From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8414731AA9B; Wed, 4 Mar 2026 14:26:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772634365; cv=none; b=HPMK2OaT7X3eWO5QY8dsgiuE2Vrs7426Eui+gwJl8eDTpGHrJBgVZ1ty+LRC75kUW1HQ0cqEHSQ1lF+83ia1RUAvtvuj14kSH4i2XxMSZqDCrndUU4/DuP9/pr/5oKCZALWVHsVZJJcHYUwVxViBdFR99iLOozxWcGc5989HhCo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772634365; c=relaxed/simple; bh=B0weNWDunmwVDkkQkN0kc7eG+tPkHSnvIyKW9SWUWPk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=aUurjURWIww4u9oj/kGcb9ryyjEkGzLnwRK3PyyOT5MRoM+jtjN93+j5twVSqVlO2ZYPc1mGh5I+1M0m8Kcl5xhXcFPkmnosdIKvpNetlhN97C2MGpCMGWkTUd9w+GsVbAxgQhxaIEIhVvthW9V79Mna2fBwt4qnrAQyR49dLYg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Ts/0Flsu; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Ts/0Flsu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 833ACC2BC87; Wed, 4 Mar 2026 14:26:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772634365; bh=B0weNWDunmwVDkkQkN0kc7eG+tPkHSnvIyKW9SWUWPk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Ts/0Flsu+WenzEZfA5RIGH5FOlyHpWYzSgcefBgKg2f19RaSYz+irtf4VdJbC766a NEaEpQ4umSV40OOs9ljryMEiSfaxm3WaBTUH3UGZdOvowqt/RrlEXVEAKUI6C31Gvf sG/yB38kxV7mnWG2tWKaBWl+zjobjnciujPIucg+/jacQpHmpX7sP2g5nZzJTR2aZw bKWY102ePDXk+dqRHGD/xD9P0Lzhe933nURcNLqi+A56D/2L2FMtcX/pA3iitdI5HO WVnC3yjobyeiqlz2mpolNYTWQuQHio4sAY+ArQ4J4bALd5gkWoYuv152zQoKTasSQM 3hHcgssibybRg== Date: Wed, 4 Mar 2026 16:26:00 +0200 From: Leon Romanovsky To: Jason Gunthorpe Cc: Peter Colberg , Danilo Krummrich , Bjorn Helgaas , Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= , Miguel Ojeda , Alex Gaynor , Gary Guo , =?iso-8859-1?Q?Bj=F6rn?= Roy Baron , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Abdiel Janulgue , Daniel Almeida , Robin Murphy , Greg Kroah-Hartman , Dave Ertman , Ira Weiny , David Airlie , Simona Vetter , Jonathan Corbet , Xu Yilun , Tom Rix , Moritz Fischer , "Rafael J. Wysocki" , Boqun Feng , linux-pci@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, Alexandre Courbot , Alistair Popple , Joel Fernandes , John Hubbard , Zhi Wang , nouveau@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-doc@vger.kernel.org, linux-fpga@vger.kernel.org, driver-core@lists.linux.dev Subject: Re: [PATCH v3 00/10] rust: pci: add abstractions for SR-IOV capability Message-ID: <20260304142600.GB12611@unreal> References: <20260303-rust-pci-sriov-v3-0-4443c35f0c88@redhat.com> <20260304084750.GW12611@unreal> <20260304141852.GF964116@ziepe.ca> Precedence: bulk X-Mailing-List: driver-core@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20260304141852.GF964116@ziepe.ca> On Wed, Mar 04, 2026 at 10:18:52AM -0400, Jason Gunthorpe wrote: > On Wed, Mar 04, 2026 at 10:47:50AM +0200, Leon Romanovsky wrote: > > On Tue, Mar 03, 2026 at 04:15:20PM -0500, Peter Colberg wrote: > > > Add Rust abstractions for the Single Root I/O Virtualization (SR-IOV) > > > capability of a PCI device. Provide a minimal set of wrappers for the > > > SR-IOV C API to enable and disable SR-IOV for a device, and query if > > > a PCI device is a Physical Function (PF) or Virtual Function (VF). > > > > <...> > > > > > For PF drivers written in C, disabling SR-IOV on remove() may be opted > > > into by setting the flag managed_sriov in the pci_driver structure. For > > > PF drivers written in Rust, disabling SR-IOV on unbind() is mandatory. > > > > Why? Could you explain the rationale behind this difference between C and > > Rust? Let me remind you that SR‑IOV devices which do not disable VFs do so > > for a practical and well‑established reason: maximizing hardware > > utilization. > > Personally I think drivers doing this are wrong. That such a driver > bug was allowed to become UAPI is pretty bad. The rust approach is > better. We already had this discussion. I see this as a perfectly valid use-case. Thanks > > Jason 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 EC2AEEF8FEE for ; Wed, 4 Mar 2026 14:26:10 +0000 (UTC) Received: from kara.freedesktop.org (unknown [131.252.210.166]) by gabe.freedesktop.org (Postfix) with ESMTPS id C5A5110EA2A; Wed, 4 Mar 2026 14:26:10 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.b="Ts/0Flsu"; dkim-atps=neutral Received: from kara.freedesktop.org (localhost [127.0.0.1]) by kara.freedesktop.org (Postfix) with ESMTP id 8179D44E38; Wed, 4 Mar 2026 14:15:50 +0000 (UTC) ARC-Seal: i=1; cv=none; 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a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772634365; bh=B0weNWDunmwVDkkQkN0kc7eG+tPkHSnvIyKW9SWUWPk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Ts/0Flsu+WenzEZfA5RIGH5FOlyHpWYzSgcefBgKg2f19RaSYz+irtf4VdJbC766a NEaEpQ4umSV40OOs9ljryMEiSfaxm3WaBTUH3UGZdOvowqt/RrlEXVEAKUI6C31Gvf sG/yB38kxV7mnWG2tWKaBWl+zjobjnciujPIucg+/jacQpHmpX7sP2g5nZzJTR2aZw bKWY102ePDXk+dqRHGD/xD9P0Lzhe933nURcNLqi+A56D/2L2FMtcX/pA3iitdI5HO WVnC3yjobyeiqlz2mpolNYTWQuQHio4sAY+ArQ4J4bALd5gkWoYuv152zQoKTasSQM 3hHcgssibybRg== Date: Wed, 4 Mar 2026 16:26:00 +0200 From: Leon Romanovsky To: Jason Gunthorpe Subject: Re: [PATCH v3 00/10] rust: pci: add abstractions for SR-IOV capability Message-ID: <20260304142600.GB12611@unreal> References: <20260303-rust-pci-sriov-v3-0-4443c35f0c88@redhat.com> <20260304084750.GW12611@unreal> <20260304141852.GF964116@ziepe.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20260304141852.GF964116@ziepe.ca> Message-ID-Hash: 7JMI5SCA5AAECLR445EK4F7WL3ASUF5C X-Message-ID-Hash: 7JMI5SCA5AAECLR445EK4F7WL3ASUF5C X-MailFrom: leon@kernel.org X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: Danilo Krummrich , Bjorn Helgaas , Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= , Miguel Ojeda , Alex Gaynor , Gary Guo , =?iso-8859-1?Q?Bj=F6rn?= Roy Baron , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Abdiel Janulgue , Daniel Almeida , Robin Murphy , Greg Kroah-Hartman , Dave Ertman , Ira Weiny , Simona Vetter , Jonathan Corbet , Xu Yilun , Tom Rix , Moritz Fischer , "Rafael J. Wysocki" , Boqun Feng , linux-pci@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, Alexandre Courbot , Alistair Popple , Joel Fernandes , Zhi Wang , nouveau@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-doc@vger.kernel.org, linux-fpga@vger.kernel.org, driver-core@lists.linux.dev X-Mailman-Version: 3.3.8 Precedence: list List-Id: Nouveau development list Archived-At: Archived-At: List-Archive: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: On Wed, Mar 04, 2026 at 10:18:52AM -0400, Jason Gunthorpe wrote: > On Wed, Mar 04, 2026 at 10:47:50AM +0200, Leon Romanovsky wrote: > > On Tue, Mar 03, 2026 at 04:15:20PM -0500, Peter Colberg wrote: > > > Add Rust abstractions for the Single Root I/O Virtualization (SR-IOV) > > > capability of a PCI device. Provide a minimal set of wrappers for the > > > SR-IOV C API to enable and disable SR-IOV for a device, and query if > > > a PCI device is a Physical Function (PF) or Virtual Function (VF). > > > > <...> > > > > > For PF drivers written in C, disabling SR-IOV on remove() may be opted > > > into by setting the flag managed_sriov in the pci_driver structure. For > > > PF drivers written in Rust, disabling SR-IOV on unbind() is mandatory. > > > > Why? Could you explain the rationale behind this difference between C and > > Rust? Let me remind you that SR‑IOV devices which do not disable VFs do so > > for a practical and well‑established reason: maximizing hardware > > utilization. > > Personally I think drivers doing this are wrong. That such a driver > bug was allowed to become UAPI is pretty bad. The rust approach is > better. We already had this discussion. I see this as a perfectly valid use-case. Thanks > > Jason