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 5AF52CD128A for ; Thu, 11 Apr 2024 09:55:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=KukPlRd8Z6fSFqJB20ffLWPEr5wyTXonU0PqBO2JFCE=; b=2k6s4cScBXHEW5 0dmKEnvhP31IA3ykC5bmFkkigU8zax4LOlSMZhO+6UC63LmDabGPFKA6xkW3aMxF14rfRdXKYLBOy KJTLrE/Yd7qC5ap632i27WHmvbRPHASjG2X02dlpRUyTU5Ozro6nLoPxtZTtANYYlcWBZ1RBisbrE OXiDl5XhGL4/s9VotFm+1m+hQgoAlXn3zyq26WmFu0X1+mX4ro3Ykj9vJ0f9kv+oHGO9JM4pES/1r QstQIm+C9YXVwtE7eLDqztwOkz2MlxvZkSuKSgl0ojoSXg93LMaoXQQQswABZzne/oBTjEVktoQFh 8dZRp7nPn0/kpu9ZvAsQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1rur92-0000000BPco-0SRE; Thu, 11 Apr 2024 09:55:00 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1rur8y-0000000BPcF-44Lt for linux-arm-kernel@lists.infradead.org; Thu, 11 Apr 2024 09:54:58 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 93C19113E; Thu, 11 Apr 2024 02:55:25 -0700 (PDT) Received: from bogus (e103737-lin.cambridge.arm.com [10.1.197.49]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 1066B3F6C4; Thu, 11 Apr 2024 02:54:54 -0700 (PDT) Date: Thu, 11 Apr 2024 10:54:52 +0100 From: Sudeep Holla To: linux-arm-kernel@lists.infradead.org Cc: Marc Bonnici , Olivier Deprez , Sudeep Holla , Lorenzo Pieralisi , Bertrand Marquis , Jens Wiklander Subject: Re: [PATCH 3/3] firmware: arm_ffa: Add support for handling notification pending interrupt(NPI) Message-ID: References: <20240410-ffa_npi_support-v1-0-1a5223391bd1@arm.com> <20240410-ffa_npi_support-v1-3-1a5223391bd1@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20240410-ffa_npi_support-v1-3-1a5223391bd1@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240411_025457_068120_2174483E X-CRM114-Status: GOOD ( 16.32 ) 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: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Apr 10, 2024 at 12:39:48PM +0100, Sudeep Holla wrote: > The FF-A uses the notification pending interrupt to inform the receiver > that it has a pending notification. This is a virtual interrupt and is > used by the following type of receivers: > 1. A guest/VM running under a hypervisor. > 2. An S-EL1 SP running under a S-EL2 SPMC. > > The rules that govern the properties of the NPI are the same as the > rules for the SRI with couple of exceptions. If the SRI is not supported, > then an attempt to discover NPI will be made in the driver. > > The handling of NPI is also same as the handling of notification for the > self/primary VM with ID 0 except the absence of global notification. > OK I think I rushed to send this. Bertrand had now convinced me with a use case that needs the support for both SRI and NPI in the driver. XEN hypervisor can inject both SRI and NPI to the Dom0. The choice of NPI over SRI is to avoid the context switch latency with the FFA_NOTIFICATION_INFO_GET as NPI will just need FFA_NOTIFICATION_GET which may completely avoid switching to secure side as XEN hyp handles the same. -- Regards, Sudeep _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel