From mboxrd@z Thu Jan  1 00:00:00 1970
From: Vitaly Kuznetsov <vkuznets@redhat.com>
Subject: Re: [PATCH v2 6/6] KVM: nVMX: optimize prepare_vmcs02{,_full} for Enlightened VMCS case
Date: Wed, 25 Jul 2018 16:13:12 +0200
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Cc: kvm@vger.kernel.org,
        Radim =?utf-8?B?S3LEjW3DocWZ?= <rkrcmar@redhat.com>,
        Roman Kagan <rkagan@virtuozzo.com>,
        "K. Y. Srinivasan" <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        Stephen Hemminger <sthemmin@microsoft.com>,
        "Michael Kelley \(EOSG\)" <Michael.H.Kelley@microsoft.com>,
        Mohammed Gamal <mmorsy@redhat.com>,
        Cathy Avery <cavery@redhat.com>, linux-kernel@vger.kernel.org,
        Jim Mattson <jmattson@google.com>,
        Liran Alon <liran.alon@oracle.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Return-path: <linux-kernel-owner@vger.kernel.org>
In-Reply-To: <2ed3d00b-bc99-2e2d-3a23-a86de767bfec@redhat.com> (Paolo
        Bonzini's message of "Wed, 25 Jul 2018 15:31:47 +0200")
Sender: linux-kernel-owner@vger.kernel.org
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Paolo Bonzini <pbonzini@redhat.com> writes:

> On 25/07/2018 15:26, Vitaly Kuznetsov wrote:
>
>> The other place where we set dirty_vmcs12 is the newly introduced
>> vmx_set_nested_state() but I think I'm going to add support for eVMCS
>> there later and just return something like -ENOTSUPP for now. Too many
>> people work on nested simultaneously :-)
>
> Hmm, I think that means you have to put the clean fields in the
> vmx_nested struct.  Then it's really easy in vmx_set_nested_state to
> clear all the clean bits.  Touching memory in vmx_set_nested_state is...
> *puts on sunglasses* a touchy subject (see comment in kvm/queue's
> enter_vmx_non_root_mode).
>

Not only clean fields, in case we can't touch memory in
vmx_set_nested_state I guess we'll need to cache the whole eVMCS, just
like we save cached_shadow_vmcs12. Anyway, let's eat the elephant one
bite at a time :-)

-- 
  Vitaly