From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>,
Sean Christopherson <sean.j.christopherson@intel.com>
Cc: kvm@vger.kernel.org, Jim Mattson <jmattson@google.com>,
linux-kernel@vger.kernel.org, Liran Alon <liran.alon@oracle.com>,
Roman Kagan <rkagan@virtuozzo.com>
Subject: Re: [PATCH RFC 2/3] x86/kvm/hyper-v: move VMX controls sanitization out of nested_enable_evmcs()
Date: Thu, 23 Jan 2020 10:15:41 +0100 [thread overview]
Message-ID: <87zheer0si.fsf@vitty.brq.redhat.com> (raw)
In-Reply-To: <f15d9e98-25e9-2031-2db5-6aaa6c78c0eb@redhat.com>
Paolo Bonzini <pbonzini@redhat.com> writes:
> On 22/01/20 17:29, Vitaly Kuznetsov wrote:
>> Yes, in case we're back to the idea to filter things out in QEMU we can
>> do this. What I don't like is that every other userspace which decides
>> to enable eVMCS will have to perform the exact same surgery as in case
>> it sets allow_unsupported_controls=0 it'll have to know (hardcode) the
>> filtering (or KVM_SET_MSRS will fail) and in case it opts for
>> allow_unsupported_controls=1 Windows guests just won't boot without the
>> filtering.
>>
>> It seems to be 1:1, eVMCSv1 requires the filter.
>
> Yes, that's the point. It *is* a hack in KVM, but it is generally
> preferrable to have an easier API for userspace, if there's only one way
> to do it.
>
> Though we could be a bit more "surgical" and only remove
> SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES---thus minimizing the impact on
> non-eVMCS guests. Vitaly, can you prepare a v2 that does that and adds
> a huge "hack alert" comment that explains the discussion?
Yes, sure. I'd like to do more testing to make sure filtering out
SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES is enough for other Hyper-V
versions too (who knows how many bugs are there :-)
--
Vitaly
next prev parent reply other threads:[~2020-01-23 9:15 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-15 17:10 [PATCH RFC 0/3] x86/kvm/hyper-v: fix enlightened VMCS & QEMU4.2 Vitaly Kuznetsov
2020-01-15 17:10 ` [PATCH RFC 1/3] x86/kvm/hyper-v: remove stale evmcs_already_enabled check from nested_enable_evmcs() Vitaly Kuznetsov
2020-01-15 22:50 ` Liran Alon
2020-01-15 17:10 ` [PATCH RFC 2/3] x86/kvm/hyper-v: move VMX controls sanitization out of nested_enable_evmcs() Vitaly Kuznetsov
2020-01-15 22:49 ` Liran Alon
2020-01-16 8:37 ` Vitaly Kuznetsov
2020-02-03 15:11 ` Vitaly Kuznetsov
2020-01-15 23:27 ` Sean Christopherson
2020-01-15 23:30 ` Liran Alon
2020-01-16 8:51 ` Vitaly Kuznetsov
2020-01-16 16:19 ` Sean Christopherson
2020-01-16 16:57 ` Vitaly Kuznetsov
2020-01-17 6:31 ` Sean Christopherson
2020-01-18 21:42 ` Paolo Bonzini
2020-01-19 8:54 ` Paolo Bonzini
2020-01-22 5:47 ` Sean Christopherson
2020-01-22 9:37 ` Vitaly Kuznetsov
2020-01-22 14:33 ` Paolo Bonzini
2020-01-22 15:08 ` Vitaly Kuznetsov
2020-01-22 15:51 ` Sean Christopherson
2020-01-22 16:29 ` Vitaly Kuznetsov
2020-01-22 16:40 ` Paolo Bonzini
2020-01-23 9:15 ` Vitaly Kuznetsov [this message]
2020-01-23 19:09 ` Vitaly Kuznetsov
2020-01-24 17:25 ` Sean Christopherson
2020-01-27 15:38 ` Vitaly Kuznetsov
2020-01-27 17:53 ` Paolo Bonzini
2020-01-27 21:52 ` Vitaly Kuznetsov
2020-01-27 18:17 ` Sean Christopherson
2020-01-15 17:10 ` [PATCH RFC 3/3] x86/kvm/hyper-v: don't allow to turn on unsupported VMX controls for nested guests Vitaly Kuznetsov
2020-01-15 22:59 ` Liran Alon
2020-01-16 8:55 ` Vitaly Kuznetsov
2020-01-16 16:21 ` Sean Christopherson
2020-01-19 8:57 ` Paolo Bonzini
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