Date:   Thu, 12 Dec 2019 20:16:33 -0700
From:   Jerry Snitselaar <jsnitsel@...hat.com>
To:     Lu Baolu <baolu.lu@...ux.intel.com>,
        Joerg Roedel <joro@...tes.org>,
        David Woodhouse <dwmw2@...radead.org>, ashok.raj@...el.com,
        jacob.jun.pan@...el.com, kevin.tian@...el.com,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org
Subject: Re: [PATCH 1/1] iommu/vt-d: Fix dmar pte read access not set error

On Thu Dec 12 19, Jerry Snitselaar wrote:
>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@...hat.com>
>>>>>>Reported-by: Jerry Snitselaar <jsnitsel@...hat.com>
>>>>>>Fixes: 942067f1b6b97 ("iommu/vt-d: Identify default domains 
>>>>>>replaced with private")
>>>>>>Cc: stable@...r.kernel.org # v5.3+
>>>>>>Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
>>>>>
>>>>>Reviewed-by: Jerry Snitselaar <jsnitsel@...hat.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@...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)
>

Looking at the older code for the ISA bridge it looks like it called
iommu_prepare_identity_map -> domain_prepare_identity_map ->
iommu_domain_identity_map -> and finally __domain_mapping with DMA_PTE_READ|DMA_PTE_WRITE?

>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;

Disregard this

>
>Off to stick in some more debugging statements.
>
>Regards,
>Jerry
>
>>_______________________________________________
>>iommu mailing list
>>iommu@...ts.linux-foundation.org
>>https://lists.linuxfoundation.org/mailman/listinfo/iommu

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