[PATCH v5 0/8] KVM: SVM: Add Page Modification Logging (PML) support

[Nikunj A Dadhania <nikunj@amd.com>]

This series implements Page Modification Logging (PML) for guests, bringing
hardware-assisted dirty logging support. PML is designed to track guest
modified memory pages. PML enables the hypervisor to identify which pages in a
guest's memory have been modified since the last checkpoint or during live
migration.

The PML feature uses two new VMCB fields (PML_ADDR and PML_INDEX) and
generates a VMEXIT when the 4KB log buffer becomes full.

The feature is enabled by default when hardware support is detected and
can be disabled via the 'pml' module parameter.

Changelog:
v5:
* Rebased on latest kvm/next
* Use EXPORT_SYMBOL_FOR_KVM_INTERNAL (Kai Huang)
* Use cpu_dirty_log_size instead of enable_pml for PML checks, with this patch
  moving enable_pml to common code is not needed (Kai Huang)
* Added SEV PML self test

v4: https://lore.kernel.org/kvm/20251013062515.3712430-1-nikunj@amd.com/
* Add couple of patches to enable_pml and nested CPU dirty logging to
  common code (Kai Huang)
* Rebased to latest kvm/next

v3: https://lore.kernel.org/kvm/20250925101052.1868431-1-nikunj@amd.com/
* Update comments with nested details (Kai Huang)
* Added nested.update_vmcb01_cpu_dirty_logging to update L1 PML (Kai Huang)
* Added patch to use BIT_ULL() instead of BIT() for 64-bit nested_ctl

v2: https://lore.kernel.org/kvm/20250915085938.639049-1-nikunj@amd.com/
* Rebased on latest kvm/next
* Added patch to move pml_pg field from struct vcpu_vmx to struct kvm_vcpu_arch
  to share the PML page. (Kai Huang)
* Dropped the SNP safe allocation optimization patch, will submit it separately.
* Update commit message adding explicit mention that AMD PML follows VMX behavior
  (Kai Huang)
* Updated SNP erratum comment to include PML buffer alongside VMCB, VMSA, and
  AVIC pages. (Kai Huang)

RFC: https://lore.kernel.org/kvm/20250825152009.3512-1-nikunj@amd.com/

Kai Huang (1):
  KVM: x86: Move nested CPU dirty logging logic to common code

Nikunj A Dadhania (7):
  KVM: x86: Carve out PML flush routine
  KVM: x86: Move PML page to common vcpu arch structure
  KVM: VMX: Use cpu_dirty_log_size instead of enable_pml for PML checks
  x86/cpufeatures: Add Page modification logging
  KVM: SVM: Use BIT_ULL for 64-bit nested_ctl bit definitions
  KVM: SVM: Add Page modification logging support
  selftests: KVM: x86: Add SEV PML dirty logging test

 arch/x86/include/asm/cpufeatures.h            |   1 +
 arch/x86/include/asm/kvm_host.h               |   5 +-
 arch/x86/include/asm/svm.h                    |  12 +-
 arch/x86/include/uapi/asm/svm.h               |   2 +
 arch/x86/kernel/cpu/scattered.c               |   1 +
 arch/x86/kvm/kvm_cache_regs.h                 |   7 +
 arch/x86/kvm/svm/nested.c                     |   9 +-
 arch/x86/kvm/svm/sev.c                        |   2 +-
 arch/x86/kvm/svm/svm.c                        |  85 +++++++-
 arch/x86/kvm/svm/svm.h                        |   3 +
 arch/x86/kvm/vmx/main.c                       |   4 +-
 arch/x86/kvm/vmx/nested.c                     |   5 -
 arch/x86/kvm/vmx/vmx.c                        |  71 ++----
 arch/x86/kvm/vmx/vmx.h                        |  10 +-
 arch/x86/kvm/vmx/x86_ops.h                    |   2 +-
 arch/x86/kvm/x86.c                            |  53 ++++-
 arch/x86/kvm/x86.h                            |   8 +
 tools/testing/selftests/kvm/Makefile.kvm      |   1 +
 tools/testing/selftests/kvm/include/x86/sev.h |   4 +
 tools/testing/selftests/kvm/lib/x86/sev.c     |  18 +-
 .../testing/selftests/kvm/x86/sev_pml_test.c  | 203 ++++++++++++++++++
 21 files changed, 422 insertions(+), 84 deletions(-)
 create mode 100644 tools/testing/selftests/kvm/x86/sev_pml_test.c


base-commit: 0499add8efd72456514c6218c062911ccc922a99
-- 
2.48.1