[PATCH v2] drm/xe/vsec: Allow for kernel context access

[Lucas De Marchi]

On Thu, May 08, 2025 at 01:09:06PM +0000, Ruhl, Michael J wrote:
>>-----Original Message-----
>>From: De Marchi, Lucas <lucas.demarchi at intel.com>
>>Sent: Wednesday, May 7, 2025 3:46 PM
>>To: Ruhl, Michael J <michael.j.ruhl at intel.com>
>>Cc: intel-xe at lists.freedesktop.org; Johnstone, Nicholas
>><nicholas.johnstone at intel.com>; Box, David E <david.e.box at intel.com>; Vivi,
>>Rodrigo <rodrigo.vivi at intel.com>
>>Subject: Re: [PATCH v2] drm/xe/vsec: Allow for kernel context access
>>
>>On Wed, May 07, 2025 at 03:37:40PM -0400, Michael J. Ruhl wrote:
>>>The PMT driver API allows kernel level access to device
>>
>>ahn? What's that supposed to mean? what's the context that is calling
>>this ?
>
>Hi Lucas,
>
>The PMT exports the pmt_telem_read_mmio() function which accesses HW registers
>for telemetry information.
>
>In this use case the SOCwatch kernel driver is accessing the API trying to read telemetry
>information.
>
>Since is happening from kernel level rather than user level, the mutex throws the
>"might sleep" context error.
>
>I tried to distill this the above comment...  Does adding the content above explain this
>enough, or should I be more expansive (what details do you need?)?

being called from another kernel module doesn't explain anything
regarding being allowed to sleep or not. Also depending on the context a
spinlock may not even be sufficient as it may sleep. Without knowing the
caller we can't even know if it should be a spinlock or a raw_spinlock.

Lucas De Marchi