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charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: EAB95160010 X-Stat-Signature: yz19to1dqmswr91d9n99rjana6zjzfs9 X-Rspam-User: X-HE-Tag: 1769446026-544143 X-HE-Meta: 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 w7RXsH7o ewCG14uvOU3fIw1wIQwo2l4pMYLMn5Eei4+JrreEISVRUKtJfRxQl/ClUCVw7H7VX/bi1Kw43WY/F35b/9akV+mBFM80+X5exYP4qiJbATpyixCCMyBN2YbAt/sp5KwK6/lIQqUVbbdBUqaqR2ly0n4hG8gyUk820ZRKsrdtmtWNXLQDQWVGkJEehp65W35A1CZhjtp/OdnD9UT/DdI28muDDw4cLt9lI9m69XZ5KdzTAiM8wL2ePAz4MVHrcQlBHGjpXt4l0yHWonybHNAib/0mEtjSk9KJMhmYryPuylVFH9lofRPkJoBAGNW+wS4LGtUn8ifnPmAnMCpm0VOdw9BkeOXCRKljewANlisc2BX7STVc= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: [ based on kvm/next ]=0A= =0A= Unmapping virtual machine guest memory from the host kernel's direct map=0A= is a successful mitigation against Spectre-style transient execution=0A= issues: if the kernel page tables do not contain entries pointing to=0A= guest memory, then any attempted speculative read through the direct map=0A= will necessarily be blocked by the MMU before any observable=0A= microarchitectural side-effects happen. This means that Spectre-gadgets=0A= and similar cannot be used to target virtual machine memory. Roughly=0A= 60% of speculative execution issues fall into this category [1, Table=0A= 1].=0A= =0A= This patch series extends guest_memfd with the ability to remove its=0A= memory from the host kernel's direct map, to be able to attain the above=0A= protection for KVM guests running inside guest_memfd.=0A= =0A= Additionally, a Firecracker branch with support for these VMs can be=0A= found on GitHub [2].=0A= =0A= For more details, please refer to the v5 cover letter. No substantial=0A= changes in design have taken place since.=0A= =0A= See also related write() syscall support in guest_memfd [3] where=0A= the interoperation between the two features is described.=0A= =0A= Changes since v9:=0A= - Huacai/Ackerley: formatting and error handling fixes=0A= - Heiko: remove TLB flushing from folio_zap_direct_map() on s390=0A= - Willy: set_direct_map_valid_noflush() to take const void * instead of=0A= struct page *page=0A= - Ackerley: remove reject_file_backed variable in=0A= gup_fast_folio_allowed()=0A= - Ackerley: avoid referencing memfd_secret in doc=0A= - Ackerley: make calls to kvm_gmem_folio_zap_direct_map() conditional=0A= to GUEST_MEMFD_FLAG_NO_DIRECT_MAP=0A= - Rick: Exclude TDX from direct map removal=0A= - Rick: Add a comment about current impossibility of zapping at=0A= non-base page granularity.=0A= =0A= v9: https://lore.kernel.org/kvm/20260114134510.1835-1-kalyazin@amazon.com= =0A= v8: https://lore.kernel.org/kvm/20251205165743.9341-1-kalyazin@amazon.com= =0A= v7: https://lore.kernel.org/kvm/20250924151101.2225820-1-patrick.roy@campus= .lmu.de=0A= v6: https://lore.kernel.org/kvm/20250912091708.17502-1-roypat@amazon.co.uk= =0A= v5: https://lore.kernel.org/kvm/20250828093902.2719-1-roypat@amazon.co.uk= =0A= v4: https://lore.kernel.org/kvm/20250221160728.1584559-1-roypat@amazon.co.u= k=0A= RFCv3: https://lore.kernel.org/kvm/20241030134912.515725-1-roypat@amazon.co= .uk=0A= RFCv2: