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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 021E3CDE00E for ; Fri, 26 Jun 2026 08:48:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=/S2xp6uP+NnDpHnkVhvd3u/16+/JYV8Sjg9E05AV+CY=; b=Suh3zPTP/SnYbJmhRGwJ3weflh Oky3zW1+UlJIfcN7zIlzVUVN6x2D5y1FImhmUO1wzO3A6xMajcBgETfyAp+4F3lK46up/QleIzHOp WTIXzM2Ym3NPA9Y/oXU5EYTMXprd3UJ9hNSdyrWifHnh5eNmt33D8Wu+0puh1VslhE1+49lx8Kog+ I5bcJdw/coKCOTEPLL13+KAIh4tzSjmDJWXS9bX4CXhzIL1c6nRkJMGaApVWIu31NDZG8lvJ/7XCC ohKVnOSjexfa1VjUF2IvPgwy8D0pvZhLbZSNGjYW/wSx9ZdCxb+1mL20naahwOBbAKajLUJkgOm4o iLcTrKXw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wd2Et-0000000Aubk-2Qhd; Fri, 26 Jun 2026 08:48:43 +0000 Received: from stravinsky.debian.org ([2001:41b8:202:deb::311:108]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wd2Eq-0000000Aub3-3HXm; Fri, 26 Jun 2026 08:48:42 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=debian.org; s=smtpauto.stravinsky; h=X-Debian-User:In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=/S2xp6uP+NnDpHnkVhvd3u/16+/JYV8Sjg9E05AV+CY=; b=rm3wMVYaU1oJmUW30/iLkgC8tW 7+nUXiZkXvcke485Uvum75qA/elqGgphrlJfHTBzMEA1UvJ1Jf8WVju41IKgBn2hTxrEub4VTd3s0 YL/4hcAOtKDB33Aj9WcSyQZfdSEz6TqK/GwHbiaUDotC6dBsyO//eJpotx7vqDie39FWM9Tzm4XHS D2Km03J/B1aVTtxyHzzIOVJ1uDq+A90eDG2BDt57WhAV8LOtj7pwlMYNA+K5q1AJc4VijF/okauZY iIAslLsevZHHzxRCb0XsyW3gPXJLVLGth3PyeKZ99biSJyk2rVPiZoEzcBZavQ00pi0Dr8TcrMybU li1RBlEA==; Received: from authenticated-user by stravinsky.debian.org with esmtpsa (TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.96) (envelope-from ) id 1wd2Ea-003qhi-15; Fri, 26 Jun 2026 08:48:24 +0000 Date: Fri, 26 Jun 2026 01:48:17 -0700 From: Breno Leitao To: Doug Anderson , kernel-team@meta.com Cc: Kiryl Shutsemau , Marc Zyngier , Catalin Marinas , Will Deacon , James Morse , Mark Rutland , Petr Mladek , Thomas Gleixner , Andrew Morton , Baoquan He , Puranjay Mohan , Usama Arif , Julien Thierry , Lecopzer Chen , Sumit Garg , kernel-team@meta.com, kexec@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, paulmck@kernel.org, rmikey@meta.com Subject: Re: [PATCH v4 0/4] arm64: cross-CPU NMI via SDEI Message-ID: References: <868q8asj1u.wl-maz@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Debian-User: leitao X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260626_014840_826086_AE40AA53 X-CRM114-Status: UNSURE ( 8.18 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Jun 22, 2026 at 09:52:40AM -0700, Doug Anderson wrote: > Having them as a stop-gap until true NMI is available > seems nice to me I completely agree. Should these patches unfortunately not make it upstream, my plan is to maintain them downstream at Meta kernels until the Meta fleet no longer contains any non-FEAT_NMI hosts. The trade-offs under consideration are: 1) Accept the performance overhead from pseudo-NMI 2) Lose debuggability by disabling NMI entirely 3) Maintain downstream patches Of these three options, carrying downstream patches appears to be the least disruptive path for our business needs.