Re: [Intel-gfx] [PATCH 4/6] drm/i915/gsc: Do a driver-FLR on unload if GSC was loaded

["Ceraolo Spurio, Daniele" <daniele.ceraolospurio@intel.com>]

On 11/21/2022 3:16 PM, Daniele Ceraolo Spurio wrote:
> If the GSC was loaded, the only way to stop it during the driver unload
> flow is to do a driver-FLR.
> The driver-FLR is not the same as PCI config space FLR in that
> it doesn't reset the SGUnit and doesn't modify the PCI config
> space. Thus, it doesn't require a re-enumeration of the PCI BARs.
> However, the driver-FLR does cause a memory wipe of graphics memory
> on all discrete GPU platforms or a wipe limited to stolen memory
> on the integrated GPU platforms.
>
> We perform the FLR as the last action before releasing the MMIO bar, so
> that we don't have to care about the consequences of the reset on the
> unload flow.
>
> Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
> Signed-off-by: Alan Previn <alan.previn.teres.alexis@intel.com>
> ---
>   drivers/gpu/drm/i915/gt/uc/intel_gsc_fw.c |  9 +++++
>   drivers/gpu/drm/i915/i915_reg.h           |  3 ++
>   drivers/gpu/drm/i915/intel_uncore.c       | 45 +++++++++++++++++++++++
>   drivers/gpu/drm/i915/intel_uncore.h       | 13 +++++++
>   4 files changed, 70 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_gsc_fw.c b/drivers/gpu/drm/i915/gt/uc/intel_gsc_fw.c
> index 510fb47193ec..5dad3c19c445 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_gsc_fw.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_gsc_fw.c
> @@ -173,6 +173,15 @@ int intel_gsc_fw_upload(struct intel_gsc_uc *gsc)
>   	if (err)
>   		goto fail;
>   
> +	/*
> +	 * Once the GSC FW is loaded, the only way to kill it on driver unload
> +	 * is to do a driver FLR. Given this is a very disruptive action, we
> +	 * want to do it as the last action before releasing the access to the
> +	 * MMIO bar, which means we need to do it as part of the primary uncore
> +	 * cleanup.
> +	 */
> +	intel_uncore_set_flr_on_fini(&gt->i915->uncore);
> +
>   	/* FW is not fully operational until we enable SW proxy */
>   	intel_uc_fw_change_status(gsc_fw, INTEL_UC_FIRMWARE_TRANSFERRED);
>   
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 8e1892d14774..60e55245200b 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -118,6 +118,9 @@
>   
>   #define GU_CNTL				_MMIO(0x101010)
>   #define   LMEM_INIT			REG_BIT(7)
> +#define   DRIVERFLR			REG_BIT(31)
> +#define GU_DEBUG			_MMIO(0x101018)
> +#define   DRIVERFLR_STATUS		REG_BIT(31)
>   
>   #define GEN6_STOLEN_RESERVED		_MMIO(0x1082C0)
>   #define GEN6_STOLEN_RESERVED_ADDR_MASK	(0xFFF << 20)
> diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
> index 8006a6c61466..c1befa33ff59 100644
> --- a/drivers/gpu/drm/i915/intel_uncore.c
> +++ b/drivers/gpu/drm/i915/intel_uncore.c
> @@ -2703,6 +2703,48 @@ void intel_uncore_prune_engine_fw_domains(struct intel_uncore *uncore,
>   	}
>   }
>   
> +static void driver_flr(struct intel_uncore *uncore)
> +{
> +	struct drm_i915_private *i915 = uncore->i915;
