[PATCH] drm/i915/gvt: enter failsafe mode when guest requires more resources

[Tian, Kevin]

> From: Min He
> Sent: Wednesday, February 15, 2017 3:34 PM
> 
> Windows guest will notitfy GVTg to request more resources through g2v
> interface, when its resources are not enough.
> This patch is to handle this case and let vgpu enter failsafe mode to
> avoid to many error messages.
> 
> Signed-off-by: Min He <min.he at intel.com>
> Signed-off-by: Pei Zhang <pei.zhang at intel.com>
> ---
>  drivers/gpu/drm/i915/gvt/handlers.c | 15 +++++++++++++++
>  drivers/gpu/drm/i915/i915_pvinfo.h  | 17 +++++++++++++++--
>  2 files changed, 30 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gvt/handlers.c b/drivers/gpu/drm/i915/gvt/handlers.c
> index 6089a1e..50a1850 100644
> --- a/drivers/gpu/drm/i915/gvt/handlers.c
> +++ b/drivers/gpu/drm/i915/gvt/handlers.c
> @@ -1090,6 +1090,21 @@ static int pvinfo_mmio_write(struct intel_vgpu *vgpu,
> unsigned int offset,
>  	case _vgtif_reg(execlist_context_descriptor_lo):
>  	case _vgtif_reg(execlist_context_descriptor_hi):
>  		break;
> +	case _vgtif_reg(min_low_gmadr):
> +		gvt_err("Guest requires %d aperture size!\n", data);
> +		break;
> +	case _vgtif_reg(min_high_gmadr):
> +		gvt_err("Guest requires %d hidden gm size!\n", data);
> +		break;
> +	case _vgtif_reg(min_fence_num):
> +		gvt_err("Guest requires %d fence size!\n", data);
> +		break;

above information is not an obvious error message. at least sth like:

Guest requests more fences which is not supported by this type.

> +	case _vgtif_reg(rs_insufficient):
> +		pr_err("***Guest resource is not enough**********\n");
> +		pr_err("***Please try another vgpu type**********\n");
> +		pr_err("***Entering failsafe mode****************\n");
> +		vgpu->failsafe = true;
> +		break;
>  	default:
>  		gvt_err("invalid pvinfo write offset %x bytes %x data %x\n",
>  				offset, bytes, data);
> diff --git a/drivers/gpu/drm/i915/i915_pvinfo.h b/drivers/gpu/drm/i915/i915_pvinfo.h
> index c0cb297..98a0f18 100644
> --- a/drivers/gpu/drm/i915/i915_pvinfo.h
> +++ b/drivers/gpu/drm/i915/i915_pvinfo.h
> @@ -86,8 +86,21 @@ struct vgt_if {
>  	 */
>  	u32 rsv4;
>  	u32 display_ready;	/* ready for display owner switch */
> -
> -	u32 rsv5[4];
> +	/*
> +	 * driver reported status/error code
> +	 *     0: if the avail_rs is sufficient to driver
> +	 *  Bit 2,1,0 set indicating
> +	 *       Insufficient low_gmadr, high_gmadr, fence resources.
> +	 *  Other bits are reserved.
> +	 */
> +	uint32_t  rs_insufficient;
> +	/*
> +	 * The driver is required to update the following field with minimal
> +	 * required resource size.
> +	 */
> +	uint32_t  min_low_gmadr;
> +	uint32_t  min_high_gmadr;
> +	uint32_t  min_fence_num;

If such operation is not supported, instead of explicitly defining
them and then fail, it's cleaner to keep original definition while
simply fallback to failsafe if any reserved offset is written.

> 
>  	u32 g2v_notify;
>  	u32 rsv6[7];
> --
> 1.9.1
> 
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