Message-ID: <65e1f2ca-5d89-d67f-2e0e-542094f89f05@redhat.com>
Date:   Thu, 18 Nov 2021 16:01:25 +0100
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101
 Thunderbird/91.2.0
Subject: Re: [PATCH 15/15] KVM: X86: Always set gpte_is_8_bytes when direct
 map
Content-Language: en-US
To:     Lai Jiangshan <laijs@linux.alibaba.com>,
        Lai Jiangshan <jiangshanlai@gmail.com>,
        linux-kernel@vger.kernel.org
Cc:     kvm@vger.kernel.org, Jonathan Corbet <corbet@lwn.net>,
        Sean Christopherson <seanjc@google.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>, x86@kernel.org,
        "H. Peter Anvin" <hpa@zytor.com>, linux-doc@vger.kernel.org
References: <20211118110814.2568-1-jiangshanlai@gmail.com>
 <20211118110814.2568-16-jiangshanlai@gmail.com>
 <16b701db-e277-c4ef-e198-65a2dc6e3fdf@redhat.com>
 <bcfa0e4d-f6ab-037a-9ce1-d0cd612422a5@linux.alibaba.com>
From:   Paolo Bonzini <pbonzini@redhat.com>
In-Reply-To: <bcfa0e4d-f6ab-037a-9ce1-d0cd612422a5@linux.alibaba.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit
Precedence: bulk

On 11/18/21 15:34, Lai Jiangshan wrote:
> 
> 
> On 2021/11/18 19:12, Paolo Bonzini wrote:
>> On 11/18/21 12:08, Lai Jiangshan wrote:
>>> From: Lai Jiangshan <laijs@linux.alibaba.com>
>>>
>>> When direct map, gpte_is_8_bytes has no meaning, but it is true for all
>>> other cases except direct map when nonpaping.
>>>
>>> Setting gpte_is_8_bytes to true when nonpaping can ensure that
>>> !gpte_is_8_bytes means 32-bit gptes for shadow paging.
>>
>> Then the right thing to do would be to rename it to has_4_byte_gptes 
>> and invert the direction.  But as things stand, it's a bit more 
>> confusing to make gpte_is_8_bytes=1 if there are no guest PTEs at all.
>>
> 
> I will make the last 3 patches be a separated patchset and will do the 
> rename.

Patches 13 and 14 are fine actually.

Paolo