ > > Changes in v4: > * Added error logging in disable_eud() for SCM write failures, per Konrad’s suggestion > * Link to v3: https://lore.kernel.org/all/20250708085208.19089-1-komal.bajaj@oss.qualcomm.com/ > > Changes in v3: > * Moved secure write before normal writes > * Added error checking in disable_eud() > * Use ENOMEM error code if platform_get_resource() fails > * Select QCOM_SCM driver if USB_QCOM_EUD is enabled > * Link to v2: https://lore.kernel.org/all/20250627125131.27606-1-komal.bajaj@oss.qualcomm.com/ > > Changes in v2: > * Drop separate compatible to be added for secure eud > * Use secure call to access EUD mode manager register > * Link to v1: https://lore.kernel.org/all/20240807183205.803847-1-quic_molvera@quicinc.com/ > --- > drivers/usb/misc/Kconfig | 1 + > drivers/usb/misc/qcom_eud.c | 33 ++++++++++++++++++++++++--------- > 2 files changed, 25 insertions(+), 9 deletions(-) > > diff --git a/drivers/usb/misc/Kconfig b/drivers/usb/misc/Kconfig > index 6497c4e81e951a14201ad965dadc29f9888f8254..73ebd3257625e4567f33636cdfd756344b9ed4e7 100644 > --- a/drivers/usb/misc/Kconfig > +++ b/drivers/usb/misc/Kconfig > @@ -147,6 +147,7 @@ config USB_APPLEDISPLAY > config USB_QCOM_EUD > tristate "QCOM Embedded USB Debugger(EUD) Driver" > depends on ARCH_QCOM || COMPILE_TEST > + depends on QCOM_SCM > select USB_ROLE_SWITCH > help > This module enables support for Qualcomm Technologies, Inc. > diff --git a/drivers/usb/misc/qcom_eud.c b/drivers/usb/misc/qcom_eud.c > index 83079c414b4f281b2136d0d1eb39418c7f94ff8c..05c8bdc943a88dab6159a05c2d770484c084f7b7 100644 > --- a/drivers/usb/misc/qcom_eud.c > +++ b/drivers/usb/misc/qcom_eud.c > @@ -15,6 +15,7 @@ > #include > #include > #include > +#include > > #define EUD_REG_INT1_EN_MASK 0x0024 > #define EUD_REG_INT_STATUS_1 0x0044 > @@ -34,7 +35,7 @@ struct eud_chip { > struct device *dev; > struct usb_role_switch *role_sw; > void __iomem *base; > - void __iomem *mode_mgr; > + phys_addr_t mode_mgr; > unsigned int int_status; > int irq; > bool enabled; > @@ -43,18 +44,29 @@ struct eud_chip { > > static int enable_eud(struct eud_chip *priv) > { > + int ret; > + > + ret = qcom_scm_io_writel(priv->mode_mgr + EUD_REG_EUD_EN2, 1); > + if (ret) > + return ret; > + > writel(EUD_ENABLE, priv->base + EUD_REG_CSR_EUD_EN); > writel(EUD_INT_VBUS | EUD_INT_SAFE_MODE, > priv->base + EUD_REG_INT1_EN_MASK); > - writel(1, priv->mode_mgr + EUD_REG_EUD_EN2); > > return usb_role_switch_set_role(priv->role_sw, USB_ROLE_DEVICE); > } > > -static void disable_eud(struct eud_chip *priv) > +static int disable_eud(struct eud_chip *priv) > { > + int ret; > + > + ret = qcom_scm_io_writel(priv->mode_mgr + EUD_REG_EUD_EN2, 0); > + if (ret) > + return ret; > + > writel(0, priv->base + EUD_REG_CSR_EUD_EN); > - writel(0, priv->mode_mgr + EUD_REG_EUD_EN2); > + return 0; > } > > static ssize_t enable_show(struct device *dev, > @@ -82,11 +94,12 @@ static ssize_t enable_store(struct device *dev, > chip->enabled = enable; > else > disable_eud(chip); > + > } else { > - disable_eud(chip); > + ret = disable_eud(chip); > } > > - return count; > + return ret < 0 ? ret : count; > } > > static DEVICE_ATTR_RW(enable); > @@ -178,6 +191,7 @@ static void eud_role_switch_release(void *data) > static int eud_probe(struct platform_device *pdev) > { > struct eud_chip *chip; > + struct resource *res; > int ret; > > chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL); > @@ -200,9 +214,10 @@ static int eud_probe(struct platform_device *pdev) > if (IS_ERR(chip->base)) > return PTR_ERR(chip->base); > > - chip->mode_mgr = devm_platform_ioremap_resource(pdev, 1); > - if (IS_ERR(chip->mode_mgr)) > - return PTR_ERR(chip->mode_mgr); > + res = platform_get_resource(pdev, IORESOURCE_MEM, 1); > + if (!res) > + return -ENODEV; > + chip->mode_mgr = res->start; > > chip->irq = platform_get_irq(pdev, 0); > if (chip->irq < 0) > > --- > base-commit: 347e9f5043c89695b01e66b3ed111755afcf1911 > change-id: 20250715-eud_mode_manager_secure_access-6e57e3c71ec2 > > Best regards,