Re: [PATCH 04/12] drm/amdgpu: add amdgpu_xcp_get_xcc_mask helper

["Lazar, Lijo" <lijo.lazar@amd.com>]

On 22-Sep-26 7:41 PM, James Zhu wrote:
> 
> On 2026-09-22 09:45, Lazar, Lijo wrote:
>>
>>
>> On 22-Sep-26 7:05 PM, James Zhu wrote:
>>>
>>> On 2026-09-22 01:22, Lazar, Lijo wrote:
>>>>
>>>>
>>>> On 22-Sep-26 1:33 AM, James Zhu wrote:
>>>>> Add amdgpu_xcp_get_xcc_mask() to return the XCC instance mask for a 
>>>>> given
>>>>> XCP partition. This is needed by upcoming SPM (Stream Performance 
>>>>> Monitor)
>>>>> support, which programs hardware per partition and must operate 
>>>>> only on
>>>>> the XCCs that belong to a given XCP.
>>>>>
>>>>> For partitioned systems the helper returns only the XCCs belonging 
>>>>> to the
>>>>> specified XCP. When @xcp_id is AMDGPU_XCP_NO_PARTITION (or the 
>>>>> device is
>>>>> not partitioned) it returns the device's full XCC mask (e.g. 0xFF 
>>>>> for an
>>>>> 8-XCC device). Note that the full device mask is returned even on a
>>>>> partitioned device; callers that require partition isolation (e.g. 
>>>>> SPM)
>>>>> must reject AMDGPU_XCP_NO_PARTITION on a partitioned device 
>>>>> themselves.
>>>>>
>>>>
>>>> Could you clarifiy on this part - xcp_id = AMDGPU_XCP_NO_PARTITION 
>>>> usage on 8-XCC device?
>>>>
>>>> The default state on a multi-XCC device after driver load is all 
>>>> XCCs in a single partition called SPX. It should have at least one 
>>>> partition valid.
>>>
>>> [JZ] Yes, 8-XCC device should not reach AMDGPU_XCP_NO_PARTITION case.
>>>
>>> the if(!xcp_mgr ||xcp_id ==AMDGPU_XCP_NO_PARTITION) mainly covers non 
>>> partition device, I can remove the above comments which don't reflect 
>>> the source accurately.
>>
>> Then I'm not sure what issue this is fixing.
>>
>> Multi-xcc devices will be in SPX mode and will return a mask with all 
>> the XCCs. Non-multi xcc devices are expected to have this set to 1 
>> anyway to reflect that a single GC is present always.
> [JZ] Just realized a Fixes tag is added. I think somehow AI review added 
> it, and I did not check properly, is should be removed also. Sorry for 
> this confusing!

I see that it also added an external function like this -

amdgpu_xcp_get_xcc_mask

The expectation is any IP instance mask within a partition needs to 
obtained through - amdgpu_xcp_get_inst_details

Also, amdgpu_xcp_get_xcc_mask provides this which is not correct -

*xcc_mask = adev->gfx.xcc_mask

xcp instance mask operates only return logical mask of instances present 
(xcc_mask could include disabled ones also).

