linux-kernel - [RFCv1 0/7] TDX and guest memory unmapping

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Date:   Fri,  2 Apr 2021 18:26:38 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Sean Christopherson <seanjc@...gle.com>,
        Jim Mattson <jmattson@...gle.com>
Cc:     David Rientjes <rientjes@...gle.com>,
        "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>,
        "Kleen, Andi" <andi.kleen@...el.com>,
        "Yamahata, Isaku" <isaku.yamahata@...el.com>, x86@...nel.org,
        kvm@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: [RFCv1 0/7] TDX and guest memory unmapping

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.

The patchset can also be found here:

git://git.kernel.org/pub/scm/linux/kernel/git/kas/linux.git kvm-unmapped-poison

Kirill A. Shutemov (7):
  x86/mm: Move force_dma_unencrypted() to common code
  x86/kvm: Introduce KVM memory protection feature
  x86/kvm: Make DMA pages shared
  x86/kvm: Use bounce buffers for KVM memory protection
  x86/kvmclock: Share hvclock memory with the host
  x86/realmode: Share trampoline area if KVM memory protection enabled
  KVM: unmap guest memory using poisoned pages

 arch/x86/Kconfig                     |   9 +-
 arch/x86/include/asm/cpufeatures.h   |   1 +
 arch/x86/include/asm/io.h            |   4 +-
 arch/x86/include/asm/kvm_para.h      |   5 +
 arch/x86/include/asm/mem_encrypt.h   |   7 +-
 arch/x86/include/uapi/asm/kvm_para.h |   3 +-
 arch/x86/kernel/kvm.c                |  20 ++++
 arch/x86/kernel/kvmclock.c           |   2 +-
 arch/x86/kernel/pci-swiotlb.c        |   3 +-
 arch/x86/kvm/Kconfig                 |   1 +
 arch/x86/kvm/cpuid.c                 |   3 +-
 arch/x86/kvm/mmu/mmu.c               |  15 ++-
 arch/x86/kvm/mmu/paging_tmpl.h       |  10 +-
 arch/x86/kvm/x86.c                   |   6 +
 arch/x86/mm/Makefile                 |   2 +
 arch/x86/mm/mem_encrypt.c            |  74 ------------
 arch/x86/mm/mem_encrypt_common.c     |  87 ++++++++++++++
 arch/x86/mm/pat/set_memory.c         |  10 ++
 arch/x86/realmode/init.c             |   7 +-
 include/linux/kvm_host.h             |  12 ++
 include/linux/swapops.h              |  20 ++++
 include/uapi/linux/kvm_para.h        |   5 +-
 mm/gup.c                             |  31 +++--
 mm/memory.c                          |  45 +++++++-
 mm/page_vma_mapped.c                 |   8 +-
 mm/rmap.c                            |   2 +-
 mm/shmem.c                           |   7 ++
 virt/kvm/Kconfig                     |   3 +
 virt/kvm/kvm_main.c                  | 164 ++++++++++++++++++++++++---
 29 files changed, 442 insertions(+), 124 deletions(-)
 create mode 100644 arch/x86/mm/mem_encrypt_common.c

-- 
2.26.3