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 X-Spam-Level: X-Spam-Status: No, score=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A3FE4C8300A for ; Thu, 30 Apr 2020 10:14:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7F08E214D8 for ; Thu, 30 Apr 2020 10:14:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588241679; bh=K4iRN3zCPNFjbTseot6WcbvyRWpaRNNyZ8e0DoLGw0E=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=rnvhQH/wchGyrLlmIJzUolO9DwUQeXu/68quu904LjF7OEFcLoN01He/c7Cu6iB57 0OHcwtSF9Th7NddiN/0cHZ144JZj49/g5n94hB1uJgiMWpcdn3mSA0e0tWQotXG8x1 7YVR4Xps09nN+UyYkZQJUXyU1J7dR0jiZ/9J3ZO8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726781AbgD3KOi (ORCPT ); Thu, 30 Apr 2020 06:14:38 -0400 Received: from mail.kernel.org ([198.145.29.99]:46132 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725280AbgD3KOi (ORCPT ); Thu, 30 Apr 2020 06:14:38 -0400 Received: from willie-the-truck (236.31.169.217.in-addr.arpa [217.169.31.236]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 546C52082E; Thu, 30 Apr 2020 10:14:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588241677; bh=K4iRN3zCPNFjbTseot6WcbvyRWpaRNNyZ8e0DoLGw0E=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=JvlDRD0fualhnU0GtkqaCGYeK0Ta5RV7QlJMm+JXxK6sJpn+Ba3M4ZH+1i92mJL0x heHHfzv8MWGQl/ku3fbX8+JeRaDczFuoMJh77a7aya9Z2AA2yQdeG6kk2+w4pu21MY nx67itkvi/2CXKxGbdHb5la8yWUNEL0Nqkcfe3pc= Date: Thu, 30 Apr 2020 11:14:32 +0100 From: Will Deacon To: Srivatsa Vaddagiri Cc: konrad.wilk@oracle.com, mst@redhat.com, jasowang@redhat.com, jan.kiszka@siemens.com, stefano.stabellini@xilinx.com, iommu@lists.linux-foundation.org, virtualization@lists.linux-foundation.org, virtio-dev@lists.oasis-open.org, tsoni@codeaurora.org, pratikp@codeaurora.org, christoffer.dall@arm.com, alex.bennee@linaro.org, linux-kernel@vger.kernel.org Subject: Re: [RFC/PATCH 1/1] virtio: Introduce MMIO ops Message-ID: <20200430101431.GD19932@willie-the-truck> References: <1588240976-10213-1-git-send-email-vatsa@codeaurora.org> <1588240976-10213-2-git-send-email-vatsa@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1588240976-10213-2-git-send-email-vatsa@codeaurora.org> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 30, 2020 at 03:32:56PM +0530, Srivatsa Vaddagiri wrote: > Some hypervisors may not support MMIO transport i.e trap config > space access and have it be handled by backend driver. They may > allow other ways to interact with backend such as message-queue > or doorbell API. This patch allows for hypervisor specific > methods for config space IO. > > Signed-off-by: Srivatsa Vaddagiri > --- > drivers/virtio/virtio_mmio.c | 131 ++++++++++++++++++++++++++----------------- > include/linux/virtio.h | 14 +++++ > 2 files changed, 94 insertions(+), 51 deletions(-) > > diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c > index 97d5725..69bfa35 100644 > --- a/drivers/virtio/virtio_mmio.c > +++ b/drivers/virtio/virtio_mmio.c > @@ -100,7 +100,35 @@ struct virtio_mmio_vq_info { > struct list_head node; > }; > > +#ifdef CONFIG_VIRTIO_MMIO_OPS > > +static struct virtio_mmio_ops *mmio_ops; > + > +#define virtio_readb(a) mmio_ops->mmio_readl((a)) > +#define virtio_readw(a) mmio_ops->mmio_readl((a)) > +#define virtio_readl(a) mmio_ops->mmio_readl((a)) > +#define virtio_writeb(val, a) mmio_ops->mmio_writeb((val), (a)) > +#define virtio_writew(val, a) mmio_ops->mmio_writew((val), (a)) > +#define virtio_writel(val, a) mmio_ops->mmio_writel((val), (a)) How exactly are these ops hooked up? I'm envisaging something like: ops = spec_compliant_ops; [...] if (firmware_says_hypervisor_is_buggy()) ops = magic_qcom_ops; am I wrong? > +int register_virtio_mmio_ops(struct virtio_mmio_ops *ops) > +{ > + pr_info("Registered %s as mmio ops\n", ops->name); > + mmio_ops = ops; Not looking good, and really defeats the point of standardising this stuff imo. Will