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Subject: Re: [PATCH] iommu/intel-iommu: set as DUMMY_DEVICE_DOMAIN_INFO if no
 IOMMU
To:     Jian-Hong Pan <jian-hong@endlessm.com>
Cc:     David Woodhouse <dwmw2@infradead.org>,
        Joerg Roedel <joro@8bytes.org>,
        iommu@lists.linux-foundation.org,
        Linux Kernel <linux-kernel@vger.kernel.org>,
        Linux Upstreaming Team <linux@endlessm.com>,
        "Raj, Ashok" <ashok.raj@intel.com>,
        "jacob.jun.pan@linux.intel.com" <jacob.jun.pan@linux.intel.com>,
        "Tian, Kevin" <kevin.tian@intel.com>
References: <20200203091009.196658-1-jian-hong@endlessm.com>
 <aab0948d-c6a3-baa1-7343-f18c936d662d@linux.intel.com>
 <CAPpJ_edkkWm0DYHB3U8nQPv=z_o-aV4V7RDMuLTXL5N1H6ZYrA@mail.gmail.com>
 <948da337-128f-22ae-7b2e-730b4b8da446@linux.intel.com>
 <CAPpJ_ecM0oCUjYLbG+uTprRk0=OTUBTxZc-d2BGBRDSYWk4uSQ@mail.gmail.com>
From:   Lu Baolu <baolu.lu@linux.intel.com>
Message-ID: <c8d89c4f-1347-8b9d-0486-a29dd081f26c@linux.intel.com>
Date:   Thu, 6 Feb 2020 18:49:52 +0800
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Hi,

