From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 100D6D533 for ; Fri, 23 Feb 2024 10:28:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708684112; cv=none; b=sNicM2RjxcdCdqjWILuVvizkMqpsMb6uBsqzOcXVHhJYxFcfZf3YIODX3xYgzyTwbi1kE+nS4CFTXpdpEfhXOLn2ezFhUsH8jgkapo4bZaaoVSuKCv94Nahzk84iWrIxQ/pQh6YkWRoXlO6X9Jz+S3bA8duXbSYJnrhDbmWDYOM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708684112; c=relaxed/simple; bh=cl3yxDrq//HdjpH4tGpYeRfOCYCkzMKRoLj++ITknVc=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=osygKuPzUyQZqwujS/RUwo19IHKQdPGPtxQGvBSz4LWOJMr8/UrJFO8VW41f3VDbd8MXhmc7Tbm32zCy+yfP8q90WWq7kiap+jz5rxp4gQZNsh4c5B9FPY+wIYApiodyH6pTWrg1Hb5vEK3Izj4h5vM/xw3dDaURQGEmNeGRSEI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=U11EX3Gs; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=zbZmICsw; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="U11EX3Gs"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="zbZmICsw" From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1708684109; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=rCkSqOHXuNZNZ4qVAhXnw7igAzpOyBDOC7OEqD/cJhc=; b=U11EX3Gs7FK3ddaIS5hLCrLHSqX9h8fgsM12+dEprj9QStdLmwDUXgmjR6ptTQ6s+nm5aC KQp49Cg6YVxaAjH/FggpkbntKzvEAHfW6bH19BZzDvAuGvdzB+03XUxRqSvmR2KFlIjX7S 9Gfe8CkA4zwjNMOqiV5srnkr6hVd+9ayY9O3C8Cr80aK7dmjLqlS7hfTJ3Kiz3MKioJmpV BVSQrfb1dVuIo4kNHW7DeWpx9slJcF2TTTOtc0uEfH+u41wdotKzFo8PbmsAjdMlivK7zy kO1sbtUrK1bWMfz5VVUTE1/DrhsAVFxnaShTHZvnWn6cl1vs9bvbTe9exxnfgg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1708684109; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=rCkSqOHXuNZNZ4qVAhXnw7igAzpOyBDOC7OEqD/cJhc=; b=zbZmICswW00KhN+dV6Wcm66nBj+5YEQ3qEg6CAYuhnU5gj+g/sB9sxUv6UKb+ibV6/Tyl+ xLqpn93b+a658eBw== To: "Kirill A. Shutemov" , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org Cc: "Rafael J. Wysocki" , Peter Zijlstra , Adrian Hunter , Kuppuswamy Sathyanarayanan , Elena Reshetova , Jun Nakajima , Rick Edgecombe , Tom Lendacky , "Kalra, Ashish" , Sean Christopherson , "Huang, Kai" , Baoquan He , kexec@lists.infradead.org, linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org, "Kirill A. Shutemov" Subject: Re: [PATCHv7 13/16] x86/acpi: Do not attempt to bring up secondary CPUs in kexec case In-Reply-To: <20240212104448.2589568-14-kirill.shutemov@linux.intel.com> References: <20240212104448.2589568-1-kirill.shutemov@linux.intel.com> <20240212104448.2589568-14-kirill.shutemov@linux.intel.com> Date: Fri, 23 Feb 2024 11:28:28 +0100 Message-ID: <87msrrcw4z.ffs@tglx> Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain On Mon, Feb 12 2024 at 12:44, Kirill A. Shutemov wrote: > ACPI MADT doesn't allow to offline a CPU after it was onlined. This > limits kexec: the second kernel won't be able to use more than one CPU. > > To prevent a kexec kernel from onlining secondary CPUs invalidate the > mailbox address in the ACPI MADT wakeup structure which prevents a > kexec kernel to use it. > > This is safe as the booting kernel has the mailbox address cached > already and acpi_wakeup_cpu() uses the cached value to bring up the > secondary CPUs. > > Note: This is a Linux specific convention and not covered by the > ACPI specification. > > Signed-off-by: Kirill A. Shutemov > Reviewed-by: Kai Huang > Reviewed-by: Kuppuswamy Sathyanarayanan Reviewed-by: Thomas Gleixner