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b=irYoaUH4lhEufBk+QKM4fc4DVCjSj4nza6V8BYd0EsduLfUNSiHKRRLntJUTlDLD01YkV5NCpr1yvlM5pzTPp31/KVr9b56Zg0HGvqHMKuXK1LIBYj01oBD4Hld3hElfi/sEVYyMzeOTjv9CYaFcipkjHaqFv/ycQ6YQlhAzmiY= Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=amd.com; Received: from DS7PR12MB6214.namprd12.prod.outlook.com (2603:10b6:8:96::13) by MN2PR12MB4160.namprd12.prod.outlook.com (2603:10b6:208:19a::19) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.8792.36; Mon, 9 Jun 2025 06:39:42 +0000 Received: from DS7PR12MB6214.namprd12.prod.outlook.com ([fe80::17e6:16c7:6bc1:26fb]) by DS7PR12MB6214.namprd12.prod.outlook.com ([fe80::17e6:16c7:6bc1:26fb%3]) with mapi id 15.20.8792.034; Mon, 9 Jun 2025 06:39:41 +0000 Message-ID: <4f28e3bf-cbe1-42ce-b7f2-5cff86e635b7@amd.com> Date: Mon, 9 Jun 2025 12:09:35 +0530 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] kvm: preemption must be disabled when calling smp_call_function_many To: Salah Triki , Paolo Bonzini , kvm@vger.kernel.org, linux-kernel@vger.kernel.org References: Content-Language: en-US From: Manali Shukla In-Reply-To: Content-Type: text/plain; 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> > + preempt_disable(); > smp_call_function_many(cpus, ack_kick, NULL, wait); > + preempt_enable(); > + > return true; > } > Hi Salah, I noticed that kvm_kick_many_cpus() is only invoked from two locations (from kvm_make_vcpus_request_mask() and kvm_make_all_cpus_request(), and in both cases, get_cpu() is called prior to kvm_kick_many_cpus(), with a corresponding put_cpu() afterward. Since get_cpu() disables preemption and put_cpu() re-enables it, preemption is already disabled during the execution of kvm_kick_many_cpus(). Given that, could you clarify the motivation behind explicitly adding preempt_disable() and preempt_enable() within kvm_kick_many_cpus()? -Manali