On 2020/2/5 18:06, Jian-Hong Pan wrote:
> Lu Baolu <baolu.lu@linux.intel.com> 於 2020年2月5日 週三 上午9:28寫道：
>>
>> Hi,
>>
>> On 2020/2/4 17:25, Jian-Hong Pan wrote:
>>> Lu Baolu <baolu.lu@linux.intel.com> 於 2020年2月4日 週二 下午2:11寫道：
>>>>
>>>> Hi,
>>>>
>>>> On 2020/2/3 17:10, Jian-Hong Pan wrote:
>>>>> If the device has no IOMMU, it still invokes iommu_need_mapping during
>>>>> intel_alloc_coherent. However, iommu_need_mapping can only check the
>>>>> device is DUMMY_DEVICE_DOMAIN_INFO or not. This patch marks the device
>>>>> is a DUMMY_DEVICE_DOMAIN_INFO if the device has no IOMMU.
>>>>>
>>>>> Signed-off-by: Jian-Hong Pan <jian-hong@endlessm.com>
>>>>> ---
>>>>>     drivers/iommu/intel-iommu.c | 4 +++-
>>>>>     1 file changed, 3 insertions(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
>>>>> index 35a4a3abedc6..878bc986a015 100644
>>>>> --- a/drivers/iommu/intel-iommu.c
>>>>> +++ b/drivers/iommu/intel-iommu.c
>>>>> @@ -5612,8 +5612,10 @@ static int intel_iommu_add_device(struct device *dev)
>>>>>         int ret;
>>>>>
>>>>>         iommu = device_to_iommu(dev, &bus, &devfn);
>>>>> -     if (!iommu)
>>>>> +     if (!iommu) {
>>>>> +             dev->archdata.iommu = DUMMY_DEVICE_DOMAIN_INFO;
>>>>
>>>> Is this a DMA capable device?
>>>
>>> Do you mean is the device in DMA Remapping table?
>>> Dump DMAR from ACPI table.  The device is not in the table.
>>> So, it does not support DMAR, Intel IOMMU.
>>>
>>> Or, should device_to_iommu be invoked in iommu_need_mapping to check
>>> IOMMU feature again?
>>>
>>
>> Normally intel_iommu_add_device() should only be called for PCI devices
>> and APCI name space devices (reported in ACPI/DMAR table). In both
>> cases, device_to_iommu() should always return a corresponding iommu. I
>> just tried to understand why it failed for your case.
> 
> We found all of the DMAR featured devices's PCI Segment Number is *0000*.
> But the devices locating under segment/domain *0001* hit the issue,
> until the patch is applied.
> 
> Because of different segment numbers, none of iommu will be matched by
> for_each_active_iommu(iommu, drhd) loop in function device_to_iommu()
> and it will return NULL.  So, intel_iommu_add_device() returns no
> device.
> 
> I can share the DMAR:
> /*
>   * Intel ACPI Component Architecture
>   * AML/ASL+ Disassembler version 20200110 (64-bit version)
>   * Copyright (c) 2000 - 2020 Intel Corporation
>   *
>   * Disassembly of dmar.dat, Wed Jan 22 11:41:50 2020
>   *
>   * ACPI Data Table [DMAR]
>   *
>   * Format: [HexOffset DecimalOffset ByteLength]  FieldName : FieldValue
>   */
> 
> [000h 0000   4]                    Signature : "DMAR"    [DMA Remapping table]
> [004h 0004   4]                 Table Length : 000000A8
> [008h 0008   1]                     Revision : 01
> [009h 0009   1]                     Checksum : 5E
> [00Ah 0010   6]                       Oem ID : "INTEL "
> [010h 0016   8]                 Oem Table ID : "EDK2    "
> [018h 0024   4]                 Oem Revision : 00000002
> [01Ch 0028   4]              Asl Compiler ID : "    "
> [020h 0032   4]        Asl Compiler Revision : 01000013
> 
> [024h 0036   1]           Host Address Width : 26
> [025h 0037   1]                        Flags : 05
> [026h 0038  10]                     Reserved : 00 00 00 00 00 00 00 00 00 00
> 
> [030h 0048   2]                Subtable Type : 0000 [Hardware Unit Definition]
> [032h 0050   2]                       Length : 0018
> 
> [034h 0052   1]                        Flags : 00
> [035h 0053   1]                     Reserved : 00
> [036h 0054   2]           PCI Segment Number : 0000
> [038h 0056   8]        Register Base Address : 00000000FED90000
> 
> [040h 0064   1]            Device Scope Type : 01 [PCI Endpoint Device]
> [041h 0065   1]                 Entry Length : 08
> [042h 0066   2]                     Reserved : 0000
> [044h 0068   1]               Enumeration ID : 00
> [045h 0069   1]               PCI Bus Number : 00
> 
> [046h 0070   2]                     PCI Path : 02,00
> 
> 
> [048h 0072   2]                Subtable Type : 0000 [Hardware Unit Definition]
> [04Ah 0074   2]                       Length : 0020
> 
> [04Ch 0076   1]                        Flags : 01
> [04Dh 0077   1]                     Reserved : 00
> [04Eh 0078   2]           PCI Segment Number : 0000
> [050h 0080   8]        Register Base Address : 00000000FED91000
> 
> [058h 0088   1]            Device Scope Type : 03 [IOAPIC Device]
> [059h 0089   1]                 Entry Length : 08
> [05Ah 0090   2]                     Reserved : 0000
> [05Ch 0092   1]               Enumeration ID : 02
> [05Dh 0093   1]               PCI Bus Number : 00
> 
> [05Eh 0094   2]                     PCI Path : 1E,07
> 
> 
> [060h 0096   1]            Device Scope Type : 04 [Message-capable HPET Device]
> [061h 0097   1]                 Entry Length : 08
> [062h 0098   2]                     Reserved : 0000
> [064h 0100   1]               Enumeration ID : 00
> [065h 0101   1]               PCI Bus Number : 00
> 
> [066h 0102   2]                     PCI Path : 1E,06
> 
> 
> [068h 0104   2]                Subtable Type : 0001 [Reserved Memory Region]
