linux-kernel - RE: [PATCH v2 01/27] drm/i915/gvt: Verify pfn is "valid" before dereferencing "struct page"

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Date:   Mon, 13 Mar 2023 15:37:21 +0000
From:   "Wang, Wei W" <wei.w.wang@...el.com>
To:     "Christopherson,, Sean" <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Zhenyu Wang <zhenyuw@...ux.intel.com>,
        "Wang, Zhi A" <zhi.a.wang@...el.com>
CC:     "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "intel-gvt-dev@...ts.freedesktop.org" 
        <intel-gvt-dev@...ts.freedesktop.org>,
        "intel-gfx@...ts.freedesktop.org" <intel-gfx@...ts.freedesktop.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Zhao, Yan Y" <yan.y.zhao@...el.com>,
        Ben Gardon <bgardon@...gle.com>
Subject: RE: [PATCH v2 01/27] drm/i915/gvt: Verify pfn is "valid" before
 dereferencing "struct page"

On Saturday, March 11, 2023 8:23 AM, Sean Christopherson wrote:
> diff --git a/drivers/gpu/drm/i915/gvt/gtt.c b/drivers/gpu/drm/i915/gvt/gtt.c
> index 4ec85308379a..58b9b316ae46 100644
> --- a/drivers/gpu/drm/i915/gvt/gtt.c
> +++ b/drivers/gpu/drm/i915/gvt/gtt.c
> @@ -1183,6 +1183,10 @@ static int is_2MB_gtt_possible(struct intel_vgpu
> *vgpu,
>  	pfn = gfn_to_pfn(vgpu->vfio_device.kvm, ops->get_pfn(entry));
>  	if (is_error_noslot_pfn(pfn))
>  		return -EINVAL;
> +
> +	if (!pfn_valid(pfn))
> +		return -EINVAL;
> +

Merge the two errors in one "if" to have less LOC?
i.e.
if (is_error_noslot_pfn(pfn) || !pfn_valid(pfn))
    return -EINVAL;