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Subject: Re: [RFC] KVM: mm: fd-based approach for supporting KVM guest private
 memory
To:     Joerg Roedel <jroedel@suse.de>
Cc:     Yu Zhang <yu.c.zhang@linux.intel.com>,
        David Hildenbrand <david@redhat.com>,
        Sean Christopherson <seanjc@google.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>, kvm list <kvm@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Borislav Petkov <bp@alien8.de>,
        Andrew Morton <akpm@linux-foundation.org>,
        Andi Kleen <ak@linux.intel.com>,
        David Rientjes <rientjes@google.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        "Peter Zijlstra (Intel)" <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Varad Gautam <varad.gautam@suse.com>,
        Dario Faggioli <dfaggioli@suse.com>,
        the arch/x86 maintainers <x86@kernel.org>,
        linux-mm@kvack.org, linux-coco@lists.linux.dev,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        "Kirill A . Shutemov" <kirill@shutemov.name>,
        Sathyanarayanan Kuppuswamy 
        <sathyanarayanan.kuppuswamy@linux.intel.com>,
        Dave Hansen <dave.hansen@intel.com>
References: <20210824005248.200037-1-seanjc@google.com>
 <307d385a-a263-276f-28eb-4bc8dd287e32@redhat.com>
 <20210827023150.jotwvom7mlsawjh4@linux.intel.com>
 <8f3630ff-bd6d-4d57-8c67-6637ea2c9560@www.fastmail.com>
 <20210901102437.g5wrgezmrjqn3mvy@linux.intel.com>
 <f37a61ba-b7ef-c789-5763-f7f237ae41cc@kernel.org> <YTCZAjdci5yx+n6l@suse.de>
From:   Andy Lutomirski <luto@kernel.org>
Message-ID: <b10b09b0-d5ea-b72a-106a-4e1b0df4dc66@kernel.org>
Date:   Thu, 2 Sep 2021 11:41:53 -0700
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On 9/2/21 2:27 AM, Joerg Roedel wrote:
> On Wed, Sep 01, 2021 at 09:07:59AM -0700, Andy Lutomirski wrote:
>> In principle, you could actually initialize a TDX guest with all of its
>> memory shared and all of it mapped in the host IOMMU.
> 
> Not sure how this works in TDX, but in SEV code fetches are always
> treated as encrypted. So this approach would not work with SEV, not to
> speak about attestation, which will not work with this approach either
> :)
> 

Oof.