[PATCH v3 0/8] KVM: VMX/SVM: use the same SPEC_CTRL assembly code

[Paolo Bonzini <pbonzini@redhat.com>]

As discussed in the APX thread, this series moves the SPEC_CTRL
handling for VMX entirely to vmenter.S, and while at it improves
the code reuse between SVM and VMX.

The prototype of __vmx_vcpu_run() and __svm_vcpu_run() becomes
the same, with a set of bit flags for the second argument (which
can be augmented with an extra bit for whether to save/restore APX).
The register allocation also becomes very similar, with %edi/%rdi
pointing to the vmx (resp. svm) argument (patches 1-4).

Thanks to this, the code to restore the guest SPEC_CTRL value is the
same up to the register names and can be dropped into vmx/vmenter.S.
On the vmexit side the only change required is support for
X86_FEATURE_KERNEL_IBRS, which is a single ALTERNATIVE macro.

This also introduces vmenter.h, which hosts common code between
vmx/vmenter.S and svm/vmenter.S, and which will be augmented
further by the APX enablement series.

Paolo

v2->v3:
- add extra patch so that it actually works [Chang S. Bae]
- fix incorrect reference to KVM_ENTER_RUN_* in comments
- preserve LFENCE in the eIBRS case [sashiko]

v1->v2:
- fix "Reload @vmx to RAX" comment [Binbin]
- fix polarity of KVM_ENTER_SAVE_SPEC_CTRL in SVM, which would
  have caused problems when the macros are reused for VMX
- adjust prototypes of __svm_vcpu_run and __svm_sev_es_vcpu_run
- fix order of ALTERNATIVE arguments for X86_FEATURE_KERNEL_IBRS.
  Add comment
- Leave @flags and @vmx on the stack during RESTORE_HOST_SPEC_CTRL_BODY.
  [Uros, Binbin]



Paolo Bonzini (8):
  KVM: VMX: remove regs argument of __vmx_vcpu_run
  KVM: VMX: more cleanups to __vmx_vcpu_run
  KVM: SVM: prepare for making SPEC_CTRL switch common with VMX
  KVM: SVM: pass struct vcpu_svm to msr_write_intercepted
  KVM: SVM: adopt the same VMX_RUN_* flags as VMX
  KVM: SVM: extract RESTORE_*_SPEC_CTRL_BODY out of svm/vmenter.S
  KVM: VMX: switch to RESTORE_GUEST_SPEC_CTRL_BODY
  KVM: VMX: replace vmx_spec_ctrl_restore_host with
    RESTORE_HOST_SPEC_CTRL_BODY

 arch/x86/kvm/kvm-asm-offsets.c |   1 +
 arch/x86/kvm/svm/svm.c         |  23 +++--
 arch/x86/kvm/svm/svm.h         |   4 +-
 arch/x86/kvm/svm/vmenter.S     | 103 +++++-------------
 arch/x86/kvm/vmenter.h         |  80 ++++++++++++++
 arch/x86/kvm/vmx/run_flags.h   |   9 --
 arch/x86/kvm/vmx/vmenter.S     | 184 +++++++++++++++------------------
 arch/x86/kvm/vmx/vmx.c         |  39 ++-----
 arch/x86/kvm/vmx/vmx.h         |   7 +-
 9 files changed, 212 insertions(+), 238 deletions(-)
 create mode 100644 arch/x86/kvm/vmenter.h
 delete mode 100644 arch/x86/kvm/vmx/run_flags.h

-- 
2.52.0