Message-ID: <bfaaad63-a5d7-4ceb-8e1c-d541f76f4037@amd.com>
Date: Wed, 6 Mar 2024 16:37:48 +0100
From: Christian König <christian.koenig@....com>
To: "Khatri, Sunil" <sukhatri@....com>,
 Christian König <ckoenig.leichtzumerken@...il.com>,
 Alex Deucher <alexdeucher@...il.com>
Cc: Sunil Khatri <sunil.khatri@....com>,
 Alex Deucher <alexander.deucher@....com>,
 Shashank Sharma <shashank.sharma@....com>, amd-gfx@...ts.freedesktop.org,
 Pan@...-sunil-navi33.amd.com, Xinhui <Xinhui.Pan@....com>,
 dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
 Mukul Joshi <mukul.joshi@....com>,
 Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam@....com>
Subject: Re: [PATCH] drm/amdgpu: cache in more vm fault information

Am 06.03.24 um 16:13 schrieb Khatri, Sunil:
>
> On 3/6/2024 8:34 PM, Christian König wrote:
>> Am 06.03.24 um 15:29 schrieb Alex Deucher:
>>> On Wed, Mar 6, 2024 at 8:04 AM Khatri, Sunil <sukhatri@....com> wrote:
>>>>
>>>> On 3/6/2024 6:12 PM, Christian König wrote:
>>>>> Am 06.03.24 um 11:40 schrieb Khatri, Sunil:
>>>>>> On 3/6/2024 3:37 PM, Christian König wrote:
>>>>>>> Am 06.03.24 um 10:04 schrieb Sunil Khatri:
>>>>>>>> When an  page fault interrupt is raised there
>>>>>>>> is a lot more information that is useful for
>>>>>>>> developers to analyse the pagefault.
>>>>>>> Well actually those information are not that interesting because
>>>>>>> they are hw generation specific.
>>>>>>>
>>>>>>> You should probably rather use the decoded strings here, e.g. hub,
>>>>>>> client, xcc_id, node_id etc...
>>>>>>>
>>>>>>> See gmc_v9_0_process_interrupt() an example.
>>>>>>> I saw this v9 does provide more information than what v10 and v11
>>>>>>> provide like node_id and fault from which die but thats again very
>>>>>>> specific to IP_VERSION(9, 4, 3)) i dont know why thats information
>>>>>>> is not there in v10 and v11.
>>>>>> I agree to your point but, as of now during a pagefault we are
>>>>>> dumping this information which is useful like which client
>>>>>> has generated an interrupt and for which src and other information
>>>>>> like address. So i think to provide the similar information in the
>>>>>> devcoredump.
>>>>>>
>>>>>> Currently we do not have all this information from either job or vm
>>>>>> being derived from the job during a reset. We surely could add more
>>>>>> relevant information later on as per request but this information is
>>>>>> useful as
>>>>>> eventually its developers only who would use the dump file provided
>>>>>> by customer to debug.
>>>>>>
>>>>>> Below is the information that i dump in devcore and i feel that is
>>>>>> good information but new information could be added which could be
>>>>>> picked later.
>>>>>>
>>>>>>> Page fault information
>>>>>>> [gfxhub] page fault (src_id:0 ring:24 vmid:3 pasid:32773)
>>>>>>> in page starting at address 0x0000000000000000 from client 0x1b 
>>>>>>> (UTCL2)
>>>>> This is a perfect example what I mean. You record in the patch is the
>>>>> client_id, but this is is basically meaningless unless you have 
>>>>> access
>>>>> to the AMD internal hw documentation.
>>>>>
>>>>> What you really need is the client in decoded form, in this case
>>>>> UTCL2. You can keep the client_id additionally, but the decoded 
>>>>> client
>>>>> string is mandatory to have I think.
>>>>>
>>>>> Sure i am capturing that information as i am trying to minimise the
>>>>> memory interaction to minimum as we are still in interrupt context
>>>>> here that why i recorded the integer information compared to decoding
>>>> and writing strings there itself but to postpone till we dump.
>>>>
>>>> Like decoding to the gfxhub/mmhub based on vmhub/vmid_src and client
>>>> string from client id. So are we good to go with the information with
>>>> the above information of sharing details in devcoredump using the
>>>> additional information from pagefault cached.
>>> I think amdgpu_vm_fault_info() has everything you need already (vmhub,
>>> status, and addr).  client_id and src_id are just tokens in the
>>> interrupt cookie so we know which IP to route the interrupt to. We
>>> know what they will be because otherwise we'd be in the interrupt
>>> handler for a different IP.  I don't think ring_id has any useful
>>> information in this context and vmid and pasid are probably not too
>>> useful because they are just tokens to associate the fault with a
>>> process.  It would be better to have the process name.
>
> Just to share context here Alex, i am preparing this for devcoredump, 
> my intention was to replicate the information which in KMD we are 
> sharing in Dmesg for page faults. If assuming we do not add client id 
> specially we would not be able to share enough information in 
> devcoredump.
> It would be just address and hub(gfxhub/mmhub) and i think that is 
> partial information as src id and client id and ip block shares good 
> information.
>
> For process related information we are capturing that information part 
> of dump from existing functionality.
> **** AMDGPU Device Coredump ****
> version: 1
> kernel: 6.7.0-amd-staging-drm-next
> module: amdgpu
> time: 45.084775181
> process_name: soft_recovery_p PID: 1780
>
> Ring timed out details
> IP Type: 0 Ring Name: gfx_0.0.0
>
> Page fault information
> [gfxhub] page fault (src_id:0 ring:24 vmid:3 pasid:32773)
> in page starting at address 0x0000000000000000 from client 0x1b (UTCL2)
> VRAM is lost due to GPU reset!
>
> Regards
> Sunil
>
>>
>> The decoded client name would be really useful I think since the 
>> fault handled is a catch all and handles a whole bunch of different 
>> clients.
>>
>> But that should be ideally passed in as const string instead of the 
>> hw generation specific client_id.
>>
>> As long as it's only a pointer we also don't run into the trouble 
>> that we need to allocate memory for it.
>
> I agree but i prefer adding the client id and decoding it in 
> devcorecump using soc15_ih_clientid_name[fault_info->client_id]) is 
> better else we have to do an sprintf this string to fault_info in irq 
> context which is writing more bytes to memory i guess compared to an 
> integer:)

