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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 240C0C04AB6 for ; Wed, 29 May 2019 02:41:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E79E621019 for ; Wed, 29 May 2019 02:41:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726548AbfE2ClB (ORCPT ); Tue, 28 May 2019 22:41:01 -0400 Received: from mga07.intel.com ([134.134.136.100]:34620 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725847AbfE2ClA (ORCPT ); Tue, 28 May 2019 22:41:00 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by orsmga105.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 28 May 2019 19:41:00 -0700 X-ExtLoop1: 1 Received: from allen-box.sh.intel.com (HELO [10.239.159.136]) ([10.239.159.136]) by orsmga004.jf.intel.com with ESMTP; 28 May 2019 19:40:57 -0700 Cc: baolu.lu@linux.intel.com, alex.williamson@redhat.com, shameerali.kolothum.thodi@huawei.com, jean-philippe.brucker@arm.com Subject: Re: [PATCH v5 7/7] iommu/vt-d: Differentiate relaxable and non relaxable RMRRs To: Eric Auger , eric.auger.pro@gmail.com, joro@8bytes.org, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, dwmw2@infradead.org, robin.murphy@arm.com References: <20190528115025.17194-1-eric.auger@redhat.com> <20190528115025.17194-8-eric.auger@redhat.com> From: Lu Baolu Message-ID: <13a77738-5e85-ea62-aab1-384c75bde8bd@linux.intel.com> Date: Wed, 29 May 2019 10:34:06 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20190528115025.17194-8-eric.auger@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 5/28/19 7:50 PM, Eric Auger wrote: > Now we have a new IOMMU_RESV_DIRECT_RELAXABLE reserved memory > region type, let's report USB and GFX RMRRs as relaxable ones. > > We introduce a new device_rmrr_is_relaxable() helper to check > whether the rmrr belongs to the relaxable category. > > This allows to have a finer reporting at IOMMU API level of > reserved memory regions. This will be exploitable by VFIO to > define the usable IOVA range and detect potential conflicts > between the guest physical address space and host reserved > regions. > > Signed-off-by: Eric Auger > > --- > > v3 -> v4: > - introduce device_rmrr_is_relaxable and reshuffle the comments > --- > drivers/iommu/intel-iommu.c | 55 +++++++++++++++++++++++++++---------- > 1 file changed, 40 insertions(+), 15 deletions(-) > > diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c > index 9302351818ab..01c82f848470 100644 > --- a/drivers/iommu/intel-iommu.c > +++ b/drivers/iommu/intel-iommu.c > @@ -2920,6 +2920,36 @@ static bool device_has_rmrr(struct device *dev) > return false; > } > > +/* > + * device_rmrr_is_relaxable - Test whether the RMRR of this device > + * is relaxable (ie. is allowed to be not enforced under some conditions) > + * > + * @dev: device handle > + * > + * We assume that PCI USB devices with RMRRs have them largely > + * for historical reasons and that the RMRR space is not actively used post > + * boot. This exclusion may change if vendors begin to abuse it. > + * > + * The same exception is made for graphics devices, with the requirement that > + * any use of the RMRR regions will be torn down before assigning the device > + * to a guest. > + * > + * Return: true if the RMRR is relaxable > + */ > +static bool device_rmrr_is_relaxable(struct device *dev) > +{ > + struct pci_dev *pdev; > + > + if (!dev_is_pci(dev)) > + return false; > + > + pdev = to_pci_dev(dev); > + if (IS_USB_DEVICE(pdev) || IS_GFX_DEVICE(pdev)) > + return true; > + else > + return false; > +} I know this is only code refactoring. But strictly speaking, the rmrr of any USB host device is ignorable only if quirk_usb_early_handoff() has been called. There, the control of USB host controller will be handed over from BIOS to OS and the corresponding SMI are disabled. This function is registered in drivers/usb/host/pci-quirks.c DECLARE_PCI_FIXUP_CLASS_FINAL(PCI_ANY_ID, PCI_ANY_ID, PCI_CLASS_SERIAL_USB, 8, quirk_usb_early_handoff); and only get compiled if CONFIG_USB_PCI is enabled. Hence, it's safer to say: +#ifdef CONFIG_USB_PCI + if (IS_USB_DEVICE(pdev)) + return true; +#endif /* CONFIG_USB_PCI */ I am okay if we keep this untouched and make this change within a separated patch. > + > /* > * There are a couple cases where we need to restrict the functionality of > * devices associated with RMRRs. The first is when evaluating a device for > @@ -2934,25 +2964,16 @@ static bool device_has_rmrr(struct device *dev) > * We therefore prevent devices associated with an RMRR from participating in > * the IOMMU API, which eliminates them from device assignment. > * > - * In both cases we assume that PCI USB devices with RMRRs have them largely > - * for historical reasons and that the RMRR space is not actively used post > - * boot. This exclusion may change if vendors begin to abuse it. > - * > - * The same exception is made for graphics devices, with the requirement that > - * any use of the RMRR regions will be torn down before assigning the device > - * to a guest. > + * In both cases, devices which have relaxable RMRRs are not concerned by this > + * restriction. See device_rmrr_is_relaxable comment. > */ > static bool device_is_rmrr_locked(struct device *dev) > { > if (!device_has_rmrr(dev)) > return false; > > - if (dev_is_pci(dev)) { > - struct pci_dev *pdev = to_pci_dev(dev); > - > - if (IS_USB_DEVICE(pdev) || IS_GFX_DEVICE(pdev)) > - return false; > - } > + if (device_rmrr_is_relaxable(dev)) > + return false; > > return true; > } > @@ -5494,6 +5515,7 @@ static void intel_iommu_get_resv_regions(struct device *device, > for_each_active_dev_scope(rmrr->devices, rmrr->devices_cnt, > i, i_dev) { > struct iommu_resv_region *resv; > + enum iommu_resv_type type; > size_t length; > > if (i_dev != device && > @@ -5501,9 +5523,12 @@ static void intel_iommu_get_resv_regions(struct device *device, > continue; > > length = rmrr->end_address - rmrr->base_address + 1; > + > + type = device_rmrr_is_relaxable(device) ? > + IOMMU_RESV_DIRECT_RELAXABLE : IOMMU_RESV_DIRECT; > + > resv = iommu_alloc_resv_region(rmrr->base_address, > - length, prot, > - IOMMU_RESV_DIRECT); > + length, prot, type); > if (!resv) > break; > > Other looks good to me. Reviewed-by: Lu Baolu Best regards, Baolu