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 E8274C282D1 for ; Thu, 6 Mar 2025 10:49:06 +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-Transfer-Encoding:Content-Type: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=GBrhVrT9tMuG0jg3VSUDHwK+uoJGEzQebSg70uIDDjA=; b=s/Zq4ysAlTXHL3TBd9cngES2qa NiHUsDuStHKxHgEKYvY2l76rHtSbxUvtOg0qlPxZ15RuxpumxtXWSC6DW+UayRKqU2VN6YxGbvj9x 2/2QUfSCWXgJ2AfyEYiw20afNGEAoEcBmRNCJyZgab/w7IFKzmD/Z+5j6HKSZGQhi7wX+sRCwu4PE f5kOYc4ouYFcjLjfM6bKdMZ4vY8EDiNf/IuFMXSPw//5CyLv9ewKcV6nTkF5t6IxJobVHaE94a1J8 iIj5WjsElTuv407U5gZoG0S3JduRdkoVfsgpz56r7jOk/oyhAiv61Jn2wVjTreNbPfVpGQcuimpPQ 5o2Zf0pA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tq8md-0000000Aghr-3L6a; Thu, 06 Mar 2025 10:48:55 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tq7im-0000000AW27-2004 for linux-arm-kernel@lists.infradead.org; Thu, 06 Mar 2025 09:40:53 +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 44C30FEC; Thu, 6 Mar 2025 01:41:02 -0800 (PST) Received: from bogus (e133711.arm.com [10.1.196.55]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 9CA433F673; Thu, 6 Mar 2025 01:40:46 -0800 (PST) Date: Thu, 6 Mar 2025 09:40:43 +0000 From: Sudeep Holla To: Will Deacon Cc: Sebastian Ene , catalin.marinas@arm.com, Sudeep Holla , joey.gouly@arm.com, maz@kernel.org, oliver.upton@linux.dev, snehalreddy@google.com, suzuki.poulose@arm.com, vdonnefort@google.com, yuzenghui@huawei.com, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kernel-team@android.com, Andrei Homescu Subject: Re: [PATCH v2 4/4] KVM: arm64: Release the ownership of the hyp rx buffer to Trustzone Message-ID: References: <20250227181750.3606372-1-sebastianene@google.com> <20250227181750.3606372-5-sebastianene@google.com> <20250305004522.GC31667@willie-the-truck> <20250305094104.vctshdtgdukno2aj@bogus> <20250305193425.GA32246@willie-the-truck> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20250305193425.GA32246@willie-the-truck> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250306_014052_556543_8CB59527 X-CRM114-Status: GOOD ( 22.00 ) 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 Wed, Mar 05, 2025 at 07:34:26PM +0000, Will Deacon wrote: > On Wed, Mar 05, 2025 at 09:41:04AM +0000, Sudeep Holla wrote: > > On Wed, Mar 05, 2025 at 12:45:23AM +0000, Will Deacon wrote: > > > Hmm, the FFA spec is characteristically unclear as to whether or not we > > > need to release the rx buffer in the case that the flags indicate use of > > > the rx buffer but the returned partition count is 0. > > > > > > Sudeep -- do you know what we should be doing in that case? > > > > > > > We need to call RX_RELEASE here. I went back to the spec to confirm the > > same again. > > > > v1.2 EAC0 spec Section 7.2.2.4.2 Transfer of buffer ownership > > (Or just look for the section title in any version of the spec) > > " > > 2. Ownership transfer for the RX buffer takes place as follows. > > 2. For a framework message, > > 1. Completion of the FFA_PARTITION_INFO_GET ABI transfers the ownership > > of the caller’s RX buffer from the Producer to the Consumer. > > 3. For both types of messages, an invocation of the following FF-A ABIs > > transfers the ownership from the Consumer to the Producer. > > 1. FFA_MSG_WAIT ... > > 2. FFA_RX_RELEASE. > > " > > > > Hope that helps, can dig deeper if there are any ambiguities around this. > > Thanks Sudeep, but that also makes it sound like we need the RX_RELEASE > even if we're not using the RX buffer per the input flags. :/ > Good spot, I had forgotten about the input flags that can avoid using the buffer. I will see if we can improve the spec in that regards. -- Regards, Sudeep