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[v2,0/2] x86: Add the feature Virtual SPEC_CTRL

Message ID 160867624053.3471.7106539070175910424.stgit@bmoger-ubuntu (mailing list archive)
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Series x86: Add the feature Virtual SPEC_CTRL | expand


Babu Moger Dec. 22, 2020, 10:31 p.m. UTC
Newer AMD processors have a feature to virtualize the use of the
SPEC_CTRL MSR on the guest. The series adds the feature support
and enables the feature on SVM.
  NOTE: This is not final yet. Sending out the patches to make
  sure I captured all the comments correctly.

  1. Most of the changes are related to Jim and Sean's feedback.
  2. Improved the description of patch #2.
  3. Updated the vmcb save area's guest spec_ctrl value(offset 0x2E0)
     properly. Initialized during init_vmcb and svm_set_msr and
     returned the value from save area for svm_get_msr.
  4. As Jim commented, transferred the value into the VMCB prior
     to VMRUN and out of the VMCB after #VMEXIT.
  5. Added kvm-unit-test to detect the SPEC CTRL feature.
  6. Sean mantioned of renaming MSR_AMD64_VIRT_SPEC_CTRL. But, it might
     create even more confusion, so dropped the idea for now.



Babu Moger (2):
      x86/cpufeatures: Add the Virtual SPEC_CTRL feature
      KVM: SVM: Add support for Virtual SPEC_CTRL

 arch/x86/include/asm/cpufeatures.h |    1 +
 arch/x86/include/asm/svm.h         |    4 +++-
 arch/x86/kvm/svm/svm.c             |   29 +++++++++++++++++++++++++----
 3 files changed, 29 insertions(+), 5 deletions(-)