From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lu Baolu Subject: Re: [PATCH 0/4] iommu/vt-d: Fix-up device-domain relationship by refactoring to use iommu group default domain. Date: Tue, 5 Mar 2019 14:05:26 +0800 Message-ID: References: <0F0C82BE-86E5-4BAC-938C-6F7629E18D27@arista.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <0F0C82BE-86E5-4BAC-938C-6F7629E18D27@arista.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: James Sewart , iommu@lists.linux-foundation.org Cc: baolu.lu@linux.intel.com, Tom Murphy , Dmitry Safonov , Jacob Pan , linux-kernel@vger.kernel.org List-Id: iommu@lists.linux-foundation.org Hi James, Very glad to see this. Thank you! On 3/4/19 11:41 PM, James Sewart wrote: > Hey, > > This patchset moves IOMMU_DOMAIN_DMA iommu domain management to iommu.c. > This avoids the use of find_or_alloc_domain whose domain assignment is > inconsistent with the iommu grouping as determined by pci_device_group. Is this a bug fix or an improvement? What's the real issue will it cause if we go without this patch set? Best regards, Lu Baolu > > Patch 3 permits domain type IOMMU_DOMAIN_DMA to be allocated via the > iommu_ops api, allowing the default_domain of an iommu group to be set in > iommu.c. This domain will be attached to every device that is brought up > with an iommu group, and the devices reserved regions will be mapped using > regions returned by get_resv_regions. > > In intel_iommu_domain_alloc we don’t know the IOMMU this domain will be > associated with so we defer full initialisation until > intel_iommu_attach_device. Currently iommu.c:iommu_group_add_device will > try to map a devices reserved regions before attaching the domain which > would cause issue if the domain is not fully initialised. This is > addressed in patch 1 by moving the mapping to after attaching. > > Patch 2 implements function apply_resv_region, used in > iommu_group_create_direct_mappings to mark the reserved regions as non > mappable for the dma_map_ops api. > > Patch 4 removes the domain lazy allocation logic. Before this patch the > lazy allocation logic would not be used as any domain allocated using > these paths would be replaced when attaching the group default domain. > Default domain allocation has been tested with and without this patch on > 4.19. > > Cheers, > James. > > James Sewart (4): > iommu: Move iommu_group_create_direct_mappings to after device_attach > iommu/vt-d: Implement apply_resv_region for reserving IOVA ranges > iommu/vt-d: Allow IOMMU_DOMAIN_DMA and IOMMU_DOMAIN_IDENTITY to be allocated > iommu/vt-d: Remove lazy allocation of domains > > drivers/iommu/intel-iommu.c | 329 ++++++++++++------------------------ > drivers/iommu/iommu.c | 4 +- > 2 files changed, 108 insertions(+), 225 deletions(-) >