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Re: [PATCH v4 16/21] i386: track explicit 'hv-*' features enablement/dis
From: |
Vitaly Kuznetsov |
Subject: |
Re: [PATCH v4 16/21] i386: track explicit 'hv-*' features enablement/disablement |
Date: |
Fri, 12 Feb 2021 09:45:52 +0100 |
Igor Mammedov <imammedo@redhat.com> writes:
> On Wed, 10 Feb 2021 17:40:28 +0100
> Vitaly Kuznetsov <vkuznets@redhat.com> wrote:
>
>> Sometimes we'd like to know which features were explicitly enabled and which
>> were explicitly disabled on the command line. E.g. it seems logical to handle
>> 'hv_passthrough,hv_feature=off' as "enable everything supported by the host
>> except for hv_feature" but this doesn't seem to be possible with the current
>> 'hyperv_features' bit array. Introduce 'hv_features_on'/'hv_features_off'
>> add-ons and track explicit enablement/disablement there.
>>
>> Note, it doesn't seem to be possible to fill 'hyperv_features' array during
>> CPU creation time when 'hv-passthrough' is specified and we're running on
>> an older kernel without KVM_CAP_SYS_HYPERV_CPUID support. To get the list
>> of the supported Hyper-V features we need to actually create KVM VCPU and
>> this happens much later.
>
> seems to me that we are returning back to +-feat parsing, this time only for
> hyperv.
> I'm not sure I like it back, especially considering we are going to
> drop "-feat" priority for x86.
>
> now about impossible, see arm/kvm/virt, they create a 'sample' VCPU at KVM
> init time to probe for some CPU features in advance. You can use similar
> approach to prepare value for hyperv_features.
>
KVM_CAP_SYS_HYPERV_CPUID is supported since 5.11 and eventually it'll
make it to all kernels we care about so I'd really like to avoid any
'sample' CPUs for the time being. On/off parsing looks like a much
lesser evil.
--
Vitaly
- [PATCH v4 08/21] i386: introduce hv_cpuid_cache, (continued)
- [PATCH v4 08/21] i386: introduce hv_cpuid_cache, Vitaly Kuznetsov, 2021/02/10
- [PATCH v4 09/21] i386: split hyperv_handle_properties() into hyperv_expand_features()/hyperv_fill_cpuids(), Vitaly Kuznetsov, 2021/02/10
- [PATCH v4 05/21] i386: introduce hyperv_feature_supported(), Vitaly Kuznetsov, 2021/02/10
- [PATCH v4 06/21] i386: introduce hv_cpuid_get_host(), Vitaly Kuznetsov, 2021/02/10
- [PATCH v4 11/21] i386: switch hyperv_expand_features() to using error_setg(), Vitaly Kuznetsov, 2021/02/10
- [PATCH v4 12/21] i386: adjust the expected KVM_GET_SUPPORTED_HV_CPUID array size, Vitaly Kuznetsov, 2021/02/10
- [PATCH v4 10/21] i386: move eVMCS enablement to hyperv_init_vcpu(), Vitaly Kuznetsov, 2021/02/10
- [PATCH v4 13/21] i386: prefer system KVM_GET_SUPPORTED_HV_CPUID ioctl over vCPU's one, Vitaly Kuznetsov, 2021/02/10
- [PATCH v4 16/21] i386: track explicit 'hv-*' features enablement/disablement, Vitaly Kuznetsov, 2021/02/10
- Re: [PATCH v4 16/21] i386: track explicit 'hv-*' features enablement/disablement, Igor Mammedov, 2021/02/11
- Re: [PATCH v4 16/21] i386: track explicit 'hv-*' features enablement/disablement,
Vitaly Kuznetsov <=
- Re: [PATCH v4 16/21] i386: track explicit 'hv-*' features enablement/disablement, Igor Mammedov, 2021/02/12
- Re: [PATCH v4 16/21] i386: track explicit 'hv-*' features enablement/disablement, Vitaly Kuznetsov, 2021/02/12
- Re: [PATCH v4 16/21] i386: track explicit 'hv-*' features enablement/disablement, Vitaly Kuznetsov, 2021/02/12
- Re: [PATCH v4 16/21] i386: track explicit 'hv-*' features enablement/disablement, Igor Mammedov, 2021/02/12
- Re: [PATCH v4 16/21] i386: track explicit 'hv-*' features enablement/disablement, Vitaly Kuznetsov, 2021/02/15
- Re: [PATCH v4 16/21] i386: track explicit 'hv-*' features enablement/disablement, Igor Mammedov, 2021/02/15
- Re: [PATCH v4 16/21] i386: track explicit 'hv-*' features enablement/disablement, Igor Mammedov, 2021/02/15
- Re: [PATCH v4 16/21] i386: track explicit 'hv-*' features enablement/disablement, Vitaly Kuznetsov, 2021/02/15
- Re: [PATCH v4 16/21] i386: track explicit 'hv-*' features enablement/disablement, Igor Mammedov, 2021/02/12
- Re: [PATCH v4 16/21] i386: track explicit 'hv-*' features enablement/disablement, Vitaly Kuznetsov, 2021/02/15