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SubjectRe: [PATCH 1/3] KVM: X86: Add "nopvspin" parameter to disable PV spinlocks
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On 2019/9/30 23:41, Vitaly Kuznetsov wrote:
> Zhenzhong Duan<zhenzhong.duan@oracle.com> writes:
>
>> There are cases where a guest tries to switch spinlocks to bare metal
>> behavior (e.g. by setting "xen_nopvspin" on XEN platform and
>> "hv_nopvspin" on HYPER_V).
>>
>> That feature is missed on KVM, add a new parameter "nopvspin" to disable
>> PV spinlocks for KVM guest.
>>
>> This new parameter is also intended to replace "xen_nopvspin" and
>> "hv_nopvspin" in the future.
> Any reason to not do it right now? We will probably need to have compat
> code to support xen_nopvspin/hv_nopvspin too but emit a 'is deprecated'
> warning.

Sorry the description isn't clear, I'll fix it.

I did the compat work in the other two patches.
[PATCH 2/3] xen: Mark "xen_nopvspin" parameter obsolete and map it to "nopvspin"
[PATCH 3/3] x86/hyperv: Mark "hv_nopvspin" parameter obsolete and map it to "nopvspin"

>
>> The global variable pvspin isn't defined as __initdata as it's used at
>> runtime by XEN guest.
>>
>> Refactor the print stuff with pr_* which is preferred.
> Please do it in a separate patch.

Ok, I'll do that in v2. Thanks for review.

Zhenzhong

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