[RFCv2 PATCH 14/36] iommu/arm-smmu-v3: Add support for Substream IDs

[Yisheng Xie]

Hi Jean,

On 2017/11/3 1:02, Shameerali Kolothum Thodi wrote:
> 
> 
>> -----Original Message-----
>> From: Jean-Philippe Brucker [mailto:Jean-Philippe.Brucker at arm.com]
>> Sent: Thursday, November 02, 2017 3:52 PM
>> To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi at huawei.com>
>> Cc: linux-arm-kernel at lists.infradead.org; linux-pci at vger.kernel.org; linux-
>> acpi at vger.kernel.org; devicetree at vger.kernel.org; iommu at lists.linux-
>> foundation.org; Mark Rutland <Mark.Rutland at arm.com>; xieyisheng (A)
>> <xieyisheng1 at huawei.com>; Gabriele Paoloni
>> <gabriele.paoloni at huawei.com>; Catalin Marinas
>> <Catalin.Marinas at arm.com>; Will Deacon <Will.Deacon at arm.com>;
>> okaya at codeaurora.org; yi.l.liu at intel.com; Lorenzo Pieralisi
>> <Lorenzo.Pieralisi at arm.com>; ashok.raj at intel.com; tn at semihalf.com;
>> joro at 8bytes.org; rfranz at cavium.com; lenb at kernel.org;
>> jacob.jun.pan at linux.intel.com; alex.williamson at redhat.com;
>> robh+dt at kernel.org; Leizhen (ThunderTown) <thunder.leizhen at huawei.com>;
>> bhelgaas at google.com; dwmw2 at infradead.org; liubo (CU)
>> <liubo95 at huawei.com>; rjw at rjwysocki.net; robdclark at gmail.com;
>> hanjun.guo at linaro.org; Sudeep Holla <Sudeep.Holla at arm.com>; Robin
>> Murphy <Robin.Murphy at arm.com>; nwatters at codeaurora.org; Linuxarm
>> <linuxarm at huawei.com>
>> Subject: Re: [RFCv2 PATCH 14/36] iommu/arm-smmu-v3: Add support for
>> Substream IDs
>>
>> Hi Shameer,
>>
>> On Thu, Nov 02, 2017 at 12:49:32PM +0000, Shameerali Kolothum Thodi wrote:
>>> We had a go with this series on HiSIlicon D05 platform which doesn't have
>>> support for ssids/ATS/PRI, to make sure it generally works.
>>>
>>> But observed the below crash on boot,
>>>
>>> [   16.009084] WARNING: CPU: 59 PID: 391 at mm/page_alloc.c:3883
>> __alloc_pages_nodemask+0x19c/0xc48
>>> [   16.026797] Modules linked in:
>>> [   16.032944] CPU: 59 PID: 391 Comm: kworker/59:1 Not tainted 4.14.0-rc1-
>> 159539-ge42aca3 #236
>>> [...]
>>> [   16.068206] Workqueue: events deferred_probe_work_func
>>> [   16.078557] task: ffff8017d38a0000 task.stack: ffff00000b198000
>>> [   16.090486] PC is at __alloc_pages_nodemask+0x19c/0xc48
>>> [   16.101013] LR is at __alloc_pages_nodemask+0xe0/0xc48
>>> [   16.469220] [<ffff000008186b94>] __alloc_pages_nodemask+0x19c/0xc48
>>> [   16.481854] [<ffff0000081d65b0>] alloc_pages_current+0x80/0xcc
>>> [   16.493607] [<ffff000008182be8>] __get_free_pages+0xc/0x38
>>> [   16.504661] [<ffff0000083c4d58>] swiotlb_alloc_coherent+0x64/0x190
>>> [   16.517117] [<ffff00000809824c>] __dma_alloc+0x110/0x204
>>> [   16.527820] [<ffff00000858e850>] dmam_alloc_coherent+0x88/0xf0
>>> [   16.539575] [<ffff000008568884>]
>> arm_smmu_domain_finalise_s1+0x60/0x248
>>> [   16.552909] [<ffff00000856c104>] arm_smmu_attach_dev+0x264/0x300
