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  1. 08 Jan, 2021 35 commits
  3. 07 Jan, 2021 5 commits
    • Tom Lendacky's avatar
      KVM: SVM: Add support for booting APs in an SEV-ES guest · 647daca2
      Tom Lendacky authored 
      Typically under KVM, an AP is booted using the INIT-SIPI-SIPI sequence,
where the guest vCPU register state is updated and then the vCPU is VMRUN
to begin execution of the AP. For an SEV-ES guest, this won't work because
the guest register state is encrypted.

Following the GHCB specification, the hypervisor must not alter the guest
register state, so KVM must track an AP/vCPU boot. Should the guest want
to park the AP, it must use the AP Reset Hold exit event in place of, for
example, a HLT loop.

First AP boot (first INIT-SIPI-SIPI sequence):
  Execute the AP (vCPU) as it was initialized and measured by the SEV-ES
  support. It is up to the guest to transfer control of the AP to the
  proper location.

Subsequent AP boot:
  KVM will expect to receive an AP Reset Hold exit event indicating that
  the vCPU is being parked and will require an INIT-SIPI-SIPI sequence to
  awaken it. When the AP Reset Hold exit event is received, KVM will place
  the vCPU into a simulated HLT mode. Upon receiving the INIT-SIPI-SIPI
  sequence, KVM will make the vCPU runnable. It is again up to the guest
  to then transfer control of the AP to the proper location.

  To differentiate between an actual HLT and an AP Reset Hold, a new MP
  state is introduced, KVM_MP_STATE_AP_RESET_HOLD, which the vCPU is
  placed in upon receiving the AP Reset Hold exit event. Additionally, to
  communicate the AP Reset Hold exit event up to userspace (if needed), a
  new exit reason is introduced, KVM_EXIT_AP_RESET_HOLD.

A new x86 ops function is introduced, vcpu_deliver_sipi_vector, in order
to accomplish AP booting. For VMX, vcpu_deliver_sipi_vector is set to the
original SIPI delivery function, kvm_vcpu_deliver_sipi_vector(). SVM adds
a new function that, for non SEV-ES guests, invokes the original SIPI
delivery function, kvm_vcpu_deliver_sipi_vector(), but for SEV-ES guests,
implements the logic above.
Signed-off-by: default avatarTom Lendacky <thomas.lendacky@amd.com>
Message-Id: <e8fbebe8eb161ceaabdad7c01a5859a78b424d5e.1609791600.git.thomas.lendacky@amd.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      647daca2
    • Maxim Levitsky's avatar
      KVM: nSVM: cancel KVM_REQ_GET_NESTED_STATE_PAGES on nested vmexit · f2c7ef3b
      Maxim Levitsky authored 
      It is possible to exit the nested guest mode, entered by
svm_set_nested_state prior to first vm entry to it (e.g due to pending event)
if the nested run was not pending during the migration.

In this case we must not switch to the nested msr permission bitmap.
Also add a warning to catch similar cases in the future.

Fixes: a7d5c7ce ("KVM: nSVM: delay MSR permission processing to first nested VM run")
Signed-off-by: default avatarMaxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210107093854.882483-2-mlevitsk@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      f2c7ef3b
    • Maxim Levitsky's avatar
      KVM: nSVM: mark vmcb as dirty when forcingly leaving the guest mode · 56fe28de
      Maxim Levitsky authored 
      We overwrite most of vmcb fields while doing so, so we must
mark it as dirty.
Signed-off-by: default avatarMaxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210107093854.882483-5-mlevitsk@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      56fe28de
    • Maxim Levitsky's avatar
      KVM: nSVM: correctly restore nested_run_pending on migration · 81f76ada
      Maxim Levitsky authored 
      The code to store it on the migration exists, but no code was restoring it.

One of the side effects of fixing this is that L1->L2 injected events
are no longer lost when migration happens with nested run pending.
Signed-off-by: default avatarMaxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210107093854.882483-3-mlevitsk@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      81f76ada
    • Ben Gardon's avatar
      KVM: x86/mmu: Clarify TDP MMU page list invariants · c0dba6e4
      Ben Gardon authored 
      The tdp_mmu_roots and tdp_mmu_pages in struct kvm_arch should only contain
pages with tdp_mmu_page set to true. tdp_mmu_pages should not contain any
pages with a non-zero root_count and tdp_mmu_roots should only contain
pages with a positive root_count, unless a thread holds the MMU lock and
is in the process of modifying the list. Various functions expect these
invariants to be maintained, but they are not explictily documented. Add
to the comments on both fields to document the above invariants.
Signed-off-by: default avatarBen Gardon <bgardon@google.com>
Message-Id: <20210107001935.3732070-2-bgardon@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      c0dba6e4
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