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Wed, 5 Mar 2025 09:02:41 GMT Received: from smtpav02.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 5396820040; Wed, 5 Mar 2025 09:02:41 +0000 (GMT) Received: from smtpav02.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 8AD1A20043; Wed, 5 Mar 2025 09:02:39 +0000 (GMT) Received: from li-c6426e4c-27cf-11b2-a85c-95d65bc0de0e.in.ibm.com (unknown [9.204.206.66]) by smtpav02.fra02v.mail.ibm.com (Postfix) with ESMTP; Wed, 5 Mar 2025 09:02:39 +0000 (GMT) From: Gautam Menghani To: maddy@linux.ibm.com, mpe@ellerman.id.au, npiggin@gmail.com, christophe.leroy@csgroup.eu, naveen@kernel.org Cc: Gautam Menghani , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, vaibhav@linux.ibm.com Subject: [PATCH] powerpc/pseries/msi: Avoid reading PCI device registers in reduced power states Date: Wed, 5 Mar 2025 14:32:36 +0530 Message-ID: <20250305090237.294633-1-gautam@linux.ibm.com> X-Mailer: git-send-email 2.47.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-GUID: XMEYmXGLWR-uqDp97woI17Cud8XvfrSk X-Proofpoint-ORIG-GUID: qBkNYmHN-zrEB8W6tWAMSOdOUG5YmdZY X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1093,Hydra:6.0.680,FMLib:17.12.68.34 definitions=2025-03-05_03,2025-03-05_01,2024-11-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 phishscore=0 bulkscore=0 lowpriorityscore=0 suspectscore=0 clxscore=1015 malwarescore=0 mlxscore=0 impostorscore=0 adultscore=0 priorityscore=1501 mlxlogscore=999 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2502100000 definitions=main-2503050071 Content-Type: text/plain; charset="utf-8" When a system is being suspended to RAM, the PCI devices are also suspended and the PPC code ends up calling pseries_msi_compose_msg() and this triggers the BUG_ON() in __pci_read_msi_msg() because the device at this point is in reduced power state. In reduced power state, the memory mapped registers of the PCI device are not accessible. To replicate the bug: 1. Make sure deep sleep is selected # cat /sys/power/mem_sleep s2idle [deep] 2. Make sure console is not suspended (so that dmesg logs are visible) echo N > /sys/module/printk/parameters/console_suspend 3. Suspend the system echo mem > /sys/power/state To fix this behaviour, read the cached msi message of the device when the device is not in PCI_D0 power state instead of touching the hardware. Fixes: a5f3d2c17b07 ("powerpc/pseries/pci: Add MSI domains") Cc: stable@vger.kernel.org # v5.15+ Signed-off-by: Gautam Menghani Reviewed-by: Vaibhav Jain Tested-by: Venkat Rao Bagalkote --- arch/powerpc/platforms/pseries/msi.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/platforms/pseries/msi.c b/arch/powerpc/platforms/= pseries/msi.c index fdc2f7f38dc9..458d95c8c755 100644 --- a/arch/powerpc/platforms/pseries/msi.c +++ b/arch/powerpc/platforms/pseries/msi.c @@ -525,7 +525,12 @@ static struct msi_domain_info pseries_msi_domain_info = =3D { =20 static void pseries_msi_compose_msg(struct irq_data *data, struct msi_msg = *msg) { - __pci_read_msi_msg(irq_data_get_msi_desc(data), msg); + struct pci_dev *dev =3D msi_desc_to_pci_dev(irq_data_get_msi_desc(data)); + + if (dev->current_state =3D=3D PCI_D0) + __pci_read_msi_msg(irq_data_get_msi_desc(data), msg); + else + get_cached_msi_msg(data->irq, msg); } =20 static struct irq_chip pseries_msi_irq_chip =3D { --=20 2.47.0