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 28D1CC54EE9 for ; Thu, 8 Sep 2022 13:29:32 +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:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject: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=HQAPajXUJa7WOI/j2/os3XKPPU7I9rfTmq7ngclQ7bo=; b=xh5htT2YctxpYp EFyjTyERiJOSiLOm5CN1NTysyiKm6JyvmWS8FjjVE7kX3omi0pBOcl6ceudZY/Lw136HraFLiRJkZ rSb8LcV9FN0DnyU89oExp6lsglU/hY+xIRxf/zQO0htoXNbAlDwJhvONvzRtqmC66aDRx1p8Zpw0W HyYtX+r+t2CVPhDonzb+QZdhqn7ux3xJbrCs7OzOHH1jIeb24FiePAcYE7QfLj/Ns8vYeSI6CheUd eQ8eIOxE/F202aBFR1CjIgGUUe0WyyNFuSFRHl5UW2sHJe49e3FNin4zf/HxBUaLZIf9/Cdx+2yvm EB1rSoCzW58/3pc2fQRA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oWHa5-003pZ1-2j; Thu, 08 Sep 2022 13:28:33 +0000 Received: from mail.8bytes.org ([85.214.250.239]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oWHa1-003pQR-Nu for linux-arm-kernel@lists.infradead.org; Thu, 08 Sep 2022 13:28:31 +0000 Received: from 8bytes.org (p4ff2bb62.dip0.t-ipconnect.de [79.242.187.98]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mail.8bytes.org (Postfix) with ESMTPSA id 6ACB624069C; Thu, 8 Sep 2022 15:28:23 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=8bytes.org; s=default; t=1662643704; bh=tDuhKm9wQfdx7sUd4hZrnBHJRGruWciJVuKdXgXOhg8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Nbzo8AaKCmLcJF6ywBTO/rjFGCww8jqPWoQ6WcBpBVILlVrrzm/ywTVSN6gtAJpvI A4WA5AxpHDg5Sd62NU3n5V/Vi1+huBSshzEAQAZS7xn++DhH0oznzPGAGwNcfBbTfq Twt1k1zJR6eHTY8BdmbO1Ww2bxQuZSP3YVyPip5R53rnIHglAbsB0bCYX0JzWlq5Om M3nAYqpIKCggsduzZcJAnKN/jYWRx4aw2vg7FWSxO/QqqKt7N7pAfFXxtOG8goJGLV xuiUyCTz0ghn5xX8vuVnC49wxhLLFEBrREVNPwdgKbdzr/ZwBoayTRYmgPniXvM4Pl wZdcX65MXNFqw== Date: Thu, 8 Sep 2022 15:28:22 +0200 From: Joerg Roedel To: Jason Gunthorpe Subject: Re: [PATCH v6 1/5] iommu: Return -EMEDIUMTYPE for incompatible domain and device/group Message-ID: References: <20220815181437.28127-1-nicolinc@nvidia.com> <20220815181437.28127-2-nicolinc@nvidia.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220908_062830_041010_8403BBBD X-CRM114-Status: GOOD ( 17.50 ) 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: , Cc: linux-s390@vger.kernel.org, marcan@marcan.st, mjrosato@linux.ibm.com, linux-kernel@vger.kernel.org, thierry.reding@gmail.com, will@kernel.org, alyssa@rosenzweig.io, jean-philippe@linaro.org, kvm@vger.kernel.org, zhang.lyra@gmail.com, jon@solid-run.com, jonathanh@nvidia.com, iommu@lists.linux.dev, Nicolin Chen , yangyingliang@huawei.com, orsonzhai@gmail.com, gerald.schaefer@linux.ibm.com, kevin.tian@intel.com, sven@svenpeter.dev, linux-arm-msm@vger.kernel.org, christophe.jaillet@wanadoo.fr, baolin.wang@linux.alibaba.com, thunder.leizhen@huawei.com, linux-tegra@vger.kernel.org, tglx@linutronix.de, virtualization@lists.linux-foundation.org, linux-arm-kernel@lists.infradead.org, dwmw2@infradead.org, cohuck@redhat.com, alex.williamson@redhat.com, shameerali.kolothum.thodi@huawei.com, robdclark@gmail.com, asahi@lists.linux.dev, suravee.suthikulpanit@amd.com, robin.murphy@arm.com, baolu.lu@linux.intel.com 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, Sep 07, 2022 at 02:10:33PM -0300, Jason Gunthorpe wrote: > Sure, rust has all sorts of nice things. But the kernel doesn't follow > rust idioms, and I don't think this is a great place to start > experimenting with them. It is actually a great place to start experimenting. The IOMMU interfaces are rather domain specific and if we get something wrong the damage is limited to a few callers. There are APIs much more exposed in the kernel which would be worse for that. But anyway, I am not insisting on it. > It has been 3 months since EMEDIUMTYPE was first proposed and 6 > iterations of the series, don't you think it is a bit late in the game > to try to experiment with rust error handling idioms? If I am not mistaken, I am the person who gets blamed when crappy IOMMU code is sent upstream. So it is also up to me to decide in which state and how close to merging a given patch series is an whether it is already 'late in the game'. > So, again, would you be happy with a simple > > #define IOMMU_EINCOMPATIBLE_DEVICE xx > > to make it less "re-using random error codes"? I am wondering if this can be solved by better defining what the return codes mean and adjust the call-back functions to match the definition. Something like: -ENODEV : Device not mapped my an IOMMU -EBUSY : Device attached and domain can not be changed -EINVAL : Device and domain are incompatible ... That would be much more intuitive than using something obscure like EMEDIUMTYPE. Regards, Joerg _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel