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=-24.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1,USER_IN_DEF_DKIM_WL autolearn=unavailable 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 E1D4DC4320A for ; Tue, 3 Aug 2021 18:50:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CA1F260725 for ; Tue, 3 Aug 2021 18:50:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239277AbhHCSvF (ORCPT ); Tue, 3 Aug 2021 14:51:05 -0400 Received: from linux.microsoft.com ([13.77.154.182]:35834 "EHLO linux.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238195AbhHCSvC (ORCPT ); Tue, 3 Aug 2021 14:51:02 -0400 Received: from [192.168.1.115] (unknown [223.178.56.171]) by linux.microsoft.com (Postfix) with ESMTPSA id A5C7C208AB1E; Tue, 3 Aug 2021 11:50:46 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com A5C7C208AB1E DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1628016651; bh=yrbpSB1otFwR1Tu1Csab8DOioMdyKobhXI9/Ft52GG8=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=K4DGdAtk7yYMYs9z4xVcn10z4CVCrOraaCr75QTgoV4kqbgxkL71xW/EllD9G5cVD lW/HnybP6aDsZtXAxoQqSe21bWz6x7yYVV0km0Odz69sqgz2qhnpXXYHGtSU1K5m5e TPlyfD8ROLWzPNL/MBHwwYT+Lw6cv0iM2XWyOsVs= Subject: Re: [RFC v1 6/8] mshv: command line option to skip devices in PV-IOMMU To: Wei Liu , Linux on Hyper-V List Cc: virtualization@lists.linux-foundation.org, Linux Kernel List , Michael Kelley , Vineeth Pillai , Sunil Muthuswamy , Nuno Das Neves , pasha.tatashin@soleen.com, "K. Y. Srinivasan" , Haiyang Zhang , Stephen Hemminger , Dexuan Cui , Joerg Roedel , Will Deacon , "open list:IOMMU DRIVERS" References: <20210709114339.3467637-1-wei.liu@kernel.org> <20210709114339.3467637-7-wei.liu@kernel.org> From: Praveen Kumar Message-ID: <4a6918ea-e3e5-55c9-a12d-bee7261301fd@linux.microsoft.com> Date: Wed, 4 Aug 2021 00:20:42 +0530 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 MIME-Version: 1.0 In-Reply-To: <20210709114339.3467637-7-wei.liu@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09-07-2021 17:13, Wei Liu wrote: > Some devices may have been claimed by the hypervisor already. One such > example is a user can assign a NIC for debugging purpose. > > Ideally Linux should be able to tell retrieve that information, but > there is no way to do that yet. And designing that new mechanism is > going to take time. > > Provide a command line option for skipping devices. This is a stopgap > solution, so it is intentionally undocumented. Hopefully we can retire > it in the future. > > Signed-off-by: Wei Liu > --- > drivers/iommu/hyperv-iommu.c | 45 ++++++++++++++++++++++++++++++++++++ > 1 file changed, 45 insertions(+) > > diff --git a/drivers/iommu/hyperv-iommu.c b/drivers/iommu/hyperv-iommu.c > index 043dcff06511..353da5036387 100644 > --- a/drivers/iommu/hyperv-iommu.c > +++ b/drivers/iommu/hyperv-iommu.c > @@ -349,6 +349,16 @@ static const struct irq_domain_ops hyperv_root_ir_domain_ops = { > > #ifdef CONFIG_HYPERV_ROOT_PVIOMMU > > +/* The IOMMU will not claim these PCI devices. */ > +static char *pci_devs_to_skip; > +static int __init mshv_iommu_setup_skip(char *str) { > + pci_devs_to_skip = str; > + > + return 0; > +} > +/* mshv_iommu_skip=(SSSS:BB:DD.F)(SSSS:BB:DD.F) */ > +__setup("mshv_iommu_skip=", mshv_iommu_setup_skip); > + > /* DMA remapping support */ > struct hv_iommu_domain { > struct iommu_domain domain; > @@ -774,6 +784,41 @@ static struct iommu_device *hv_iommu_probe_device(struct device *dev) > if (!dev_is_pci(dev)) > return ERR_PTR(-ENODEV); > > + /* > + * Skip the PCI device specified in `pci_devs_to_skip`. This is a > + * temporary solution until we figure out a way to extract information > + * from the hypervisor what devices it is already using. > + */ > + if (pci_devs_to_skip && *pci_devs_to_skip) { > + int pos = 0; > + int parsed; > + int segment, bus, slot, func; > + struct pci_dev *pdev = to_pci_dev(dev); > + > + do { > + parsed = 0; > + > + sscanf(pci_devs_to_skip + pos, > + " (%x:%x:%x.%x) %n", > + &segment, &bus, &slot, &func, &parsed); > + > + if (parsed <= 0) > + break; > + > + if (pci_domain_nr(pdev->bus) == segment && > + pdev->bus->number == bus && > + PCI_SLOT(pdev->devfn) == slot && > + PCI_FUNC(pdev->devfn) == func) > + { > + dev_info(dev, "skipped by MSHV IOMMU\n"); > + return ERR_PTR(-ENODEV); > + } > + > + pos += parsed; > + > + } while (pci_devs_to_skip[pos]); Is there a possibility of pci_devs_to_skip + pos > sizeof(pci_devs_to_skip) and also a valid memory ? I would recommend to have a check of size as well before accessing the array content, just to be safer accessing any memory. > + } > + > vdev = kzalloc(sizeof(*vdev), GFP_KERNEL); > if (!vdev) > return ERR_PTR(-ENOMEM); > Regards, ~Praveen.