> +	const unsigned int flr_timeout_ms = 3000; /* specs recommend a 3s wait */
> +	int ret;
> +
> +	drm_dbg(&i915->drm, "Triggering Driver-FLR\n");
> +
> +	/*
> +	 * Make sure any pending FLR requests have cleared by waiting for the
> +	 * FLR trigger bit to go to zero. Also clear GU_DEBUG's DRIVERFLR_STATUS
> +	 * to make sure it's not still set from a prior attempt (it's a write to
> +	 * clear bit).
> +	 * Note that we should never be in a situation where a previous attempt
> +	 * is still pending (unless the HW is totally dead), but better to be
> +	 * safe in case something unexpected happens
> +	 */
> +	ret = intel_wait_for_register_fw(uncore, GU_CNTL, DRIVERFLR, 0, flr_timeout_ms);
> +	if (ret) {
> +		drm_err(&i915->drm,
> +			"Failed to wait for Driver-FLR bit to clear! %d\n",
> +			ret);
> +		return;
> +	}
> +	intel_uncore_write_fw(uncore, GU_DEBUG, DRIVERFLR_STATUS);
> +
> +	/* Trigger the actual Driver-FLR */
> +	intel_uncore_rmw_fw(uncore, GU_CNTL, 0, DRIVERFLR);
> +
> +	ret = intel_wait_for_register_fw(uncore, GU_DEBUG,
> +					 DRIVERFLR_STATUS, DRIVERFLR_STATUS,
> +					 flr_timeout_ms);
> +	if (ret) {
> +		drm_err(&i915->drm, "wait for Driver-FLR completion failed! %d\n", ret);
> +		return;
> +	}
> +
> +	intel_uncore_write_fw(uncore, GU_DEBUG, DRIVERFLR_STATUS);
> +
> +	return;
> +}
> +
>   /* Called via drm-managed action */
>   void intel_uncore_fini_mmio(struct drm_device *dev, void *data)
>   {
> @@ -2716,6 +2758,9 @@ void intel_uncore_fini_mmio(struct drm_device *dev, void *data)
>   		intel_uncore_fw_domains_fini(uncore);
>   		iosf_mbi_punit_release();
>   	}
> +
> +	if (intel_uncore_needs_flr_on_fini(uncore))
> +		driver_flr(uncore);
>   }
>   
>   /**
> diff --git a/drivers/gpu/drm/i915/intel_uncore.h b/drivers/gpu/drm/i915/intel_uncore.h
> index 5449146a0624..a9fa0b11e7e4 100644
> --- a/drivers/gpu/drm/i915/intel_uncore.h
> +++ b/drivers/gpu/drm/i915/intel_uncore.h
> @@ -153,6 +153,7 @@ struct intel_uncore {
>   #define UNCORE_HAS_FPGA_DBG_UNCLAIMED	BIT(1)
>   #define UNCORE_HAS_DBG_UNCLAIMED	BIT(2)
>   #define UNCORE_HAS_FIFO			BIT(3)
> +#define UNCORE_NEEDS_FLR_ON_FINI	BIT(3)

Dumb mistake, this should be 4 (and that's why the series is failing on 
older gens that don't support the driver FLR). Will wait for comments 
before re-spinning.

Daniele

>   
>   	const struct intel_forcewake_range *fw_domains_table;
>   	unsigned int fw_domains_table_entries;
> @@ -223,6 +224,18 @@ intel_uncore_has_fifo(const struct intel_uncore *uncore)
>   	return uncore->flags & UNCORE_HAS_FIFO;
>   }
>   
> +static inline bool
> +intel_uncore_needs_flr_on_fini(const struct intel_uncore *uncore)
> +{
> +	return uncore->flags & UNCORE_NEEDS_FLR_ON_FINI;
> +}
> +
> +static inline bool
> +intel_uncore_set_flr_on_fini(struct intel_uncore *uncore)
> +{
> +	return uncore->flags |= UNCORE_NEEDS_FLR_ON_FINI;
> +}
> +
>   void intel_uncore_mmio_debug_init_early(struct drm_i915_private *i915);
>   void intel_uncore_init_early(struct intel_uncore *uncore,
>   			     struct intel_gt *gt);