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Date:   Fri, 16 Apr 2021 17:46:02 +0100
From:   Matthew Wilcox <willy@infradead.org>
To:     "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc:     Dave Hansen <dave.hansen@linux.intel.com>,
        Andy Lutomirski <luto@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Sean Christopherson <seanjc@google.com>,
        Jim Mattson <jmattson@google.com>,
        David Rientjes <rientjes@google.com>,
        "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>,
        "Kleen, Andi" <andi.kleen@intel.com>,
        "Yamahata, Isaku" <isaku.yamahata@intel.com>,
        Erdem Aktas <erdemaktas@google.com>,
        Steve Rutherford <srutherford@google.com>,
        Peter Gonda <pgonda@google.com>,
        David Hildenbrand <david@redhat.com>, x86@kernel.org,
        kvm@vger.kernel.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Subject: Re: [RFCv2 00/13] TDX and guest memory unmapping
Message-ID: <20210416164602.GN2531743@casper.infradead.org>
References: <20210416154106.23721-1-kirill.shutemov@linux.intel.com>
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On Fri, Apr 16, 2021 at 06:40:53PM +0300, Kirill A. Shutemov wrote:
> TDX integrity check failures may lead to system shutdown host kernel must
> not allow any writes to TD-private memory. This requirment clashes with
> KVM design: KVM expects the guest memory to be mapped into host userspace
> (e.g. QEMU).
> 
> This patchset aims to start discussion on how we can approach the issue.
> 
> The core of the change is in the last patch. Please see more detailed
> description of the issue and proposoal of the solution there.

This seems to have some parallels with s390's arch_make_page_accessible().
Is there any chance to combine the two, so we don't end up with duplicated
hooks all over the MM for this kind of thing?

https://patchwork.kernel.org/project/kvm/cover/20200214222658.12946-1-borntraeger@de.ibm.com/

and recent THP/Folio-related discussion:
https://lore.kernel.org/linux-mm/20210409194059.GW2531743@casper.infradead.org/