>>> [   16.565013] [<ffff00000855d40c>] __iommu_attach_device+0x48/0x5c
>>> [   16.577117] [<ffff00000855e698>] iommu_group_add_device+0x144/0x3a4
>>> [   16.589746] [<ffff00000855ed18>] iommu_group_get_for_dev+0x70/0xf8
>>> [   16.602201] [<ffff00000856a314>] arm_smmu_add_device+0x1a4/0x418
>>> [   16.614308] [<ffff00000849dfcc>] iort_iommu_configure+0xf0/0x16c
>>> [   16.626416] [<ffff000008468c50>] acpi_dma_configure+0x30/0x70
>>> [   16.637994] [<ffff00000858f00c>] dma_configure+0xa8/0xd4
>>> [   16.648695] [<ffff00000857706c>] driver_probe_device+0x1a4/0x2dc
>>> [   16.673081] [<ffff0000085752c8>] bus_for_each_drv+0x54/0x94
>>> [   16.684307] [<ffff000008576db0>] __device_attach+0xc4/0x12c
>>> [   16.695533] [<ffff000008577350>] device_initial_probe+0x10/0x18
>>> [   16.707462] [<ffff0000085762b4>] bus_probe_device+0x90/0x98
>>>
>>> After a bit of debug it looks like on platforms where ssid is not supported,
>>> s1_cfg.num_contexts is set to zero and it eventually results in this crash
>>> in,
>>> arm_smmu_domain_finalise_s1() -->arm_smmu_alloc_cd_tables()-->
>>> arm_smmu_alloc_cd_leaf_table() as num_leaf_entries is zero.
>>>
>>> With the below fix, it works on D05 now,
>>>
>>> diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
>>> index 8ad90e2..51f5821 100644
>>> --- a/drivers/iommu/arm-smmu-v3.c
>>> +++ b/drivers/iommu/arm-smmu-v3.c
>>> @@ -2433,7 +2433,10 @@ static int arm_smmu_domain_finalise(struct
>> iommu_domain *domain,
>>>                         domain->min_pasid = 1;
>>>                         domain->max_pasid = master->num_ssids - 1;
>>>                         smmu_domain->s1_cfg.num_contexts = master->num_ssids;
>>> +               } else {
>>> +                       smmu_domain->s1_cfg.num_contexts = 1;
>>>                 }
>>> +
>>>                 smmu_domain->s1_cfg.can_stall = master->ste.can_stall;
>>>                 break;
>>>         case ARM_SMMU_DOMAIN_NESTED:
>>>
>>>
>>> I am not sure this is right place do this. Please take a look.
>>
>> Thanks for testing the series and reporting the bug. I added the
>> following patch to branch svm/current, does it work for you?
> 
> Yes, it does.
> 
> Thanks,
> Shameer
>  
>> diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
>> index 42c8378624ed..edda466adc81 100644
>> --- a/drivers/iommu/arm-smmu-v3.c
>> +++ b/drivers/iommu/arm-smmu-v3.c
>> @@ -3169,9 +3169,7 @@ static int arm_smmu_add_device(struct device *dev)
>>                 }
>>         }
>>
>> -       if (smmu->ssid_bits)
>> -               master->num_ssids = 1 << min(smmu->ssid_bits,
>> -                                            fwspec->num_pasid_bits);
>> +       master->num_ssids = 1 << min(smmu->ssid_bits, fwspec-
>>> num_pasid_bits);

If fwspec->num_pasid_bits = 0, then master have _one_ num_ssids ?

It seems Shameerali's fix is better ?

>>
>>         if (fwspec->can_stall && smmu->features & ARM_SMMU_FEAT_STALLS) {
>>                 master->can_fault = true;
>