Thanks,
Lijo

>>
>> Thanks,
>> Lijo
>>
>>>> Thanks,
>>>> Lioj
>>>>
>>>>> amdgpu_xcp_get_num_xcc() is reworked to take (adev, xcp_id) and 
>>>>> derive the
>>>>> count from this helper via hweight32(). The helper is defined out 
>>>>> of line
>>>>> in amdgpu_xcp.c so that the static inline in amdgpu_xcp.h never has to
>>>>> dereference the (incomplete) struct amdgpu_device; it only passes the
>>>>> pointer through.
>>>>>
>>>>> This is a user-visible change: amdgpu_xcp_get_num_xcc() previously
>>>>> returned 1 for non-partitioned systems (and for 
>>>>> AMDGPU_XCP_NO_PARTITION),
>>>>> and now returns the actual XCC count (e.g. 8 for an 8-XCC device). 
>>>>> CWSR
>>>>> callers (amdgpu_kms.c, amdgpu_userq.c, mes_userqueue.c) scale the 
>>>>> per-XCC
>>>>> control-stack and debug-memory sizes by num_xcc, so the uAPI-visible
>>>>> ctl_stack_size and dbg_mem_size values grow accordingly to match the
>>>>> actual hardware resource requirements, which were previously 
>>>>> undersized.
>>>>>
>>>>> Fixes: 4cd417bfec49 ("drm/amdgpu: Add helper function to get xcc 
>>>>> count")
>>>>> Signed-off-by: James Zhu <James.Zhu@amd.com>
>>>>> Reviewed-by: Bing Ma <bing.ma@amd.com>
>>>>> ---
>>>>>   drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c    |  2 +-
>>>>>   drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c  |  2 +-
>>>>>   drivers/gpu/drm/amd/amdgpu/amdgpu_xcp.c    | 48 +++++++++++++++++ 
>>>>> +++++
>>>>>   drivers/gpu/drm/amd/amdgpu/amdgpu_xcp.h    | 32 +++++++--------
>>>>>   drivers/gpu/drm/amd/amdgpu/mes_userqueue.c |  3 +-
>>>>>   5 files changed, 66 insertions(+), 21 deletions(-)
>>>>>
>>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c b/drivers/gpu/ 
>>>>> drm/amd/amdgpu/amdgpu_kms.c
>>>>> index 57fa69c0382d..7782ccd4d28f 100644
>>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
>>>>> @@ -1501,7 +1501,7 @@ int amdgpu_info_ioctl(struct drm_device *dev, 
>>>>> void *data, struct drm_file *filp)
>>>>>           fpriv = (struct amdgpu_fpriv *)filp->driver_priv;
>>>>>           if (!amdgpu_trap_is_enabled(adev) || !fpriv->trap_obj)
>>>>>               return -EOPNOTSUPP;
>>>>> -        num_xcc = amdgpu_xcp_get_num_xcc(adev->xcp_mgr, fpriv- 
>>>>> >xcp_id);
>>>>> +        num_xcc = amdgpu_xcp_get_num_xcc(adev, fpriv->xcp_id);
>>>>>           cwsr_info.ctl_stack_size =
>>>>>               adev->trap_info->cwsr.xcc_ctl_stack_sz * num_xcc;
>>>>>           cwsr_info.dbg_mem_size =
>>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c b/drivers/ 
>>>>> gpu/ drm/amd/amdgpu/amdgpu_userq.c
>>>>> index db09e879b85e..d19af9cb6ee1 100644
>>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
>>>>> @@ -258,7 +258,7 @@ int 
>>>>> amdgpu_userq_input_trap_params_validate(struct 
>>>>> amdgpu_usermode_queue *queue,
>>>>>       int num_xcc;
>>>>>       int r;
>>>>>   -    num_xcc = amdgpu_xcp_get_num_xcc(adev->xcp_mgr, fpriv->xcp_id);
>>>>> +    num_xcc = amdgpu_xcp_get_num_xcc(adev, fpriv->xcp_id);
>>>>>       r = amdgpu_trap_validate_params(queue->userq_mgr->adev, 
>>>>> trap_params,
>>>>>                       num_xcc);
>>>>>       if (r)
>>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_xcp.c b/drivers/gpu/ 
>>>>> drm/amd/amdgpu/amdgpu_xcp.c
>>>>> index 2a56f5ec9c76..90846d55292b 100644
>>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_xcp.c
>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_xcp.c
>>>>> @@ -390,6 +390,54 @@ int amdgpu_xcp_get_inst_details(struct 
>>>>> amdgpu_xcp *xcp,
>>>>>       return 0;
>>>>>   }
>>>>>   +/**
>>>>> + * amdgpu_xcp_get_xcc_mask - Get XCC instance mask for a partition
>>>>> + * @adev: amdgpu device pointer
>>>>> + * @xcp_id: XCP partition ID
>>>>> + * @xcc_mask: output parameter for XCC instance mask
>>>>> + *
>>>>> + * Returns the XCC instance mask for the specified XCP partition.
>>>>> + * For partitioned systems, returns only the XCCs belonging to 
>>>>> this XCP.
>>>>> + *
>>>>> + * When @xcp_id is AMDGPU_XCP_NO_PARTITION (or the device is not
>>>>> + * partitioned), the device's full XCC mask is returned (e.g. 0xFF 
>>>>> for an
>>>>> + * 8-XCC device). Note that the full device mask is returned even 
>>>>> on a
>>>>> + * partitioned device: callers that require partition isolation 
>>>>> (e.g. SPM)
>>>>> + * must reject AMDGPU_XCP_NO_PARTITION on a partitioned device 
>>>>> themselves.
>>>>> + *
>>>>> + * Note: On error, xcc_mask is undefined. Callers must check 
