Message-ID: <81f2c1bf-6c44-4d7c-aab5-83fa097a21ff@amd.com>
Date: Wed, 6 Mar 2024 21:51:11 +0530
From: "Khatri, Sunil" <sukhatri@....com>
To: Alex Deucher <alexdeucher@...il.com>
Cc: Christian König <christian.koenig@....com>,
 Christian König <ckoenig.leichtzumerken@...il.com>,
 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


On 3/6/2024 9:45 PM, Alex Deucher wrote:
> On Wed, Mar 6, 2024 at 11:06 AM Khatri, Sunil <sukhatri@....com> wrote:
>>
>> On 3/6/2024 9:07 PM, Christian König wrote:
>>> 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
>>>
>>>
>> Got your point. Let me see but this is a lot of work in irq context.
>> Either we can drop totally the client id thing as alex is suggesting
>> here as its always be same client and src id or let me come up with a
>> patch and see if its acceptable.
>>
>> Also as Alex pointed we need to decode from status register which kind
>> of page fault it is (permission, read, write etc) this all is again
>> family specific and thats all in IRQ context. Not feeling good about it
>> but let me try to share all that in a new patch.
>>
> I don't think you need to decode it.  As long as you have a way to
> identify the chip, we can just include the raw status register and the
> developer can decode it when they look at the devcoredump.

Got it Alex.
I will try to add chip information along with status register value 
only. We have below two values in adev, i think this along with status 
register should suffice.
enum amd_asic_type        asic_type;
uint32_t            family;

Regards
Sunil Khatri

>
> Alex
>
>
>> Regards
>> Sunil.
>>
>>> 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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