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Message-ID: <abf509a2-ebfd-7b5f-4f7a-fdd4ef60c1de@amazon.com>
Date:   Wed, 14 Jun 2023 09:20:24 -0400
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Subject: Re: [PATCH] KVM: x86/mmu: Add "never" option to allow sticky
 disabling of nx_huge_pages
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To:     Sean Christopherson <seanjc@google.com>,
        Paolo Bonzini <pbonzini@redhat.com>
CC:     <kvm@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        Li RongQing <lirongqing@baidu.com>,
        Yong He <zhuangel570@gmail.com>,
        Robert Hoo <robert.hoo.linux@gmail.com>,
        Kai Huang <kai.huang@intel.com>
References: <20230602005859.784190-1-seanjc@google.com>
 <168667299355.1927151.1998349801097712999.b4-ty@google.com>
From:   Luiz Capitulino <luizcap@amazon.com>
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On 2023-06-13 19:21, Sean Christopherson wrote:

> 
> 
> 
> On Thu, 01 Jun 2023 17:58:59 -0700, Sean Christopherson wrote:
>> Add a "never" option to the nx_huge_pages module param to allow userspace
>> to do a one-way hard disabling of the mitigation, and don't create the
>> per-VM recovery threads when the mitigation is hard disabled.  Letting
>> userspace pinky swear that userspace doesn't want to enable NX mitigation
>> (without reloading KVM) allows certain use cases to avoid the latency
>> problems associated with spawning a kthread for each VM.
>>
>> [...]
> 
> Applied to kvm-x86 mmu.  I kept the default as "auto" for now, as that can go on
> top and I don't want to introduce that change this late in the cycle.  If no one
> beats me to the punch (hint, hint ;-) ), I'll post a patch to make "never" the
> default for unaffected hosts so that we can discuss/consider that change for 6.6.

Thanks Sean, I agree with the plan. I could give a try on the patch if you'd like.

- Luiz

> 
> Thanks for the reviews!
> 
> [1/1] KVM: x86/mmu: Add "never" option to allow sticky disabling of nx_huge_pages
>        https://github.com/kvm-x86/linux/commit/0b210faf3373
> 
> --
> https://github.com/kvm-x86/linux/tree/next
> https://github.com/kvm-x86/linux/tree/fixes