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Tue, 28 Oct 2025 04:08:39 +0000 (GMT) Date: Tue, 28 Oct 2025 09:38:38 +0530 From: Srikar Dronamraju To: "Nysal Jan K.A." Cc: Sourabh Jain , Madhavan Srinivasan , Christophe Leroy , Sachin P Bappalige , stable@vger.kernel.org, Michael Ellerman , Nicholas Piggin , Laurent Dufour , Thomas Gleixner , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] powerpc/kexec: Enable SMT before waking offline CPUs Message-ID: Reply-To: Srikar Dronamraju References: <20251025080512.85690-1-nysal@linux.ibm.com> X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20251025080512.85690-1-nysal@linux.ibm.com> X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=JqL8bc4C c=1 sm=1 tr=0 ts=690041cf cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=8nJEP1OIZ-IA:10 a=x6icFKpwvdMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=VnNF1IyMAAAA:8 a=eMohRQ-KdQCHCDRkyAgA:9 a=wPNLvfGTeEIA:10 a=cPQSjfK2_nFv0Q5t_7PE:22 X-Proofpoint-GUID: t6S93ipUKAohD0zxwgjOAjKz4Lz5HzZN X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUxMDI1MDAxOSBTYWx0ZWRfXytRsWE3y5MiL cLymIho//XHObODNhoDqSk755gVf/wGRaaB4aw/GKUCfAXOBrxQNL/5U9dmtNjTRc1NusopCVm8 p5dt/NOKfbSPVJIzXlTdwCMqMlkfdW8AQeJWUi1LQGb6G9a8GjpHCUQCTWBuhAVfSKD3vf9dFHh PW662LWPWr/IFJmquAHceEOv2qQG/KykEpcV+TPjxaAeXi9VMS56+OuYraz15aqeNd9dpuQPnT4 KM7yShxtocfo0nGFsjMuBUc6kZ7P3gLco/JTdNBLyO14kyMFg5b45D/TLFKiscJMdLym+Qs9IVx cRYn7Zf/jtRM4wjx0KX61MVnwvcGB1F35Mg1M0TS8WhP2JbTKTi6RglcAK7rlrgBo2TeagMCByS Kfo/fbXz0GSObpOBjO1KY3WXS5wHKw== X-Proofpoint-ORIG-GUID: OAhCU3nbnwm1qIWiPiQBU9lbZaSH1Nz6 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-10-28_02,2025-10-22_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 clxscore=1011 lowpriorityscore=0 malwarescore=0 bulkscore=0 priorityscore=1501 spamscore=0 adultscore=0 phishscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2510020000 definitions=main-2510250019 * Nysal Jan K.A. [2025-10-25 13:35:09]: > diff --git a/arch/powerpc/kexec/core_64.c b/arch/powerpc/kexec/core_64.c > index 222aa326dace..ff6df43720c4 100644 > --- a/arch/powerpc/kexec/core_64.c > +++ b/arch/powerpc/kexec/core_64.c > @@ -216,6 +216,11 @@ static void wake_offline_cpus(void) > { > int cpu = 0; > > + lock_device_hotplug(); > + cpu_smt_num_threads = threads_per_core; > + cpu_smt_control = CPU_SMT_ENABLED; > + unlock_device_hotplug(); > + Nit: can we add a comment mentioning why we do it and probably move to a small helper function of its own. Otherwise looks good. Reviewed-by: Srikar Dronamraju > for_each_present_cpu(cpu) { > if (!cpu_online(cpu)) { > printk(KERN_INFO "kexec: Waking offline cpu %d.\n", -- Thanks and Regards Srikar Dronamraju