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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (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 E895DD3399E for ; Mon, 28 Oct 2024 16:50:36 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id B12DC10E510; Mon, 28 Oct 2024 16:50:36 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.b="pkI5kqhF"; dkim-atps=neutral Received: from nyc.source.kernel.org (nyc.source.kernel.org [147.75.193.91]) by gabe.freedesktop.org (Postfix) with ESMTPS id 717D410E510; Mon, 28 Oct 2024 16:50:35 +0000 (UTC) Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by nyc.source.kernel.org (Postfix) with ESMTP id 2D672A42A24; Mon, 28 Oct 2024 16:48:38 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4EDE5C4CEC7; Mon, 28 Oct 2024 16:50:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1730134233; bh=pMWXPesuF8JzrcGMxw6QNKDodBCUrn/XJfWhJqOIi/k=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=pkI5kqhFOL4hPrCJsofC2stUnspJjm6zGrt4OxWKdikOpGkx9D4nmXJx4C/VcJftq mE/iv5zzaJNUwYeH+8UGSMffivBEWZTqJMxCYzZ/9RFDHN5GNWtEv594Vs8OqFbqFC KvHQ6yoKZLdlFCOHSacP0wOL0jLUNBLI+n9RCK3vySApUKgsE0v84V1CxaSLOD4/et Cwwgtu2Hp9Ae77Da0pXA4iasz1yvXST1obtG2ttbSY9QAIHmWR8QgQNkU9M3rHvNrv o2jLzg4XdR80Z4O+4l7LuGU2IhXufItbN14hvCNEZt4ssz6b4CVBKdRM0a6Jlr6sbV SgNclE/avtfMQ== Date: Mon, 28 Oct 2024 11:50:31 -0500 From: Bjorn Helgaas To: =?utf-8?Q?Micha=C5=82?= Winiarski Cc: linux-pci@vger.kernel.org, intel-xe@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Bjorn Helgaas , Christian =?utf-8?B?S8O2bmln?= , Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= , Ilpo =?utf-8?B?SsOkcnZpbmVu?= , Rodrigo Vivi , Michal Wajdeczko , Lucas De Marchi , Thomas =?utf-8?Q?Hellstr=C3=B6m?= , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Matt Roper Subject: Re: [PATCH v4 6/7] PCI: Allow drivers to control VF BAR size Message-ID: <20241028165031.GA1106195@bhelgaas> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20241025215038.3125626-7-michal.winiarski@intel.com> X-BeenThere: intel-xe@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel Xe graphics driver List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-xe-bounces@lists.freedesktop.org Sender: "Intel-xe" On Fri, Oct 25, 2024 at 11:50:37PM +0200, Michał Winiarski wrote: > Drivers could leverage the fact that the VF BAR MMIO reservation is > created for total number of VFs supported by the device by resizing the > BAR to larger size when smaller number of VFs is enabled. > > Add a pci_iov_vf_bar_set_size() function to control the size and a > pci_iov_vf_bar_get_sizes() helper to get the VF BAR sizes that will > allow up to num_vfs to be successfully enabled with the current > underlying reservation size. > ... > + * pci_iov_vf_bar_get_sizes - get VF BAR sizes that allow to create up to num_vfs > + * @dev: the PCI device > + * @resno: the resource number > + * @num_vfs: number of VFs > + * > + * Get the sizes of a VF resizable BAR that can fit up to num_vfs within the > + * resource that reserves the MMIO space (originally up to total_VFs) the as > + * bitmask defined in the spec (bit 0=1MB, bit 19=512GB). This sentence doesn't quite parse; something is missing around "the as". I'm guessing you mean to say something about the return value being a bitmask of VF BAR sizes that can be accommodated if num_vfs are enabled? If so, maybe combine it with the following paragraph: > + * Returns 0 if BAR isn't resizable. > + * > + */ > +u32 pci_iov_vf_bar_get_sizes(struct pci_dev *dev, int resno, int num_vfs) > +{ > + resource_size_t size; > + u32 sizes; > + int i; > + > + sizes = pci_rebar_get_possible_sizes(dev, resno); > + if (!sizes) > + return 0; > + > + while (sizes > 0) { > + i = __fls(sizes); > + size = pci_rebar_size_to_bytes(i); > + > + if (size * num_vfs <= pci_resource_len(dev, resno)) > + break; > + > + sizes &= ~BIT(i); > + } > + > + return sizes; > +} > +EXPORT_SYMBOL_GPL(pci_iov_vf_bar_get_sizes);