Re: [PATCH] drm/xe/mert: Improve handling of MERT CAT errors

["Laguna, Lukasz" <lukasz.laguna@intel.com>]

On 1/12/2026 19:37, Michal Wajdeczko wrote:
> All MERT catastrophic errors but VF's LMTT fault are serious, so
> we shouldn't limit our handling only to print debug messages.
>
> Change CATERR message to error level and then declare the device
> as wedged to match expectation from the design document. For the
> LMTT faults, add a note about adding tracking of this unexpected
> VF activity.
>
> While at it, rename register fields defnitions to match the BSpec.
> Also drop trailing include guard name from the regs.h file.
>
> BSpec: 74625
> Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
> Cc: Lukasz Laguna <lukasz.laguna@intel.com>

Thanks for the patch!
Reviewed-by: Lukasz Laguna <lukasz.laguna@intel.com>

> ---
>   drivers/gpu/drm/xe/regs/xe_mert_regs.h | 10 +++---
>   drivers/gpu/drm/xe/xe_mert.c           | 43 ++++++++++++++++++++------
>   2 files changed, 39 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/gpu/drm/xe/regs/xe_mert_regs.h b/drivers/gpu/drm/xe/regs/xe_mert_regs.h
> index c345e11ceea8..99e5a26da657 100644
> --- a/drivers/gpu/drm/xe/regs/xe_mert_regs.h
> +++ b/drivers/gpu/drm/xe/regs/xe_mert_regs.h
> @@ -11,11 +11,13 @@
>   #define MERT_LMEM_CFG				XE_REG(0x1448b0)
>   
>   #define MERT_TLB_CT_INTR_ERR_ID_PORT		XE_REG(0x145190)
> -#define   MERT_TLB_CT_VFID_MASK			REG_GENMASK(16, 9)
> -#define   MERT_TLB_CT_ERROR_MASK		REG_GENMASK(5, 0)
> -#define     MERT_TLB_CT_LMTT_FAULT		0x05
> +#define   CATERR_VFID				REG_GENMASK(16, 9)
> +#define   CATERR_CODES				REG_GENMASK(5, 0)
> +#define     CATERR_NO_ERROR			0x00
> +#define     CATERR_UNMAPPED_GGTT		0x01
> +#define     CATERR_LMTT_FAULT			0x05
>   
>   #define MERT_TLB_INV_DESC_A			XE_REG(0x14cf7c)
>   #define   MERT_TLB_INV_DESC_A_VALID		REG_BIT(0)
>   
> -#endif /* _XE_MERT_REGS_H_ */
> +#endif
> diff --git a/drivers/gpu/drm/xe/xe_mert.c b/drivers/gpu/drm/xe/xe_mert.c
> index fc027d2d7a5e..f637df95418b 100644
> --- a/drivers/gpu/drm/xe/xe_mert.c
> +++ b/drivers/gpu/drm/xe/xe_mert.c
> @@ -9,6 +9,7 @@
>   #include "xe_device.h"
>   #include "xe_mert.h"
>   #include "xe_mmio.h"
> +#include "xe_sriov_printk.h"
>   #include "xe_tile.h"
>   
>   /**
> @@ -55,6 +56,37 @@ int xe_mert_invalidate_lmtt(struct xe_device *xe)
>   	return 0;
>   }
>   
> +static void mert_handle_cat_error(struct xe_device *xe)
> +{
> +	struct xe_tile *tile = xe_device_get_root_tile(xe);
> +	u32 reg_val, vfid, code;
> +
> +	reg_val = xe_mmio_read32(&tile->mmio, MERT_TLB_CT_INTR_ERR_ID_PORT);
> +	if (!reg_val)
> +		return;
> +	xe_mmio_write32(&tile->mmio, MERT_TLB_CT_INTR_ERR_ID_PORT, 0);
> +
> +	vfid = FIELD_GET(CATERR_VFID, reg_val);
> +	code = FIELD_GET(CATERR_CODES, reg_val);
> +
> +	switch (code) {
> +	case CATERR_NO_ERROR:
> +		break;
> +	case CATERR_UNMAPPED_GGTT:
> +		xe_sriov_err(xe, "MERT: CAT_ERR: Access to an unmapped GGTT!\n");
> +		xe_device_declare_wedged(xe);
> +		break;
> +	case CATERR_LMTT_FAULT:
> +		xe_sriov_dbg(xe, "MERT: CAT_ERR: VF%u LMTT fault!\n", vfid);
> +		/* XXX: track/report malicious VF activity */
> +		break;
> +	default:
> +		xe_sriov_err(xe, "MERT: Unexpected CAT_ERR code=%#x!\n", code);
> +		xe_device_declare_wedged(xe);
> +		break;
> +	}
> +}
> +
>   /**
>    * xe_mert_irq_handler - Handler for MERT interrupts
>    * @xe: the &xe_device
> @@ -68,20 +100,11 @@ void xe_mert_irq_handler(struct xe_device *xe, u32 master_ctl)
>   	struct xe_mert *mert = &tile->mert;
>   	unsigned long flags;
>   	u32 reg_val;
> -	u8 err;
>   
>   	if (!(master_ctl & SOC_H2DMEMINT_IRQ))
>   		return;
>   
> -	reg_val = xe_mmio_read32(&tile->mmio, MERT_TLB_CT_INTR_ERR_ID_PORT);
> -	xe_mmio_write32(&tile->mmio, MERT_TLB_CT_INTR_ERR_ID_PORT, 0);
> -
> -	err = FIELD_GET(MERT_TLB_CT_ERROR_MASK, reg_val);
> -	if (err == MERT_TLB_CT_LMTT_FAULT)
> -		drm_dbg(&xe->drm, "MERT catastrophic error: LMTT fault (VF%u)\n",
> -			FIELD_GET(MERT_TLB_CT_VFID_MASK, reg_val));
> -	else if (err)
> -		drm_dbg(&xe->drm, "MERT catastrophic error: Unexpected fault (0x%x)\n", err);
> +	mert_handle_cat_error(xe);
>   
>   	spin_lock_irqsave(&mert->lock, flags);
>   	if (mert->tlb_inv_triggered) {