[PATCH v7 02/12] drm/xe: Correct BMG VSEC header sizing

[David Box]

On Wed, Jul 09, 2025 at 02:44:48PM -0400, Michael J. Ruhl wrote:
> The intel_vsec_header information for the crashlog feature is
> incorrect.
> 
> Update the VSEC header with correct sizing and count.
> 
> Since the crashlog entries are "merged" (num_entries = 2), the
> separate capabilities entries must be merged as well.
> 
> Acked-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
> Fixes: 0c45e76fcc62 ("drm/xe/vsec: Support BMG devices")
> Signed-off-by: Michael J. Ruhl <michael.j.ruhl at intel.com>
> ---
>  drivers/gpu/drm/xe/xe_vsec.c | 20 +++++---------------
>  1 file changed, 5 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_vsec.c b/drivers/gpu/drm/xe/xe_vsec.c
> index 3e573b0b7ebd..67238fc57a4d 100644
> --- a/drivers/gpu/drm/xe/xe_vsec.c
> +++ b/drivers/gpu/drm/xe/xe_vsec.c
> @@ -32,28 +32,18 @@ static struct intel_vsec_header bmg_telemetry = {
>  	.offset = BMG_DISCOVERY_OFFSET,
>  };
>  
> -static struct intel_vsec_header bmg_punit_crashlog = {
> -	.length = 0x10,
> +static struct intel_vsec_header bmg_crashlog = {
> +	.length = 0x18,

This doesn't look right. The length field is meant to represent the size
of the entire DVSEC, and it should remain 0x10 even for Crashlog.

This field really ought to be validated in vsec.c, but I see that it
isn’t currently. The rev field, which also isn’t set here, determines the
length. When rev is 1, the length is 0x10. vsec does a basic revision
check when reading the capability from config space but doesn’t validate
this driver-provided structure. That’s a gap I’ll take care of
separately.

For now, even though this length value isn’t actually read by vsec.c,
it should still be set correctly to 0x10. Also, add the rev field here
and set it to 1. I see multiple headers missing the rev. That should be
fixed in a separate patch ahead of this one. All Intel DVEC capabilities
use revision 1.

David

>  	.id = VSEC_ID_CRASHLOG,
> -	.num_entries = 1,
> -	.entry_size = 4,
> +	.num_entries = 2,
> +	.entry_size = 6,
>  	.tbir = 0,
>  	.offset = BMG_DISCOVERY_OFFSET + 0x60,
>  };
>  
> -static struct intel_vsec_header bmg_oobmsm_crashlog = {
> -	.length = 0x10,
> -	.id = VSEC_ID_CRASHLOG,
> -	.num_entries = 1,
> -	.entry_size = 4,
> -	.tbir = 0,
> -	.offset = BMG_DISCOVERY_OFFSET + 0x78,
> -};
> -
>  static struct intel_vsec_header *bmg_capabilities[] = {
>  	&bmg_telemetry,
> -	&bmg_punit_crashlog,
> -	&bmg_oobmsm_crashlog,
> +	&bmg_crashlog,
>  	NULL
>  };
>  
> -- 
> 2.50.0
> 
>