https://lore.kernel.org/kvm/20240910163038.1298452-1-roypat@amazon.c= o.uk=0A= RFCv1: https://lore.kernel.org/kvm/20240709132041.3625501-1-roypat@amazon.c= o.uk=0A= =0A= [1] https://download.vusec.net/papers/quarantine_raid23.pdf=0A= [2] https://github.com/firecracker-microvm/firecracker/tree/feature/secret-= hiding=0A= [3] https://lore.kernel.org/kvm/20251114151828.98165-1-kalyazin@amazon.com= =0A= =0A= Nikita Kalyazin (3):=0A= set_memory: set_direct_map_* to take address=0A= set_memory: add folio_{zap,restore}_direct_map helpers=0A= mm/gup: drop local variable in gup_fast_folio_allowed=0A= =0A= Patrick Roy (12):=0A= mm/gup: drop secretmem optimization from gup_fast_folio_allowed=0A= mm: introduce AS_NO_DIRECT_MAP=0A= KVM: guest_memfd: Add stub for kvm_arch_gmem_invalidate=0A= KVM: x86: define kvm_arch_gmem_supports_no_direct_map()=0A= KVM: arm64: define kvm_arch_gmem_supports_no_direct_map()=0A= KVM: guest_memfd: Add flag to remove from direct map=0A= KVM: selftests: load elf via bounce buffer=0A= KVM: selftests: set KVM_MEM_GUEST_MEMFD in vm_mem_add() if guest_memfd=0A= !=3D -1=0A= KVM: selftests: Add guest_memfd based vm_mem_backing_src_types=0A= KVM: selftests: cover GUEST_MEMFD_FLAG_NO_DIRECT_MAP in existing=0A= selftests=0A= KVM: selftests: stuff vm_mem_backing_src_type into vm_shape=0A= KVM: selftests: Test guest execution from direct map removed gmem=0A= =0A= Documentation/virt/kvm/api.rst | 21 +++--=0A= arch/arm64/include/asm/kvm_host.h | 13 +++=0A= arch/arm64/include/asm/set_memory.h | 9 +-=0A= arch/arm64/mm/pageattr.c | 31 ++++---=0A= arch/loongarch/include/asm/set_memory.h | 9 +-=0A= arch/loongarch/mm/pageattr.c | 37 +++++---=0A= arch/riscv/include/asm/set_memory.h | 9 +-=0A= arch/riscv/mm/pageattr.c | 29 +++++--=0A= arch/s390/include/asm/set_memory.h | 9 +-=0A= arch/s390/mm/pageattr.c | 25 ++++--=0A= arch/x86/include/asm/kvm_host.h | 6 ++=0A= arch/x86/include/asm/set_memory.h | 9 +-=0A= arch/x86/kvm/x86.c | 5 ++=0A= arch/x86/mm/pat/set_memory.c | 43 +++++++---=0A= include/linux/kvm_host.h | 14 ++++=0A= include/linux/pagemap.h | 16 ++++=0A= include/linux/secretmem.h | 18 ----=0A= include/linux/set_memory.h | 19 ++++-=0A= include/uapi/linux/kvm.h | 1 +=0A= kernel/power/snapshot.c | 4 +-=0A= lib/buildid.c | 4 +-=0A= mm/execmem.c | 6 +-=0A= mm/gup.c | 37 +++-----=0A= mm/mlock.c | 2 +-=0A= mm/secretmem.c | 14 ++--=0A= mm/vmalloc.c | 11 ++-=0A= .../testing/selftests/kvm/guest_memfd_test.c | 17 +++-=0A= .../testing/selftests/kvm/include/kvm_util.h | 37 ++++++--=0A= .../testing/selftests/kvm/include/test_util.h | 8 ++=0A= tools/testing/selftests/kvm/lib/elf.c | 8 +-=0A= tools/testing/selftests/kvm/lib/io.c | 23 +++++=0A= tools/testing/selftests/kvm/lib/kvm_util.c | 59 +++++++------=0A= tools/testing/selftests/kvm/lib/test_util.c | 8 ++=0A= tools/testing/selftests/kvm/lib/x86/sev.c | 1 +=0A= .../selftests/kvm/pre_fault_memory_test.c | 1 +=0A= .../selftests/kvm/set_memory_region_test.c | 52 +++++++++++-=0A= .../kvm/x86/private_mem_conversions_test.c | 7 +-=0A= virt/kvm/guest_memfd.c | 84 +++++++++++++++++--=0A= 38 files changed, 511 insertions(+), 195 deletions(-)=0A= =0A= =0A= base-commit: 0499add8efd72456514c6218c062911ccc922a99=0A= -- =0A= 2.50.1=0A= =0A=