Well I totally agree that we shouldn't fiddle to much in the interrupt 
handler, but exactly what you suggest here won't work.

The client_id is hw generation specific, so the only one who has that is 
the hw generation specific fault handler. Just compare the defines here:

https://elixir.bootlin.com/linux/latest/source/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c#L83

and here:

https://elixir.bootlin.com/linux/latest/source/drivers/gpu/drm/amd/amdgpu/gfxhub_v11_5_0.c#L38

Regards,
Christian.

>
> We can argue on values like pasid and vmid and ring id to be taken off 
> if they are totally not useful.
>
> Regards
> Sunil
>
>>
>> Christian.
>>
>>>
>>> Alex
>>>
>>>> regards
>>>> sunil
>>>>
>>>>> Regards,
>>>>> Christian.
>>>>>
>>>>>> Regards
>>>>>> Sunil Khatri
>>>>>>
>>>>>>> Regards,
>>>>>>> Christian.
>>>>>>>
>>>>>>>> Add all such information in the last cached
>>>>>>>> pagefault from an interrupt handler.
>>>>>>>>
>>>>>>>> Signed-off-by: Sunil Khatri <sunil.khatri@....com>
>>>>>>>> ---
>>>>>>>>    drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 9 +++++++--
>>>>>>>>    drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h | 7 ++++++-
>>>>>>>>    drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c | 2 +-
>>>>>>>>    drivers/gpu/drm/amd/amdgpu/gmc_v11_0.c | 2 +-
>>>>>>>>    drivers/gpu/drm/amd/amdgpu/gmc_v7_0.c  | 2 +-
>>>>>>>>    drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c  | 2 +-
>>>>>>>>    drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c  | 2 +-
>>>>>>>>    7 files changed, 18 insertions(+), 8 deletions(-)
>>>>>>>>
>>>>>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>>>>>>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>>>>>>>> index 4299ce386322..b77e8e28769d 100644
>>>>>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>>>>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>>>>>>>> @@ -2905,7 +2905,7 @@ void amdgpu_debugfs_vm_bo_info(struct
>>>>>>>> amdgpu_vm *vm, struct seq_file *m)
>>>>>>>>     * Cache the fault info for later use by userspace in 
>>>>>>>> debugging.
>>>>>>>>     */
>>>>>>>>    void amdgpu_vm_update_fault_cache(struct amdgpu_device *adev,
>>>>>>>> -                  unsigned int pasid,
>>>>>>>> +                  struct amdgpu_iv_entry *entry,
>>>>>>>>                      uint64_t addr,
>>>>>>>>                      uint32_t status,
>>>>>>>>                      unsigned int vmhub)
>>>>>>>> @@ -2915,7 +2915,7 @@ void amdgpu_vm_update_fault_cache(struct
>>>>>>>> amdgpu_device *adev,
>>>>>>>> xa_lock_irqsave(&adev->vm_manager.pasids, flags);
>>>>>>>>    -    vm = xa_load(&adev->vm_manager.pasids, pasid);
>>>>>>>> +    vm = xa_load(&adev->vm_manager.pasids, entry->pasid);
>>>>>>>>        /* Don't update the fault cache if status is 0.  In the 
>>>>>>>> multiple
>>>>>>>>         * fault case, subsequent faults will return a 0 status 
>>>>>>>> which is
>>>>>>>>         * useless for userspace and replaces the useful fault
>>>>>>>> status, so
