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 3E1E8C021B8 for ; Sat, 1 Mar 2025 18:11:28 +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:Content-Type:MIME-Version: Message-ID:Date:References:In-Reply-To:Subject:Cc:To:From: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=7aAluflwF8uxqGPtsL2kQpy/Mt+z1OejY+ngR/xlVwA=; b=XwnK2aZCeFJf/F2k3DJVJ2+tfj z0lwOjL3IionyuoN9+GF0CQfE3MT+tLLqrfAgD0JwYo4Y+Wzo7GUd6LJB8eEf5wPL2dZDbLDZMNfg yFTuJu4PEMb0wfofjK0gj0GwOeaB9CXId6+tC5ojlIzVPDnnhEHDLUp8nVXkOS3a+p4iy4sZeG2ZN 8q4lNDrbozY04SqP8WZWorYahSLAmCQ7nMkDTw7kGjVSWTpdKA4LAXFzm6rjVDiiDxvFh+g+Ekpjn 2hCDRli3G4A6AH9yO+DWvExs5qdmIZOultFGIT7zhQ4O+kn1UQDIYsPvQWV6SrSq8svuOi1S04v3g EdJxCP7g==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1toRJ0-0000000EkEL-2khp; Sat, 01 Mar 2025 18:11:18 +0000 Received: from galois.linutronix.de ([193.142.43.55]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1toRHQ-0000000Ek6u-3s5c for linux-arm-kernel@lists.infradead.org; Sat, 01 Mar 2025 18:09:42 +0000 From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1740852577; 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=7aAluflwF8uxqGPtsL2kQpy/Mt+z1OejY+ngR/xlVwA=; b=wpczwOyWMsIC5xL2dzr/GEWVo681ybJMAa+f0e7K8fW51ZCfsUYSjDzvjIhWIvq2ud7yW+ 9VbEDuNAYHIvhW7Xe4XhLYvHHR/YuPwqoL2uKsN58NaK3dLwf/3or9U9jMJBD5r7KJj3dL WozYGrEoI0Q0QucZF5/RohIu1r5+xRbrpV3Oh8RocPpEVrsn+PjYpQmY4TW98MS0v9NwGs cOPceCK9wps63cE0Ah0F2Dw3hGQ+hT4dxWRdeOBj2IF7lE7lvWCEf3CM8GnKCu9C7ifbbB ycoHiW6RLyj+I6mnW4e4PsfoxEsh8Xru4haSb334UuKdXhW03TjurxMEgkEChg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1740852577; 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=7aAluflwF8uxqGPtsL2kQpy/Mt+z1OejY+ngR/xlVwA=; b=bOD5z77+FsiaBwISDB+ppOhZwXZLsW93CjTdva9DyZjaS2IgUkbkM357Wb/3WsV+YQlN8Y mMHtAgK+F3jkw3Aw== To: Marc Zyngier , Frank Li Cc: Kishon Vijay Abraham I , "Rafael J. Wysocki" , Anup Patel , Greg Kroah-Hartman , Danilo Krummrich , Manivannan Sadhasivam , Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= , Bjorn Helgaas , Arnd Bergmann , Shuah Khan , Richard Zhu , Lucas Stach , Lorenzo Pieralisi , Rob Herring , Shawn Guo , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , Krzysztof Kozlowski , Conor Dooley , Niklas Cassel , dlemoal@kernel.org, jdmason@kudzu.us, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-pci@vger.kernel.org, linux-kselftest@vger.kernel.org, imx@lists.linux.dev, devicetree@vger.kernel.org Subject: Re: [PATCH v15 00/15] PCI: EP: Add RC-to-EP doorbell with platform MSI controller In-Reply-To: <86ldtpot6m.wl-maz@kernel.org> References: <20250211-ep-msi-v15-0-bcacc1f2b1a9@nxp.com> <86ldtpot6m.wl-maz@kernel.org> Date: Sat, 01 Mar 2025 19:09:35 +0100 Message-ID: <87senwd3mo.ffs@tglx> MIME-Version: 1.0 Content-Type: text/plain X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250301_100941_109417_89AC2BA5 X-CRM114-Status: UNSURE ( 9.56 ) 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 Sat, Mar 01 2025 at 12:02, Marc Zyngier wrote: > - This IMMUTABLE thing serves no purpose, because you don't randomly > plug this end-point block on any MSI controller. They come as part > of an SoC. Yes and no. The problem is that the EP implementation is meant to be a generic library and while GIC-ITS guarantees immutability of the address/data pair after setup, there are architectures (x86, loongson, riscv) where the base MSI controller does not and immutability is only achieved when interrupt remapping is enabled. The latter can be disabled at boot-time and then the EP implementation becomes a lottery across affinity changes. That was my concern about this library implementation and that's why I asked for a mechanism to ensure that the underlying irqdomain provides a immutable address/data pair. So it does not matter for GIC-ITS, but in the larger picture it matters. Thanks, tglx