[PATCH v4 0/7] 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:
v4:
* Add couple of patches to enable_pml and nested CPU dirty logging to
  common code (Kai Huang)
* Rebased to latest kvm/next

v3:
* 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 (6):
  KVM: x86: Carve out PML flush routine
  KVM: x86: Move PML page to common vcpu arch structure
  KVM: x86: Move enable_pml variable to common x86 code
  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

 arch/x86/include/asm/cpufeatures.h |  1 +
 arch/x86/include/asm/kvm_host.h    |  6 ++-
 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             | 84 +++++++++++++++++++++++++++++-
 arch/x86/kvm/svm/svm.h             |  2 +
 arch/x86/kvm/vmx/main.c            |  4 +-
 arch/x86/kvm/vmx/nested.c          |  5 --
 arch/x86/kvm/vmx/vmx.c             | 72 ++++++-------------------
 arch/x86/kvm/vmx/vmx.h             | 10 +---
 arch/x86/kvm/vmx/x86_ops.h         |  2 +-
 arch/x86/kvm/x86.c                 | 56 +++++++++++++++++++-
 arch/x86/kvm/x86.h                 |  8 +++
 17 files changed, 201 insertions(+), 82 deletions(-)


base-commit: 6b36119b94d0b2bb8cea9d512017efafd461d6ac
-- 
2.48.1