>>>>> return code
>>>>> + * and only read xcc_mask when return == 0.
>>>>> + *
>>>>> + * Return: 0 on success (non-partitioned systems or valid XCP found),
>>>>> + *         -EINVAL if xcc_mask is NULL, no matching XCP id is 
>>>>> found, or the
>>>>> + *         partition's GFX IP details are unavailable
>>>>> + */
>>>>> +int amdgpu_xcp_get_xcc_mask(struct amdgpu_device *adev, int xcp_id,
>>>>> +                uint32_t *xcc_mask)
>>>>> +{
>>>>> +    struct amdgpu_xcp_mgr *xcp_mgr = adev->xcp_mgr;
>>>>> +    struct amdgpu_xcp *xcp;
>>>>> +    int i;
>>>>> +
>>>>> +    if (!xcc_mask)
>>>>> +        return -EINVAL;
>>>>> +
>>>>> +    if (!xcp_mgr || xcp_id == AMDGPU_XCP_NO_PARTITION) {
>>>>> +        /* Non-partitioned: return the device's full XCC mask. */
>>>>> +        *xcc_mask = adev->gfx.xcc_mask;
>>>>> +        return 0;
>>>>> +    }
>>>>> +
>>>>> +    /* Partitioned system: get this XCP's XCCs */
>>>>> +    for_each_xcp(xcp_mgr, xcp, i) {
>>>>> +        if (xcp->id == xcp_id)
>>>>> +            return amdgpu_xcp_get_inst_details(xcp, AMDGPU_XCP_GFX,
>>>>> +                               xcc_mask);
>>>>> +    }
>>>>> +
>>>>> +    return -EINVAL;
>>>>> +}
>>>>> +
>>>>>   int amdgpu_xcp_dev_register(struct amdgpu_device *adev,
>>>>>               const struct pci_device_id *ent)
>>>>>   {
>>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_xcp.h b/drivers/gpu/ 
>>>>> drm/amd/amdgpu/amdgpu_xcp.h
>>>>> index 692508be23fb..6eed82ad49b1 100644
>>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_xcp.h
>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_xcp.h
>>>>> @@ -44,6 +44,7 @@
>>>>>   #define XCP_INST_MASK(num_inst, xcp_id)        \
>>>>>       (num_inst ? GENMASK(num_inst - 1, 0) << (xcp_id * num_inst) : 0)
>>>>>   +struct amdgpu_device;
>>>>>   struct amdgpu_fpriv;
>>>>>     enum AMDGPU_XCP_IP_BLOCK {
>>>>> @@ -219,26 +220,23 @@ amdgpu_get_next_xcp(struct amdgpu_xcp_mgr 
>>>>> *xcp_mgr, int *from)
>>>>>       for (i = 0, xcp = amdgpu_get_next_xcp(xcp_mgr, &i); xcp; \
>>>>>            ++i, xcp = amdgpu_get_next_xcp(xcp_mgr, &i))
>>>>>   -static inline int amdgpu_xcp_get_num_xcc(struct amdgpu_xcp_mgr 
>>>>> *xcp_mgr,
>>>>> -                     int xcp_id)
>>>>> +int amdgpu_xcp_get_xcc_mask(struct amdgpu_device *adev, int xcp_id,
>>>>> +                uint32_t *xcc_mask);
>>>>> +
>>>>> +static inline int amdgpu_xcp_get_num_xcc(struct amdgpu_device 
>>>>> *adev, int xcp_id)
>>>>>   {
>>>>> -    struct amdgpu_xcp *xcp;
>>>>>       uint32_t xcc_mask;
>>>>> -    int i, r;
>>>>> -
>>>>> -    if (!xcp_mgr || xcp_id == AMDGPU_XCP_NO_PARTITION)
>>>>> +    int r, count;
>>>>> +
>>>>> +    /* Derive the XCC count from the partition's XCC mask (or the 
>>>>> full
>>>>> +     * device mask when not partitioned). amdgpu_xcp_get_xcc_mask()
>>>>> +     * handles both partitioned and non-partitioned cases.
>>>>> +     */
>>>>> +    r = amdgpu_xcp_get_xcc_mask(adev, xcp_id, &xcc_mask);
>>>>> +    if (unlikely(r))
>>>>>           return 1;
>>>>> -    for_each_xcp(xcp_mgr, xcp, i) {
>>>>> -        if (xcp->id == xcp_id) {
>>>>> -            r = amdgpu_xcp_get_inst_details(xcp, AMDGPU_XCP_GFX,
>>>>> -                            &xcc_mask);
>>>>> -            if (unlikely(r))
>>>>> -                return 1;
>>>>> -            else
>>>>> -                return hweight32(xcc_mask);
>>>>> -        }
>>>>> -    }
>>>>>   -    return 1;
>>>>> +    count = hweight32(xcc_mask);
>>>>> +    return count ? count : 1;
>>>>>   }
>>>>>   #endif
>>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/mes_userqueue.c b/drivers/ 
>>>>> gpu/drm/amd/amdgpu/mes_userqueue.c
>>>>> index 16aa22b25098..1c7b2f3227e5 100644
>>>>> --- a/drivers/gpu/drm/amd/amdgpu/mes_userqueue.c
>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/mes_userqueue.c
>>>>> @@ -503,8 +503,7 @@ static int mes_userq_mqd_create(struct 
>>>>> amdgpu_usermode_queue *queue,
>>>>>                   uq_mgr_to_fpriv(queue->userq_mgr);
>>>>>               int num_xcc;
>>>>>   -            num_xcc = amdgpu_xcp_get_num_xcc(adev->xcp_mgr,
>>>>> -                             fpriv->xcp_id);
>>>>> +            num_xcc = amdgpu_xcp_get_num_xcc(adev, fpriv->xcp_id);
>>>>>               trap_params.ctx_save_area_address =
>>>>>                   compute_mqd->ctx_save_area_va;
>>>>>               trap_params.cwsr_sz = compute_mqd->ctx_save_area_size;
>>>>
>>