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KVM: nSVM: Clear EVENTINJ fields in vmcb12 on nested #VMEXIT

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According to the APM, from the reference of the VMRUN instruction:

  Upon #VMEXIT, the processor performs the following actions in order to
  return to the host execution context:

  ...

  clear EVENTINJ field in VMCB

KVM already syncs EVENTINJ fields from vmcb02 to cached vmcb12 on every
L2->L0  #VMEXIT. Since these fields are zeroed by the CPU on #VMEXIT, they
will mostly be zeroed in vmcb12 on nested #VMEXIT by nested_svm_vmexit().

However, this is not the case when:

  1. Consistency checks fail, as nested_svm_vmexit() is not called.
  2. Entering guest mode fails before L2 runs (e.g. due to failed load of
     CR3).

(2) was broken by commit 2d8a42be0e ("KVM: nSVM: synchronize VMCB
controls updated by the processor on every vmexit"), as prior to that
nested_svm_vmexit() always zeroed EVENTINJ fields.

Explicitly clear the fields in all nested #VMEXIT code paths.

Fixes: 3d6368ef58 ("KVM: SVM: Add VMRUN handler")
Fixes: 2d8a42be0e ("KVM: nSVM: synchronize VMCB controls updated by the processor on every vmexit")
Cc: stable@vger.kernel.org
Signed-off-by: Yosry Ahmed <yosry@kernel.org>
Link: https://patch.msgid.link/20260303003421.2185681-12-yosry@kernel.org
[sean: massage changelog formatting]
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Yosry Ahmed 2026-03-03 00:34:05 +00:00 committed by Sean Christopherson
parent f85a6ce06e
commit 69b721a86d
1 changed files with 4 additions and 2 deletions
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6
arch/x86/kvm/svm/nested.c
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@ -1035,6 +1035,8 @@ int nested_svm_vmrun(struct kvm_vcpu *vcpu)
vmcb12->control.exit_code = SVM_EXIT_ERR;
vmcb12->control.exit_info_1 = 0;
vmcb12->control.exit_info_2 = 0;
vmcb12->control.event_inj = 0;
vmcb12->control.event_inj_err = 0;
svm_set_gif(svm, false);
goto out;
}
@ -1178,9 +1180,9 @@ static int nested_svm_vmexit_update_vmcb12(struct kvm_vcpu *vcpu)
if (nested_vmcb12_has_lbrv(vcpu))
svm_copy_lbrs(&vmcb12->save, &vmcb02->save);
vmcb12->control.event_inj = 0;
vmcb12->control.event_inj_err = 0;
vmcb12->control.int_ctl = svm->nested.ctl.int_ctl;
vmcb12->control.event_inj = svm->nested.ctl.event_inj;
vmcb12->control.event_inj_err = svm->nested.ctl.event_inj_err;
trace_kvm_nested_vmexit_inject(vmcb12->control.exit_code,
vmcb12->control.exit_info_1,