linux-kernel - [PATCH v4 00/21] KVM: selftests: Add Nested NPT support

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Message-ID: <20251230230150.4150236-1-seanjc@google.com>
Date: Tue, 30 Dec 2025 15:01:29 -0800
From: Sean Christopherson <seanjc@...gle.com>
To: Paolo Bonzini <pbonzini@...hat.com>, Marc Zyngier <maz@...nel.org>, 
	Oliver Upton <oupton@...nel.org>, Tianrui Zhao <zhaotianrui@...ngson.cn>, 
	Bibo Mao <maobibo@...ngson.cn>, Huacai Chen <chenhuacai@...nel.org>, 
	Anup Patel <anup@...infault.org>, Paul Walmsley <pjw@...nel.org>, 
	Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>, 
	Christian Borntraeger <borntraeger@...ux.ibm.com>, Janosch Frank <frankja@...ux.ibm.com>, 
	Claudio Imbrenda <imbrenda@...ux.ibm.com>, Sean Christopherson <seanjc@...gle.com>
Cc: kvm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
	kvmarm@...ts.linux.dev, loongarch@...ts.linux.dev, 
	kvm-riscv@...ts.infradead.org, linux-riscv@...ts.infradead.org, 
	linux-kernel@...r.kernel.org, Yosry Ahmed <yosry.ahmed@...ux.dev>
Subject: [PATCH v4 00/21] KVM: selftests: Add Nested NPT support

Yosry's series to add support for nested NPT, and extends vmx_dirty_log_test
and kvm_dirty_log_test (with -n, using memstress) to cover nested SVM.

Note, I'm mildly concerned the last patch to extend nested_dirty_log_test to
validate KVM's handling of READ faults could be flaky, e.g. maybe if someone
is running the test under heavy memory pressure and the to-be-access page is
swapped between the write-from-host and read-from-guest?  But unless someone
knows/shows it'll be flaky, I'm inclined to apply it and hope for the best.

v4:
 - Document the likely reason for setting A/D bits.
 - Put "mmu" structure in common "struct kvm".
 - Make it clear PTE accessors are predicates.
 - Assert that the stage-2 MMU is initialized at most once.
 - Make READABLE a standalone bit (don't overload USER).
 - Don't alias PRESENT => READABLE for EPT.
 - Fix the A/D bit definitions for EPT.
 - Drop the function comment for __tdp_map().
 - Add a patch to extend the nested_dirty_log_test to verify that KVM creates
   writable SPTEs when the gPTEs are writable and dirty.

v3:
 - https://lore.kernel.org/all/20251127013440.3324671-1-yosry.ahmed@linux.dev
 - Dropped the patches that landed in kvm-x86.
 - Reshuffled some patches and cleanups.
 - Introduced kvm_mmu data structures to hold the root, page table
   levels, and page table masks (Sean).
 - Extended memstress as well to cover nested SVM.

v2: https://lore.kernel.org/kvm/20251021074736.1324328-1-yosry.ahmed@linux.dev

Sean Christopherson (7):
  KVM: selftests: Add "struct kvm_mmu" to track a given MMU instance
  KVM: selftests: Plumb "struct kvm_mmu" into x86's MMU APIs
  KVM: selftests: Add a "struct kvm_mmu_arch arch" member to kvm_mmu
  KVM: selftests: Add a stage-2 MMU instance to kvm_vm
  KVM: selftests: Move TDP mapping functions outside of vmx.c
  KVM: selftests: Rename vm_get_page_table_entry() to vm_get_pte()
  KVM: selftests: Test READ=>WRITE dirty logging behavior for shadow MMU

Yosry Ahmed (14):
  KVM: selftests: Make __vm_get_page_table_entry() static
  KVM: selftests: Stop passing a memslot to nested_map_memslot()
  KVM: selftests: Rename nested TDP mapping functions
  KVM: selftests: Kill eptPageTablePointer
  KVM: selftests: Stop setting A/D bits when creating EPT PTEs
  KVM: selftests: Move PTE bitmasks to kvm_mmu
  KVM: selftests: Use a TDP MMU to share EPT page tables between vCPUs
  KVM: selftests: Stop passing VMX metadata to TDP mapping functions
  KVM: selftests: Reuse virt mapping functions for nested EPTs
  KVM: selftests: Allow kvm_cpu_has_ept() to be called on AMD CPUs
  KVM: selftests: Add support for nested NPTs
  KVM: selftests: Set the user bit on nested NPT PTEs
  KVM: selftests: Extend vmx_dirty_log_test to cover SVM
  KVM: selftests: Extend memstress to run on nested SVM

 tools/testing/selftests/kvm/Makefile.kvm      |   2 +-
 .../kvm/include/arm64/kvm_util_arch.h         |   2 +
 .../testing/selftests/kvm/include/kvm_util.h  |  18 +-
 .../kvm/include/loongarch/kvm_util_arch.h     |   1 +
 .../kvm/include/riscv/kvm_util_arch.h         |   1 +
 .../kvm/include/s390/kvm_util_arch.h          |   1 +
 .../selftests/kvm/include/x86/kvm_util_arch.h |  22 ++
 .../selftests/kvm/include/x86/processor.h     |  58 +++-
 .../selftests/kvm/include/x86/svm_util.h      |   9 +
 tools/testing/selftests/kvm/include/x86/vmx.h |  16 +-
 .../selftests/kvm/lib/arm64/processor.c       |  38 +--
 tools/testing/selftests/kvm/lib/kvm_util.c    |  28 +-
 .../selftests/kvm/lib/loongarch/processor.c   |  28 +-
 .../selftests/kvm/lib/riscv/processor.c       |  31 ++-
 .../selftests/kvm/lib/s390/processor.c        |  16 +-
 .../testing/selftests/kvm/lib/x86/memstress.c |  66 +++--
 .../testing/selftests/kvm/lib/x86/processor.c | 237 ++++++++++++----
 tools/testing/selftests/kvm/lib/x86/svm.c     |  24 ++
 tools/testing/selftests/kvm/lib/x86/vmx.c     | 251 ++++-------------
 .../selftests/kvm/x86/hyperv_tlb_flush.c      |   2 +-
 .../selftests/kvm/x86/nested_dirty_log_test.c | 259 ++++++++++++++++++
 .../x86/smaller_maxphyaddr_emulation_test.c   |   4 +-
 .../selftests/kvm/x86/vmx_dirty_log_test.c    | 179 ------------
 .../kvm/x86/vmx_nested_la57_state_test.c      |   2 +-
 24 files changed, 726 insertions(+), 569 deletions(-)
 create mode 100644 tools/testing/selftests/kvm/x86/nested_dirty_log_test.c
 delete mode 100644 tools/testing/selftests/kvm/x86/vmx_dirty_log_test.c


base-commit: 9448598b22c50c8a5bb77a9103e2d49f134c9578
-- 
2.52.0.351.gbe84eed79e-goog