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From:   Andy Lutomirski <luto@amacapital.net>
Date:   Wed, 12 Feb 2020 21:42:02 -0800
Message-ID: <CALCETrX6Oo00NXn2QfR=eOKD9wvWiov_=WBRwb7V266=hJ2Duw@mail.gmail.com>
Subject: Re: [PATCH 10/12] mm: x86: Invoke hypercall when page encryption
 status is changed
To:     Ashish Kalra <Ashish.Kalra@amd.com>
Cc:     Paolo Bonzini <pbonzini@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Radim Krcmar <rkrcmar@redhat.com>,
        Joerg Roedel <joro@8bytes.org>, Borislav Petkov <bp@suse.de>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        David Rientjes <rientjes@google.com>, X86 ML <x86@kernel.org>,
        kvm list <kvm@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>
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On Wed, Feb 12, 2020 at 5:18 PM Ashish Kalra <Ashish.Kalra@amd.com> wrote:
>
> From: Brijesh Singh <brijesh.singh@amd.com>
>
> Invoke a hypercall when a memory region is changed from encrypted ->
> decrypted and vice versa. Hypervisor need to know the page encryption
> status during the guest migration.

What happens if the guest memory status doesn't match what the
hypervisor thinks it is?  What happens if the guest gets migrated
between the hypercall and the associated flushes?