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

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Message-ID: <871f7c8b-0f54-7e9c-4253-b3878b010bbf@intel.com>
Date:   Wed, 15 Mar 2023 19:13:26 +0100
From:   Andrzej Hajda <andrzej.hajda@...el.com>
To:     "Wang, Wei W" <wei.w.wang@...el.com>,
        "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:     "Zhao, Yan Y" <yan.y.zhao@...el.com>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "intel-gfx@...ts.freedesktop.org" <intel-gfx@...ts.freedesktop.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Ben Gardon <bgardon@...gle.com>,
        "intel-gvt-dev@...ts.freedesktop.org" 
        <intel-gvt-dev@...ts.freedesktop.org>
Subject: Re: [Intel-gfx] [PATCH v2 01/27] drm/i915/gvt: Verify pfn is "valid"
 before dereferencing "struct page"

On 13.03.2023 16:37, Wang, Wei W wrote:
> 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;

you can just replace "if (is_error_noslot_pfn(pfn))" with "if 
(!pfn_valid(pfn))", it covers both cases.

Regards
Andrzej