linux-kernel - Re: [RFC PATCH v2 2/2] kvm/arm64: Try stage2 block mapping for host device MMIO

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <f1d9f7c2-969f-336a-9744-5706d6c59298@huawei.com>
Date:   Wed, 14 Apr 2021 14:58:40 +0800
From:   Keqian Zhu <zhukeqian1@...wei.com>
To:     Marc Zyngier <maz@...nel.org>
CC:     <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>, <kvm@...r.kernel.org>,
        <kvmarm@...ts.cs.columbia.edu>,
        Mark Rutland <mark.rutland@....com>,
        James Morse <james.morse@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Julien Thierry <julien.thierry.kdev@...il.com>,
        <wanghaibin.wang@...wei.com>
Subject: Re: [RFC PATCH v2 2/2] kvm/arm64: Try stage2 block mapping for host
 device MMIO

Hi Marc,

On 2021/4/8 15:28, Keqian Zhu wrote:
> Hi Marc,
> 
> On 2021/4/7 21:18, Marc Zyngier wrote:
>> On Tue, 16 Mar 2021 13:43:38 +0000,
>> Keqian Zhu <zhukeqian1@...wei.com> wrote:
>>>
[...]

>>>  
>>> +/*
>>> + * Find a mapping size that properly insides the intersection of vma and
>>> + * memslot. And hva and pa have the same alignment to this mapping size.
>>> + * It's rough because there are still other restrictions, which will be
>>> + * checked by the following fault_supports_stage2_huge_mapping().
>>
>> I don't think these restrictions make complete sense to me. If this is
>> a PFNMAP VMA, we should use the biggest mapping size that covers the
>> VMA, and not more than the VMA.
> But as described by kvm_arch_prepare_memory_region(), the memslot may not fully
> cover the VMA. If that's true and we just consider the boundary of the VMA, our
> block mapping may beyond the boundary of memslot. Is this a problem?
emm... Sorry I missed something. The fault_supports_stage2_huge_mapping() will check
the boundary of memslot, so we don't need to check it here. I have send v3, please
check that.

BRs,
Keqian