>>>>>>>> @@ -2924,6 +2924,11 @@ void amdgpu_vm_update_fault_cache(struct
>>>>>>>> amdgpu_device *adev,
>>>>>>>>        if (vm && status) {
>>>>>>>>            vm->fault_info.addr = addr;
>>>>>>>>            vm->fault_info.status = status;
>>>>>>>> +        vm->fault_info.client_id = entry->client_id;
>>>>>>>> +        vm->fault_info.src_id = entry->src_id;
>>>>>>>> +        vm->fault_info.vmid = entry->vmid;
>>>>>>>> +        vm->fault_info.pasid = entry->pasid;
>>>>>>>> +        vm->fault_info.ring_id = entry->ring_id;
>>>>>>>>            if (AMDGPU_IS_GFXHUB(vmhub)) {
>>>>>>>>                vm->fault_info.vmhub = AMDGPU_VMHUB_TYPE_GFX;
>>>>>>>>                vm->fault_info.vmhub |=
>>>>>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
>>>>>>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
>>>>>>>> index 047ec1930d12..c7782a89bdb5 100644
>>>>>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
>>>>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
>>>>>>>> @@ -286,6 +286,11 @@ struct amdgpu_vm_fault_info {
>>>>>>>>        uint32_t    status;
>>>>>>>>        /* which vmhub? gfxhub, mmhub, etc. */
>>>>>>>>        unsigned int    vmhub;
>>>>>>>> +    unsigned int    client_id;
>>>>>>>> +    unsigned int    src_id;
>>>>>>>> +    unsigned int    ring_id;
>>>>>>>> +    unsigned int    pasid;
>>>>>>>> +    unsigned int    vmid;
>>>>>>>>    };
>>>>>>>>      struct amdgpu_vm {
>>>>>>>> @@ -605,7 +610,7 @@ static inline void
>>>>>>>> amdgpu_vm_eviction_unlock(struct amdgpu_vm *vm)
>>>>>>>>    }
>>>>>>>>      void amdgpu_vm_update_fault_cache(struct amdgpu_device *adev,
>>>>>>>> -                  unsigned int pasid,
>>>>>>>> +                  struct amdgpu_iv_entry *entry,
>>>>>>>>                      uint64_t addr,
>>>>>>>>                      uint32_t status,
>>>>>>>>                      unsigned int vmhub);
>>>>>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c
>>>>>>>> b/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c
>>>>>>>> index d933e19e0cf5..6b177ce8db0e 100644
>>>>>>>> --- a/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c
>>>>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c
>>>>>>>> @@ -150,7 +150,7 @@ static int gmc_v10_0_process_interrupt(struct
>>>>>>>> amdgpu_device *adev,
>>>>>>>>            status = RREG32(hub->vm_l2_pro_fault_status);
>>>>>>>>            WREG32_P(hub->vm_l2_pro_fault_cntl, 1, ~1);
>>>>>>>>    -        amdgpu_vm_update_fault_cache(adev, entry->pasid, addr,
>>>>>>>> status,
>>>>>>>> +        amdgpu_vm_update_fault_cache(adev, entry, addr, status,
>>>>>>>>                             entry->vmid_src ? AMDGPU_MMHUB0(0) :
>>>>>>>> AMDGPU_GFXHUB(0));
>>>>>>>>        }
>>>>>>>>    diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v11_0.c
>>>>>>>> b/drivers/gpu/drm/amd/amdgpu/gmc_v11_0.c
>>>>>>>> index 527dc917e049..bcf254856a3e 100644
>>>>>>>> --- a/drivers/gpu/drm/amd/amdgpu/gmc_v11_0.c
>>>>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/gmc_v11_0.c
