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

[Dheeraj Kumar Srivastava]

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@xxxxxxx>
> > ---
> >   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