From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 31B89CA5FD4 for ; Fri, 2 Oct 2026 13:30:31 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.1439136.1657589 (Exim 4.92) (envelope-from ) id 1xCdL9-0006V0-G1; Fri, 02 Oct 2026 13:30:19 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 1439136.1657589; Fri, 02 Oct 2026 13:30:19 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1xCdL9-0006Ut-DD; Fri, 02 Oct 2026 13:30:19 +0000 Received: by outflank-mailman (input) for mailman id 1439136; Fri, 02 Oct 2026 13:30:17 +0000 Received: from mail.xenproject.org ([104.130.215.37]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1xCdL7-0006Un-O1 for xen-devel@lists.xenproject.org; Fri, 02 Oct 2026 13:30:17 +0000 Received: from xenbits.xenproject.org ([104.239.192.120]) by mail.xenproject.org with esmtp (Exim 4.96) (envelope-from ) id 1xCdL3-00B8dt-0Z; Fri, 02 Oct 2026 13:30:13 +0000 Received: from 224.pool85-54-217.dynamic.orange.es ([85.54.217.224] helo=localhost) by xenbits.xenproject.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1xCdL2-00BgHY-2C; Fri, 02 Oct 2026 13:30:13 +0000 X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=xenproject.org; s=20200302mail; h=In-Reply-To:Content-Transfer-Encoding: Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date; bh=B+ryK4cNzLrxJOPKW+kaF8YUKQUNuiDy7z0zKhxK+V4=; b=b+VhN9NxHWK3tskMdVI3bHIhJQ U2iCc6hpmd7uDLBqAVcQxWbSCGFvRuty+s0F46CMLXQDxoezfD12falIunEvIhLefgicJWjr8A7RI e+kNcr/xRV5eJZzelzvNINBHxD2WKtAbELuCMJvXC0FgSlcuJynZcLlvS2PniZiXKL/4=; Date: Fri, 2 Oct 2026 15:30:02 +0200 From: Roger Pau =?utf-8?B?TW9ubsOp?= To: Jan Beulich Cc: Grygorii Strashko , Andrew Cooper , Teddy Astie , xen-devel@lists.xenproject.org Subject: Re: [PATCH v2] x86/domain: restrict context switch hooks for the idle domain Message-ID: References: <20261002112005.20656-1-roger@xenproject.org> <8e26f887-453b-47cc-aaea-6c6675d9f9a5@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <8e26f887-453b-47cc-aaea-6c6675d9f9a5@suse.com> On Fri, Oct 02, 2026 at 01:33:42PM +0200, Jan Beulich wrote: > On 02.10.2026 13:20, Roger Pau Monne wrote: > > From: Grygorii Strashko > > > > The arch_init_idle_domain() initializes struct arch_csw idle_csw as: > > > > static const struct arch_csw idle_csw = { > > .from = paravirt_ctxt_switch_from, > > .to = paravirt_ctxt_switch_to, > > .tail = idle_loop, > > }; > > > > but only place where d->arch.ctxt_switch->{to,from}() are used is > > __context_switch() where they are both guarded by !is_idle_domain(pd) > > which makes the callbacks in idle_csw unreachable. > > > > Introduce a new poison value to be used in unreachable function hooks, and > > set the from/to fields of idle_csw to it. Use a different value from the > > currently defined ones for easy differentiation. > > > > Signed-off-by: Grygorii Strashko > > Signed-off-by: Roger Pau Monné > > Reviewed-by: Jan Beulich > provided this doesn't raise new Misra violations, including for rules which > aren't entirely clean yet, but which are actively being worked on. I've wondered the same, but since your recent change in: 68c3f7fb3a84 Eclair: relax long <-> function-pointer conversion deviation I think it should be fine? I will run a CI loop first anyway. Thanks, Roger.