linux-kernel - Re: [PATCH] KVM: x86/mmu: Add "never" option to allow sticky disabling of nx_huge

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Message-ID: <168667299355.1927151.1998349801097712999.b4-ty@google.com>
Date:   Tue, 13 Jun 2023 16:21:52 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Li RongQing <lirongqing@...du.com>,
        Yong He <zhuangel570@...il.com>,
        Robert Hoo <robert.hoo.linux@...il.com>,
        Kai Huang <kai.huang@...el.com>,
        Luiz Capitulino <luizcap@...zon.com>
Subject: Re: [PATCH] KVM: x86/mmu: Add "never" option to allow sticky
 disabling of nx_huge_pages

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 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