[0/6] Introduce KVM_{GET|SET}_SREGS2 and fix PDPTR migration

Message

Maxim Levitsky April 1, 2021, 2:18 p.m. UTC

This patch set aims to fix few flaws that were discovered
in KVM_{GET|SET}_SREGS on x86:

* There is no support for reading/writing PDPTRs although
  these are considered to be part of the guest state.

* There is useless interrupt bitmap which isn't needed

* No support for future extensions (via flags and such)

Final two patches in this patch series allow to
correctly migrate PDPTRs when new API is used.

This patch series was tested by doing nested migration test
of 32 bit PAE L1 + 32 bit PAE L2 on AMD and Intel and by
nested migration test of 64 bit L1 + 32 bit PAE L2 on AMD.
The later test currently fails on Intel (regardless of my patches).

Finally patch 2 in this patch series fixes a rare L0 kernel oops,
which I can trigger by migrating a hyper-v machine.

Best regards,
	Maxim Levitskky

Maxim Levitsky (6):
  KVM: nVMX: delay loading of PDPTRs to KVM_REQ_GET_NESTED_STATE_PAGES
  KVM: nSVM: call nested_svm_load_cr3 on nested state load
  KVM: x86: introduce kvm_register_clear_available
  KVM: x86: Introduce KVM_GET_SREGS2 / KVM_SET_SREGS2
  KVM: nSVM: avoid loading PDPTRs after migration when possible
  KVM: nVMX: avoid loading PDPTRs after migration when possible

 Documentation/virt/kvm/api.rst  |  43 ++++++++++
 arch/x86/include/asm/kvm_host.h |   7 ++
 arch/x86/include/uapi/asm/kvm.h |  13 +++
 arch/x86/kvm/kvm_cache_regs.h   |  12 +++
 arch/x86/kvm/svm/nested.c       |  55 ++++++++-----
 arch/x86/kvm/svm/svm.c          |   6 +-
 arch/x86/kvm/vmx/nested.c       |  26 ++++--
 arch/x86/kvm/x86.c              | 136 ++++++++++++++++++++++++++------
 include/uapi/linux/kvm.h        |   5 ++
 9 files changed, 249 insertions(+), 54 deletions(-)