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From: Paolo Bonzini <pbonzini@redhat.com>
To: Vitaly Kuznetsov <vkuznets@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: Mon, 27 Jan 2020 18:53:40 +0100
Message-ID: <437c2710-7148-a675-8945-71dc7a90f7dd@redhat.com> (raw)
In-Reply-To: <875zgwnc3w.fsf@vitty.brq.redhat.com>

On 27/01/20 16:38, Vitaly Kuznetsov wrote:
>>> If there are no objections and if we still think it would be beneficial
>>> to minimize the list of controls we filter out (and not go with the full
>>> set like my RFC suggests), I'll prepare v2. (v1, actually, this was RFC).
>> One last idea, can we keep the MSR filtering as is and add the hack in
>> vmx_restore_control_msr()?  That way the (userspace) host and guest see
>> the same values when reading the affected MSRs, and eVMCS wouldn't need
>> it's own hook to do consistency checks.
> Yes but (if I'm not mistaken) we'll have then to keep the filtering we
> currently do in nested_enable_evmcs(): if userspace doesn't do
> KVM_SET_MSR for VMX MSRs (QEMU<4.2) then the filtering in
> vmx_restore_control_msr() won't happen and the guest will see the
> unfiltered set of controls...
> 

Indeed.  The place you used in the RFC is the best we can do, I am afraid.

Paolo


  reply index

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
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 [this message]
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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