[RFCv2 PATCH 14/36] iommu/arm-smmu-v3: Add support for Substream IDs
Jean-Philippe Brucker
jean-philippe.brucker at arm.com
Fri Nov 3 02:37:02 PDT 2017
On 03/11/17 05:45, Yisheng Xie wrote:
> 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 ?
Yes, the context table allocator always needs to allocate at least one
entry, even if the master or SMMU doesn't support SSID. I think an earlier
version called this field "num_contexts", maybe we should got back to that
name for clarity?
Thanks,
Jean
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