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Date:   Tue, 4 May 2021 20:33:49 +0000
From:   Sean Christopherson <seanjc@google.com>
To:     Paolo Bonzini <pbonzini@redhat.com>
Cc:     linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
        srutherford@google.com, joro@8bytes.org, brijesh.singh@amd.com,
        thomas.lendacky@amd.com, ashish.kalra@amd.com,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>, Borislav Petkov <bp@suse.de>,
        x86@kernel.org
Subject: Re: [PATCH v3 2/2] KVM: X86: Introduce KVM_HC_PAGE_ENC_STATUS
 hypercall
Message-ID: <YJGvrYWLQwiRSNLt@google.com>
References: <20210429104707.203055-1-pbonzini@redhat.com>
 <20210429104707.203055-3-pbonzini@redhat.com>
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 <c4bf8a05-ec0d-9723-bb64-444fe1f088b5@redhat.com>
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 <f7300393-6527-005f-d824-eed5f7f2f8a8@redhat.com>
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On Tue, May 04, 2021, Paolo Bonzini wrote:
> On 04/05/21 19:09, Sean Christopherson wrote:
> > On Sat, May 01, 2021, Paolo Bonzini wrote:
> > > - make it completely independent from migration, i.e. it's just a facet of
> > > MSR_KVM_PAGE_ENC_STATUS saying whether the bitmap is up-to-date.  It would
> > > use CPUID bit as the encryption status bitmap and have no code at all in KVM
> > > (userspace needs to set up the filter and implement everything).
> > 
> > If the bit is purely a "page encryption status is up-to-date", what about
> > overloading KVM_HC_PAGE_ENC_STATUS to handle that status update as well?   That
> > would eliminate my biggest complaint about having what is effectively a single
> > paravirt feature split into two separate, but intertwined chunks of ABI.
> 
> It's true that they are intertwined, but I dislike not having a way to read
> the current state.

From the guest?