From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from stravinsky.debian.org (stravinsky.debian.org [82.195.75.108]) (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 AFC27286415 for ; Fri, 26 Jun 2026 08:48:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=82.195.75.108 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782463720; cv=none; b=MzD1YHK8u31Epo4JcJrED76LTj9aadDWZcf4dqQ3uZUbhIjtsHZ7+f0vVT7vlGH58MUSpCUXg8QKlUExQeEsDjHnOp6N4EU+10DnkxSVzAD2MkhGZ1kZ2vaNe6iG+dWA4Xlkp2CeoVO942oUIajfpS8YyPmDWsbypa0VB25Zuj8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782463720; c=relaxed/simple; bh=Qc1dP9pgZRB+jGRshUBWiRSTUzmZg/s3leRKv6PhdI8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=c9r+YFR6EYlozBBcEsL9sIl69HGSFk6EHssjFSfHzTFFoVBXo6WguhgA5/Vg0OIiy97fz3cUeaDHYkjGp2YHxyw7659NMkkMdu/pbXmtfvy0WBLia8WI1CByf44HdVUaGSdeDQsSf912QfJJFoEicpQ/Jjo2x17U064rKbxQ71A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=debian.org; spf=pass smtp.mailfrom=debian.org; dkim=pass (2048-bit key) header.d=debian.org header.i=@debian.org header.b=rm3wMVYa; arc=none smtp.client-ip=82.195.75.108 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=debian.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=debian.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=debian.org header.i=@debian.org header.b="rm3wMVYa" 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> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Debian-User: leitao 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.