[PATCH v2 2/5] KVM: arm64: Support set the DBM attr during memory abort

[Tian Zheng]

On 2025/11/22 20:54, Marc Zyngier wrote:
> On Fri, 21 Nov 2025 09:23:39 +0000,
> Tian Zheng <zhengtian10 at huawei.com> wrote:
>>
>> From: eillon <yezhenyu2 at huawei.com>
>>
>> Add DBM support to automatically promote write-clean pages to
>> write-dirty, preventing users from being trapped in EL2 due to
>> missing write permissions.
>>
>> Since the DBM attribute was introduced in ARMv8.1 and remains
>> optional in later architecture revisions, including ARMv9.5.
> 
> What is the relevance of this statement?
> 
I will remove this statement in v3.
>>
>> Support set the DBM attr during user_mem_abort().
> 
> I don't think this commit message accurately describes what the code
> does. This merely adds support to the page table code to set the DBM
> bit in the S2 PTE, and nothing else.
> 
Yes, this patch only adds support to set the DBM attr in the S2 PTE
during user_mem_abort(), and does not implement automatic promote
write-clean pages to write-dirty.

I will reward commit message of this patch like:

This patch adds support to set the DBM attr in S2 PTE during
user_mem_abort(). As long as add the DBM bit, it enable hardware
automatically promote write-clean pages to write-dirty, preventing
users from being trapped in EL2 due to missing write permissions.

> 	M.
>