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Date:   Tue, 1 Aug 2023 09:45:32 +0800
From:   Yan Zhao <yan.y.zhao@intel.com>
To:     Sean Christopherson <seanjc@google.com>
CC:     Paolo Bonzini <pbonzini@redhat.com>,
        Zhenyu Wang <zhenyuw@linux.intel.com>,
        Zhi Wang <zhi.a.wang@intel.com>, <kvm@vger.kernel.org>,
        <intel-gvt-dev@lists.freedesktop.org>,
        <intel-gfx@lists.freedesktop.org>, <linux-kernel@vger.kernel.org>,
        Yongwei Ma <yongwei.ma@intel.com>,
        Ben Gardon <bgardon@google.com>
Subject: Re: [PATCH v4 07/29] drm/i915/gvt: Error out on an attempt to
 shadowing an unknown GTT entry type
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Reply-To: Yan Zhao <yan.y.zhao@intel.com>
References: <20230729013535.1070024-1-seanjc@google.com>
 <20230729013535.1070024-8-seanjc@google.com>
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Reviewed-by: Yan Zhao <yan.y.zhao@intel.com>

On Fri, Jul 28, 2023 at 06:35:13PM -0700, Sean Christopherson wrote:
> Bail from ppgtt_populate_shadow_entry() if an unexpected GTT entry type
> is encountered instead of subtly falling through to the common "direct
> shadow" path.  Eliminating the default/error path's reliance on the common
> handling will allow hoisting intel_gvt_dma_map_guest_page() into the case
> statements so that the 2MiB case can try intel_gvt_dma_map_guest_page()
> and fallback to splitting the entry on failure.
> 
> Reviewed-by: Zhi Wang <zhi.a.wang@intel.com>
> Tested-by: Yongwei Ma <yongwei.ma@intel.com>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
>  drivers/gpu/drm/i915/gvt/gtt.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/gpu/drm/i915/gvt/gtt.c b/drivers/gpu/drm/i915/gvt/gtt.c
> index 2aed31b497c9..61e38acee2d5 100644
> --- a/drivers/gpu/drm/i915/gvt/gtt.c
> +++ b/drivers/gpu/drm/i915/gvt/gtt.c
> @@ -1306,6 +1306,7 @@ static int ppgtt_populate_shadow_entry(struct intel_vgpu *vgpu,
>  		return -EINVAL;
>  	default:
>  		GEM_BUG_ON(1);
> +		return -EINVAL;
>  	}
>  
>  	/* direct shadow */
> -- 
> 2.41.0.487.g6d72f3e995-goog
>