KVM: nVMX: Immediately refresh APICv controls as needed on nested VM-Exit

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commit 2976313883 upstream.

If an APICv status updated was pended while L2 was active, immediately
refresh vmcs01's controls instead of pending KVM_REQ_APICV_UPDATE as
kvm_vcpu_update_apicv() only calls into vendor code if a change is
necessary.

E.g. if APICv is inhibited, and then activated while L2 is running:

  kvm_vcpu_update_apicv()
  |
  -> __kvm_vcpu_update_apicv()
     |
     -> apic->apicv_active = true
      |
      -> vmx_refresh_apicv_exec_ctrl()
         |
         -> vmx->nested.update_vmcs01_apicv_status = true
          |
          -> return

Then L2 exits to L1:

  __nested_vmx_vmexit()
  |
  -> kvm_make_request(KVM_REQ_APICV_UPDATE)

  vcpu_enter_guest(): KVM_REQ_APICV_UPDATE
  -> kvm_vcpu_update_apicv()
     |
     -> __kvm_vcpu_update_apicv()
        |
        -> return // because if (apic->apicv_active == activate)

Reported-by: Chao Gao <chao.gao@intel.com>
Closes: https://lore.kernel.org/all/aQ2jmnN8wUYVEawF@intel.com
Fixes: 7c69661e22 ("KVM: nVMX: Defer APICv updates while L2 is active until L1 is active")
Cc: stable@vger.kernel.org
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
[sean: write changelog]
Link: https://patch.msgid.link/20251205231913.441872-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

...

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Dongli Zhang 2025-12-05 15:19:05 -08:00 • committed by Greg Kroah-Hartman

parent 4dac2f321e

commit 3eaa520d28

1 changed files with 2 additions and 1 deletions

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arch/x86/kvm/vmx/nested.c

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