>>>>>>>> @@ -121,7 +121,7 @@ static int gmc_v11_0_process_interrupt(struct
>>>>>>>> amdgpu_device *adev,
>>>>>>>>            status = RREG32(hub->vm_l2_pro_fault_status);
>>>>>>>>            WREG32_P(hub->vm_l2_pro_fault_cntl, 1, ~1);
>>>>>>>>    -        amdgpu_vm_update_fault_cache(adev, entry->pasid, addr,
>>>>>>>> status,
>>>>>>>> +        amdgpu_vm_update_fault_cache(adev, entry, addr, status,
>>>>>>>>                             entry->vmid_src ? AMDGPU_MMHUB0(0) :
>>>>>>>> AMDGPU_GFXHUB(0));
>>>>>>>>        }
>>>>>>>>    diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v7_0.c
>>>>>>>> b/drivers/gpu/drm/amd/amdgpu/gmc_v7_0.c
>>>>>>>> index 3da7b6a2b00d..e9517ebbe1fd 100644
>>>>>>>> --- a/drivers/gpu/drm/amd/amdgpu/gmc_v7_0.c
>>>>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/gmc_v7_0.c
>>>>>>>> @@ -1270,7 +1270,7 @@ static int gmc_v7_0_process_interrupt(struct
>>>>>>>> amdgpu_device *adev,
>>>>>>>>        if (!addr && !status)
>>>>>>>>            return 0;
>>>>>>>>    -    amdgpu_vm_update_fault_cache(adev, entry->pasid,
>>>>>>>> +    amdgpu_vm_update_fault_cache(adev, entry,
>>>>>>>>                         ((u64)addr) << AMDGPU_GPU_PAGE_SHIFT,
>>>>>>>> status, AMDGPU_GFXHUB(0));
>>>>>>>>          if (amdgpu_vm_fault_stop == AMDGPU_VM_FAULT_STOP_FIRST)
>>>>>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c
>>>>>>>> b/drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c
>>>>>>>> index d20e5f20ee31..a271bf832312 100644
>>>>>>>> --- a/drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c
>>>>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c
>>>>>>>> @@ -1438,7 +1438,7 @@ static int gmc_v8_0_process_interrupt(struct
>>>>>>>> amdgpu_device *adev,
>>>>>>>>        if (!addr && !status)
>>>>>>>>            return 0;
>>>>>>>>    -    amdgpu_vm_update_fault_cache(adev, entry->pasid,
>>>>>>>> +    amdgpu_vm_update_fault_cache(adev, entry,
>>>>>>>>                         ((u64)addr) << AMDGPU_GPU_PAGE_SHIFT,
>>>>>>>> status, AMDGPU_GFXHUB(0));
>>>>>>>>          if (amdgpu_vm_fault_stop == AMDGPU_VM_FAULT_STOP_FIRST)
>>>>>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
>>>>>>>> b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
>>>>>>>> index 47b63a4ce68b..dc9fb1fb9540 100644
>>>>>>>> --- a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
>>>>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
>>>>>>>> @@ -666,7 +666,7 @@ static int gmc_v9_0_process_interrupt(struct
>>>>>>>> amdgpu_device *adev,
>>>>>>>>        rw = REG_GET_FIELD(status, 
>>>>>>>> VM_L2_PROTECTION_FAULT_STATUS, RW);
>>>>>>>>        WREG32_P(hub->vm_l2_pro_fault_cntl, 1, ~1);
>>>>>>>>    -    amdgpu_vm_update_fault_cache(adev, entry->pasid, addr,
>>>>>>>> status, vmhub);
>>>>>>>> +    amdgpu_vm_update_fault_cache(adev, entry, addr, status, 
>>>>>>>> vmhub);
>>>>>>>>          dev_err(adev->dev,
>>>>>>>>            "VM_L2_PROTECTION_FAULT_STATUS:0x%08X\n",
>>

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