Subject: Re: [PATCH] KVM: x86: Fix the NULL pointer parameter in
 check_cr_write()
To: Paolo Bonzini <pbonzini@redhat.com>, Jim Mattson <jmattson@google.com>,
        David Hildenbrand <david@redhat.com>
Cc: kvm list <kvm@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>,
        =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= <rkrcmar@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
        "H . Peter Anvin" <hpa@zytor.com>
References: <1505731501-6821-1-git-send-email-yu.c.zhang@linux.intel.com>
 <62dd03f0-4049-1d9c-d07b-61cac4c49c93@redhat.com>
 <CALMp9eS3X3owa7ue5+jpz8bi-Sgp5MWGTj7DvFMLWBqErgDNOg@mail.gmail.com>
 <0a2a586b-5dd6-88cb-bd22-f0676b1c8fbe@linux.intel.com>
 <0f652327-03f4-5fba-0717-d1f29e45d6cf@redhat.com>
From: Yu Zhang <yu.c.zhang@linux.intel.com>
Message-ID: <b44d8759-d2e9-88ea-7693-2c6e877f13d7@linux.intel.com>
Date: Wed, 20 Sep 2017 16:27:16 +0800
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101
 Thunderbird/52.3.0
MIME-Version: 1.0
In-Reply-To: <0f652327-03f4-5fba-0717-d1f29e45d6cf@redhat.com>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 7bit
Content-Language: en-US
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 679
Lines: 20


On 9/20/2017 4:13 PM, Paolo Bonzini wrote:
> On 20/09/2017 08:35, Yu Zhang wrote:
>> 2 reasons I did not choose to change kvm_cpuid(): 1> like Jim's
>> comments, kvm_cpuid() will eventually write the *eax - *edx no
>> matter a cpuid entry is found or not; 2> currently, return value of
>> kvm_cpuid() is either true when an entry is found or false otherwise.
>> We can change kvm_cpuid() to check the pointers of GPRs against NULL
>> and return false immediately. Then the false value would have 2
>> different meanings - entry not found, or invalid params.
>>
>> Paolo, any suggestion? :-)
> Radim, has already sent this version to Linus. :)

Got it. Thanks. :)

Yu
> Paolo
>