Re: [PATCH 1/1] iommu/vt-d: Fix dmar pte read access not set error

[Jerry Snitselaar <jsnitsel@redhat.com>]

On Fri Dec 13 19, Lu Baolu wrote:
>Hi,
>
>On 12/13/19 8:30 AM, Jerry Snitselaar wrote:
>>On Thu Dec 12 19, Lu Baolu wrote:
>>>Hi,
>>>
>>>On 12/12/19 9:49 AM, Jerry Snitselaar wrote:
>>>>On Wed Dec 11 19, Lu Baolu wrote:
>>>>>If the default DMA domain of a group doesn't fit a device, it
>>>>>will still sit in the group but use a private identity domain.
>>>>>When map/unmap/iova_to_phys come through iommu API, the driver
>>>>>should still serve them, otherwise, other devices in the same
>>>>>group will be impacted. Since identity domain has been mapped
>>>>>with the whole available memory space and RMRRs, we don't need
>>>>>to worry about the impact on it.
>>>>>
>>>>>Link: https://www.spinics.net/lists/iommu/msg40416.html
>>>>>Cc: Jerry Snitselaar <jsnitsel@redhat.com>
>>>>>Reported-by: Jerry Snitselaar <jsnitsel@redhat.com>
>>>>>Fixes: 942067f1b6b97 ("iommu/vt-d: Identify default domains 
>>>>>replaced with private")
>>>>>Cc: stable@vger.kernel.org # v5.3+
>>>>>Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
>>>>
>>>>Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
>>>
>>>Can you please try this fix and check whether it can fix your problem?
>>>If it helps, do you mind adding a Tested-by?
>>>
>>>Best regards,
>>>baolu
>>>
>>
>>I'm testing with this patch, my patch that moves the direct mapping call,
>>and Alex's patch for the ISA bridge. It solved the 2 iommu mapping errors
>>I was seeing with default passthrough, I no longer see all the dmar pte
>>read access errors, and the system boots allowing me to login. I'm tracking
>>down 2 issues at the moment. With passthrough I see a problem with 01:00.4
>>that I mentioned in the earlier email:
>>
>>[   78.978573] uhci_hcd: USB Universal Host Controller Interface driver
>>[   78.980842] uhci_hcd 0000:01:00.4: UHCI Host Controller
>>[   78.982738] uhci_hcd 0000:01:00.4: new USB bus registered, 
>>assigned bus number 3
>>[   78.985222] uhci_hcd 0000:01:00.4: detected 8 ports
>>[   78.986907] uhci_hcd 0000:01:00.4: port count misdetected? 
>>forcing to 2 ports
>>[   78.989316] uhci_hcd 0000:01:00.4: irq 16, io base 0x00003c00
>>[   78.994634] uhci_hcd 0000:01:00.4: DMAR: 32bit DMA uses 
>>non-identity mapping
>>[   7 0000:01:00.4: unable to allocate consistent memory for frame list
>>[   79.499891] uhci_hcd 0000:01:00.4: startup error -16
>>[   79.501588] uhci_hcd 0000:01:00.4: USB bus 3 deregistered
>>[   79.503494] uhci_hcd 0000:01:00.4: init 0000:01:00.4 fail, -16
>>[   79.505497] uhci_hcd: probe of 0000:01:00.4 failed with error -16
>>
>>If I boot the system with iommu=nopt I see an iommu map failure due to
>>the prot check in __domain_mapping:
>>
>>[   40.940589] pci 0000:00:1f.0: iommu_group_add_device: calling 
>>iommu_group_create_direct_mappings
>>[   40.943558] pci 0000:00:1f.0: iommu_group_create_direct_mappings: 
>>iterating through mappings
>>[   40.946402] pci 0000:00:1f.0: iommu_group_create_direct_mappings: 
>>calling apply_resv_region
>>[   40.949184] pci 0000:00:1f.0: iommu_group_create_direct_mappings: 
>>entry type is direct
>>[   40.951819] DMAR: intel_iommu_map: enter
>>[   40.953128] DMAR: __domain_mapping: prot & 
>>(DMA_PTE_READ|DMA_PTE_WRITE) == 0
>>[   40.955486] DMAR: domain_mapping: __domain_mapping failed
>>[   40.957348] DMAR: intel_iommu_map: domain_pfn_mapping returned -22
>>[   40.959466] DMAR: intel_iommu_map: leave
>>[   40.959468] iommu: iommu_map: ops->map failed iova 0x0 pa 
>>0x0000000000000000 pgsize 0x1000
>>[   40.963511] pci 0000:00:1f.0: iommu_group_create_direct_mappings: 
>>iommu_map failed
>>[   40.966026] pci 0000:00:1f.0: iommu_group_create_direct_mappings: 
>>leaving func
>>[   40.968487] pci 0000:00:1f.0: iommu_group_add_device: calling 
>>__iommu_attach_device
>>[   40.971016] pci 0000:00:1f.0: Adding to iommu group 19
>>[   40.972731] pci 0000:00:1f.0: DMAR: domain->type is dma
>>
>>/sys/kernel/iommu_groups/19
>>[root@hp-dl388g8-07 19]# cat reserved_regions 0x0000000000000000 
>>0x0000000000ffffff direct
>>0x00000000bdf6e000 0x00000000bdf84fff direct
>>0x00000000fee00000 0x00000000feefffff msi
>>
>>00:1f.0 ISA bridge: Intel Corporation C600/X79 series chipset LPC 
>>Controller
>
>This seems to be another issue?
>
>Best regards,
>baolu

In intel_iommu_get_resv_regions this iommu_alloc_resv_region is called
with prot set to 0:

                 if ((pdev->class >> 8) == PCI_CLASS_BRIDGE_ISA) {
                         reg = iommu_alloc_resv_region(0, 1UL << 24, 0,
                                                       IOMMU_RESV_DIRECT_RELAXABLE);
                         if (reg)

I wonder if this is an issue with the region starting at 0x0 and this
bit in iommu_group_create_mappings:

			phys_addr = iommu_iova_to_phys(domain, addr);
			if (phys_addr)
				continue;

Off to stick in some more debugging statements.

Regards,
Jerry

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