> [06Ah 0106   2]                       Length : 0020
> 
> [06Ch 0108   2]                     Reserved : 0000
> [06Eh 0110   2]           PCI Segment Number : 0000
> [070h 0112   8]                 Base Address : 000000006F58B000
> [078h 0120   8]          End Address (limit) : 000000006F7D4FFF
> 
> [080h 0128   1]            Device Scope Type : 01 [PCI Endpoint Device]
> [081h 0129   1]                 Entry Length : 08
> [082h 0130   2]                     Reserved : 0000
> [084h 0132   1]               Enumeration ID : 00
> [085h 0133   1]               PCI Bus Number : 00
> 
> [086h 0134   2]                     PCI Path : 14,00
> 
> 
> [088h 0136   2]                Subtable Type : 0001 [Reserved Memory Region]
> [08Ah 0138   2]                       Length : 0020
> 
> [08Ch 0140   2]                     Reserved : 0000
> [08Eh 0142   2]           PCI Segment Number : 0000
> [090h 0144   8]                 Base Address : 0000000079800000
> [098h 0152   8]          End Address (limit) : 000000007DFFFFFF
> 
> [0A0h 0160   1]            Device Scope Type : 01 [PCI Endpoint Device]
> [0A1h 0161   1]                 Entry Length : 08
> [0A2h 0162   2]                     Reserved : 0000
> [0A4h 0164   1]               Enumeration ID : 00
> [0A5h 0165   1]               PCI Bus Number : 00
> 
> [0A6h 0166   2]                     PCI Path : 02,00
> 
> 
> Raw Table Data: Length 168 (0xA8)
> 
>      0000: 44 4D 41 52 A8 00 00 00 01 5E 49 4E 54 45 4C 20  // DMAR.....^INTEL
>      0010: 45 44 4B 32 20 20 20 20 02 00 00 00 20 20 20 20  // EDK2    ....
>      0020: 13 00 00 01 26 05 00 00 00 00 00 00 00 00 00 00  // ....&...........
>      0030: 00 00 18 00 00 00 00 00 00 00 D9 FE 00 00 00 00  // ................
>      0040: 01 08 00 00 00 00 02 00 00 00 20 00 01 00 00 00  // .......... .....
>      0050: 00 10 D9 FE 00 00 00 00 03 08 00 00 02 00 1E 07  // ................
>      0060: 04 08 00 00 00 00 1E 06 01 00 20 00 00 00 00 00  // .......... .....
>      0070: 00 B0 58 6F 00 00 00 00 FF 4F 7D 6F 00 00 00 00  // ..Xo.....O}o....
>      0080: 01 08 00 00 00 00 14 00 01 00 20 00 00 00 00 00  // .......... .....
>      0090: 00 00 80 79 00 00 00 00 FF FF FF 7D 00 00 00 00  // ...y.......}....
>      00A0: 01 08 00 00 00 00 02 00                          // ........
> 
> Here is the lspci:
> 0000:00:00.0 Host bridge: Intel Corporation Device 9b61 (rev 0c)
> 0000:00:02.0 VGA compatible controller: Intel Corporation Device 9b41 (rev 02)
> 0000:00:04.0 Signal processing controller: Intel Corporation Skylake
> Processor Thermal Subsystem (rev 0c)
> 0000:00:08.0 System peripheral: Intel Corporation Skylake Gaussian Mixture Model
> 0000:00:12.0 Signal processing controller: Intel Corporation Device 02f9
> 0000:00:13.0 Serial controller: Intel Corporation Device 02fc
> 0000:00:14.0 USB controller: Intel Corporation Device 02ed
> 0000:00:14.2 RAM memory: Intel Corporation Device 02ef
> 0000:00:14.3 Network controller: Intel Corporation Device 02f0
> 0000:00:15.0 Serial bus controller [0c80]: Intel Corporation Device 02e8
> 0000:00:15.1 Serial bus controller [0c80]: Intel Corporation Device 02e9
> 0000:00:15.2 Serial bus controller [0c80]: Intel Corporation Device 02ea
> 0000:00:16.0 Communication controller: Intel Corporation Device 02e0
> 0000:00:17.0 RAID bus controller: Intel Corporation Device 02d7
> 0000:00:1c.0 PCI bridge: Intel Corporation Device 02b8 (rev f0)
> 0000:00:1e.0 Communication controller: Intel Corporation Device 02a8
> 0000:00:1e.2 Serial bus controller [0c80]: Intel Corporation Device 02aa
> 0000:00:1f.0 ISA bridge: Intel Corporation Device 0284
> 0000:00:1f.3 Audio device: Intel Corporation Device 02c8
> 0000:00:1f.4 SMBus: Intel Corporation Device 02a3
> 0000:00:1f.5 Serial bus controller [0c80]: Intel Corporation Device 02a4
> 0000:00:1f.6 Ethernet controller: Intel Corporation Device 0d4f
> 0000:01:00.0 PCI bridge: Intel Corporation JHL7540 Thunderbolt 3
> Bridge [Titan Ridge 4C 2018] (rev 06)
> 0000:02:00.0 PCI bridge: Intel Corporation JHL7540 Thunderbolt 3
> Bridge [Titan Ridge 4C 2018] (rev 06)
> 0000:02:01.0 PCI bridge: Intel Corporation JHL7540 Thunderbolt 3
> Bridge [Titan Ridge 4C 2018] (rev 06)
> 0000:02:02.0 PCI bridge: Intel Corporation JHL7540 Thunderbolt 3
> Bridge [Titan Ridge 4C 2018] (rev 06)
> 0000:02:04.0 PCI bridge: Intel Corporation JHL7540 Thunderbolt 3
> Bridge [Titan Ridge 4C 2018] (rev 06)
> 0000:03:00.0 System peripheral: Intel Corporation JHL7540 Thunderbolt
> 3 NHI [Titan Ridge 4C 2018] (rev 06)
> 0000:37:00.0 USB controller: Intel Corporation JHL7540 Thunderbolt 3
> USB Controller [Titan Ridge 4C 2018] (rev 06)
> 0001:00:00.0 SATA controller: Intel Corporation Device 02d7
> 0001:00:01.0 Non-Volatile memory controller: Intel Corporation Device 0000
> 0001:00:02.0 Non-Volatile memory controller: Intel Corporation Device 0000
>

So devices are sitting in PCI segment 1, while ACPI/DMAR only reports
IOMMU units for PCI segment 0. Do I understand it right?

Is it possible that hardware supports DMAR for both PCI segment 0 and 1,
but the firmware doesn't reports those for PCI segement 1?

> Best regards,
> Jian-Hong Pan
> 

Best regards,
baolu