[PATCH 0/6] KVM: nSVM: Fix issues when SMM is entered from L2

[Vitaly Kuznetsov <vkuznets@redhat.com>]

This is a continuation of "[PATCH RFC] KVM: nSVM: Fix L1 state corruption
upon return from SMM". 

VMCB split commit 4995a3685f1b ("KVM: SVM: Use a separate vmcb for the
nested L2 guest") broke return from SMM when we entered there from guest
(L2) mode. Gen2 WS2016/Hyper-V is known to do this on boot. The problem
appears to be that VMCB01 gets irreversibly destroyed during SMM execution.
Previously, we used to have 'hsave' VMCB where regular (pre-SMM) L1's state
was saved upon nested_svm_vmexit() but now we just switch to VMCB01 from
VMCB02.

While writing a selftest for the issue, I've noticed that 'svm->nested.ctl'
doesn't get restored after KVM_GET_NESTED_STATE/KVM_SET_NESTED_STATE cycle
when guest happens to be in SMM triggered from L2. "KVM: nSVM: Restore
nested control upon leaving SMM" is aimed to fix that.

First two patches of the series add missing sanity checks for 
MSR_VM_HSAVE_PA which has to be page aligned and not zero.

Vitaly Kuznetsov (6):
  KVM: nSVM: Check the value written to MSR_VM_HSAVE_PA
  KVM: nSVM: Check that VM_HSAVE_PA MSR was set before VMRUN
  KVM: nSVM: Introduce svm_copy_nonvmloadsave_state()
  KVM: nSVM: Fix L1 state corruption upon return from SMM
  KVM: nSVM: Restore nested control upon leaving SMM
  KVM: selftests: smm_test: Test SMM enter from L2

 arch/x86/kvm/svm/nested.c                     | 45 +++++++-----
 arch/x86/kvm/svm/svm.c                        | 51 +++++++++++++-
 arch/x86/kvm/svm/svm.h                        |  4 ++
 tools/testing/selftests/kvm/x86_64/smm_test.c | 70 +++++++++++++++++--
 4 files changed, 144 insertions(+), 26 deletions(-)

-- 
2.31.1