[PATCH 2/2] drm/i915/gvt: implement override and restore call back for GFX_MODE

[Tian, Kevin]

> From: Chuanxiao Dong
> Sent: Monday, February 27, 2017 5:38 PM
> 
> When host and guest are using different ring submission, host cannot
> use the GFX_MODE register value from guest. So implement the override
> and restore call backs to handle GFX_MODE properly

I feel it might be an overkill to develop a new framework here. In reality
I expect only a few mode registers which we may need special handling.
Then explicitly handling them in one place at end of mmio restoring results
less code and more readability.

> 
> Signed-off-by: Chuanxiao Dong <chuanxiao.dong at intel.com>
> ---
>  drivers/gpu/drm/i915/gvt/render.c | 74
> ++++++++++++++++++++++++++++++++++++---
>  1 file changed, 70 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gvt/render.c b/drivers/gpu/drm/i915/gvt/render.c
> index 7997d70..11f2507 100644
> --- a/drivers/gpu/drm/i915/gvt/render.c
> +++ b/drivers/gpu/drm/i915/gvt/render.c
> @@ -48,8 +48,68 @@ struct render_mmio {
>  	u32 original_bits;
>  };
> 
> +static void render_mmio_override(struct render_mmio *mmio,
> +		u32 *v, u32 mask, u32 override_bits)
> +{
> +	u32 temp_v = *v;
> +
> +	if ((temp_v & mask) == override_bits) {
> +		mmio->override_mask = 0;
> +		mmio->original_bits = 0;
> +		return;
> +	}
> +
> +	/* record which bits are changed */
> +	mmio->original_bits = temp_v & mask;
> +	mmio->override_mask = mask;
> +
> +	/* set the new value */
> +	temp_v &= ~mask;
> +	*v = (temp_v | override_bits);
> +}
> +
> +static void render_mmio_override_gfx_mode(struct render_mmio *mmio, u32 *v)
> +{
> +	u32 mask, override_bits;
> +
> +	if (!v || !mmio)
> +		return;
> +
> +	if (i915.enable_guc_submission) {
> +		mask = GFX_FORWARD_VBLANK_MASK | GFX_INTERRUPT_STEERING;
> +		override_bits = GFX_FORWARD_VBLANK_NEVER |
> +			GFX_INTERRUPT_STEERING;
> +	} else {
> +		mask = GFX_INTERRUPT_STEERING;
> +		override_bits = 0;
> +	}
> +
> +	render_mmio_override(mmio, v, mask, override_bits);
> +}
> +
> +static void render_mmio_restore(struct render_mmio *mmio, u32 *v)
> +{
> +	u32 temp_v;
> +
> +	if (!v || !mmio || !mmio->override_mask)
> +		return;
> +
> +	/*
> +	 * remove the host override bits and
> +	 * restore back the guest mmio
> +	 */
> +	temp_v = *v;
> +	temp_v &= ~mmio->override_mask;
> +	*v = temp_v | mmio->original_bits;
> +
> +	mmio->override_mask = 0;
> +	mmio->original_bits = 0;
> +}
> +
>  static struct render_mmio gen8_render_mmio_list[] = {
> -	{RCS, _MMIO(0x229c), 0xffff, false},
> +	{RCS, _MMIO(0x229c), 0xffff, false,
> +		render_mmio_override_gfx_mode,
> +		render_mmio_restore},
>  	{RCS, _MMIO(0x2248), 0x0, false},
>  	{RCS, _MMIO(0x2098), 0x0, false},
>  	{RCS, _MMIO(0x20c0), 0xffff, true},
> @@ -72,7 +132,9 @@ static struct render_mmio gen8_render_mmio_list[] = {
>  	{RCS, _MMIO(0x7300), 0xffff, true},
>  	{RCS, _MMIO(0x83a4), 0xffff, true},
> 
> -	{BCS, _MMIO(0x2229c), 0xffff, false},
> +	{BCS, _MMIO(0x2229c), 0xffff, false,
> +		render_mmio_override_gfx_mode,
> +		render_mmio_restore},
>  	{BCS, _MMIO(0x2209c), 0xffff, false},
>  	{BCS, _MMIO(0x220c0), 0xffff, false},
>  	{BCS, _MMIO(0x22098), 0x0, false},
> @@ -80,7 +142,9 @@ static struct render_mmio gen8_render_mmio_list[] = {
>  };
> 
>  static struct render_mmio gen9_render_mmio_list[] = {
> -	{RCS, _MMIO(0x229c), 0xffff, false},
> +	{RCS, _MMIO(0x229c), 0xffff, false,
> +		render_mmio_override_gfx_mode,
> +		render_mmio_restore},
>  	{RCS, _MMIO(0x2248), 0x0, false},
>  	{RCS, _MMIO(0x2098), 0x0, false},
>  	{RCS, _MMIO(0x20c0), 0xffff, true},
> @@ -121,7 +185,9 @@ static struct render_mmio gen9_render_mmio_list[] = {
>  	{RCS, _MMIO(0x4df0), 0, false},
>  	{RCS, _MMIO(0x4df4), 0, false},
> 
> -	{BCS, _MMIO(0x2229c), 0xffff, false},
> +	{BCS, _MMIO(0x2229c), 0xffff, false,
> +		render_mmio_override_gfx_mode,
> +		render_mmio_restore},
>  	{BCS, _MMIO(0x2209c), 0xffff, false},
>  	{BCS, _MMIO(0x220c0), 0xffff, false},
>  	{BCS, _MMIO(0x22098), 0x0, false},
> --
> 2.7.4
> 
> 
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