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SubjectRe: [PATCH] iommu/intel-iommu: set as DUMMY_DEVICE_DOMAIN_INFO if no IOMMU
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Hi,

On 2020/2/7 15:32, Jian-Hong Pan wrote:
> Lu Baolu <baolu.lu@linux.intel.com> 於 2020年2月6日 週四 下午6:49寫道:
>>
>> 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?
>
> Yes.
>
>> 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?
>
> Good question! I have not think the change of DMAR for segment 0 and
> 1. But, I guess the answer is not. The hardware vendor will say
> Windows works fine ...
>
> The devices under segment 1 are fake devices produced by
> intel-nvme-remap mentioned here https://lkml.org/lkml/2020/2/5/139
>

Has this series been accepted?

> We are also curios about why VMD (drivers/pci/controller/vmd.c) works
> fine here. It also produces fake devices, but can use iommu
> correctly. Due to no VMD related machines on hand, it is hard to
> trace the flow. Could you please give us some clues?

Will this help here? https://www.spinics.net/lists/iommu/msg41300.html

Best regards,
baolu

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