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[142.68.128.5]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-6cbe85b7597sm16987756d6.42.2024.10.11.09.27.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 11 Oct 2024 09:27:04 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.95) (envelope-from ) id 1szITn-007dB9-Kl; Fri, 11 Oct 2024 13:27:03 -0300 Date: Fri, 11 Oct 2024 13:27:03 -0300 From: Jason Gunthorpe To: Lu Baolu Cc: iommu@lists.linux.dev, Joerg Roedel , Will Deacon , Robin Murphy , Kevin Tian , Yi Liu , Vasant Hegde , linux-kernel@vger.kernel.org Subject: Re: [PATCH 3/7] iommu/vt-d: Enhance compatibility check for paging domain attach Message-ID: <20241011162703.GL762027@ziepe.ca> References: <20241011042722.73930-1-baolu.lu@linux.intel.com> <20241011042722.73930-4-baolu.lu@linux.intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241011042722.73930-4-baolu.lu@linux.intel.com> On Fri, Oct 11, 2024 at 12:27:18PM +0800, Lu Baolu wrote: > @@ -1623,27 +1623,15 @@ static int domain_context_mapping_one(struct dmar_domain *domain, > > copied_context_tear_down(iommu, context, bus, devfn); > context_clear_entry(context); > - > context_set_domain_id(context, did); > > - /* > - * Skip top levels of page tables for iommu which has > - * less agaw than default. Unnecessary for PT mode. > - */ > - for (agaw = domain->agaw; agaw > iommu->agaw; agaw--) { > - ret = -ENOMEM; > - pgd = phys_to_virt(dma_pte_addr(pgd)); > - if (!dma_pte_present(pgd)) > - goto out_unlock; > - } Yikes, this is nasty racy stuff, glad to see it go But should the agaw stuff be in its own patch? > @@ -3506,27 +3483,26 @@ int prepare_domain_attach_device(struct iommu_domain *domain, > if (domain->dirty_ops && !ssads_supported(iommu)) > return -EINVAL; > > - /* check if this iommu agaw is sufficient for max mapped address */ > - addr_width = agaw_to_width(iommu->agaw); > - if (addr_width > cap_mgaw(iommu->cap)) > - addr_width = cap_mgaw(iommu->cap); > - > - if (dmar_domain->max_addr > (1LL << addr_width)) > + if (dmar_domain->iommu_coherency != > + iommu_paging_structure_coherency(iommu)) > return -EINVAL; > - dmar_domain->gaw = addr_width; > - > - /* > - * Knock out extra levels of page tables if necessary > - */ > - while (iommu->agaw < dmar_domain->agaw) { > - struct dma_pte *pte; > - > - pte = dmar_domain->pgd; > - if (dma_pte_present(pte)) { > - dmar_domain->pgd = phys_to_virt(dma_pte_addr(pte)); > - iommu_free_page(pte); > - } > - dmar_domain->agaw--; > + > + if (domain->type & __IOMMU_DOMAIN_PAGING) { It looks like this entire function is already never called for anything but paging? The only three callers are: .default_domain_ops = &(const struct iommu_domain_ops) { .attach_dev = intel_iommu_attach_device, .set_dev_pasid = intel_iommu_set_dev_pasid, and static const struct iommu_domain_ops intel_nested_domain_ops = { .attach_dev = intel_nested_attach_dev, And none of those cases can be anything except a paging domain by definition. So this if should go away, or be turned into a WARN_ON. Jason