Re: [PATCH v4 2/8] iommu/amd: Add debugfs support to dump IOMMU MMIO registers

[Dheeraj Kumar Srivastava <dheerajkumar.srivastava@amd.com>]

Hi Vasant,

On 3/19/2025 10:20 PM, Vasant Hegde wrote:
> Dheeraj,
> 
> 
> On 3/17/2025 5:28 PM, Dheeraj Kumar Srivastava wrote:
>> Analyzing IOMMU MMIO registers gives a view of what IOMMU is
>> configured with on the system and is helpful to debug issues
>> with IOMMU.
>>
>> eg.
>> -> To get mmio registers value at offset 0x18 for iommu<x> (say, iommu00)
>>     # echo "0x18" > /sys/kernel/debug/iommu/amd/iommu00/mmio
>>     # cat /sys/kernel/debug/iommu/amd/iommu00/mmio
>>
>> Signed-off-by: Dheeraj Kumar Srivastava <dheerajkumar.srivastava@amd.com>
>> ---
>>   drivers/iommu/amd/debugfs.c | 47 +++++++++++++++++++++++++++++++++++++
>>   1 file changed, 47 insertions(+)
>>
>> diff --git a/drivers/iommu/amd/debugfs.c b/drivers/iommu/amd/debugfs.c
>> index ff9520e002be..c61d52420c5f 100644
>> --- a/drivers/iommu/amd/debugfs.c
>> +++ b/drivers/iommu/amd/debugfs.c
>> @@ -15,6 +15,50 @@
>>   static struct dentry *amd_iommu_debugfs;
>>   
>>   #define	MAX_NAME_LEN	20
>> +#define	OFS_IN_SZ	8
>> +
>> +static int mmio_offset = -1;
> 
> 
> Somehow I missed to catch this earlier. Here you have global variable but mmio
> is defined per IOMMU. Shouldn't we track it per IOMMU ?

Yes correct we need to maintain per iommu global variables for mmio and 
capability registers offset. I have sent v5 addressing this. Please find 
some time to review it.

Thanks
Dheeraj

> 
> -Vasant
>