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X-CSE-ConnectionGUID: 7bU8ay3dTDeCOMf0K6XW9w== X-CSE-MsgGUID: Dba8QaI4Q/Kj2oga681wmQ== X-IronPort-AV: E=McAfee;i="6800,10657,11821"; a="82781144" X-IronPort-AV: E=Sophos;i="6.24,212,1774335600"; d="scan'208";a="82781144" Received: from orviesa001.jf.intel.com ([10.64.159.141]) by fmvoesa109.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Jun 2026 14:35:30 -0700 X-CSE-ConnectionGUID: FBJllL8bQo2yQd//EB90xQ== X-CSE-MsgGUID: ZFPs+9BtRW2MhaGxo3t5Kw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.24,212,1774335600"; d="scan'208";a="286590281" Received: from rfrazer-mobl3.amr.corp.intel.com (HELO [10.125.111.222]) ([10.125.111.222]) by smtpauth.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Jun 2026 14:35:29 -0700 Message-ID: <49380c3e-c275-4211-876a-c51f644aeb17@intel.com> Date: Thu, 18 Jun 2026 14:35:28 -0700 Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v8 3/7] crypto/ccp: Disable CPU hotplug while SNP is active To: Ashish Kalra , tglx@kernel.org, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, seanjc@google.com, peterz@infradead.org, thomas.lendacky@amd.com, herbert@gondor.apana.org.au, davem@davemloft.net, ardb@kernel.org Cc: pbonzini@redhat.com, aik@amd.com, Michael.Roth@amd.com, KPrateek.Nayak@amd.com, Tycho.Andersen@amd.com, Nathan.Fontenot@amd.com, ackerleytng@google.com, jackyli@google.com, pgonda@google.com, rientjes@google.com, jacobhxu@google.com, xin@zytor.com, pawan.kumar.gupta@linux.intel.com, babu.moger@amd.com, dyoung@redhat.com, nikunj@amd.com, john.allen@amd.com, darwi@linutronix.de, linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org, kvm@vger.kernel.org, linux-coco@lists.linux.dev References: <1feccf6e2a56d949b30f403c0ca7949f580e5982.1781419998.git.ashish.kalra@amd.com> Content-Language: en-US From: Dave Hansen Autocrypt: addr=dave.hansen@intel.com; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 6/15/26 12:49, Ashish Kalra wrote: > + /* > + * Disable CPU hotplug while SNP is active. Guard against stacking > + * the disable count: the legacy SNP_SHUTDOWN_EX path clears > + * snp_initialized without re-enabling hotplug, so this can run > + * again while hotplug is already disabled. > + */ > + if (!snp_cpu_hotplug_disabled) { > + cpu_hotplug_disable(); > + snp_cpu_hotplug_disabled = true; > + } This seems like a hack, guys. cpu_hotplug_disable() seems like more of a temporary lock than enforcing basically permanent system state. This seems like it would be better implemented by registering a CPU hotplug callback and then refusing to offline if sev->snp_initialized is set. snp_setup_rmpopt() can be run any time, right? It doesn't need to be after sev->snp_initialized=1.