Consider the case L1 had a pending event until it executed VMLAUNCH/VMRESUME which wasn't delivered because it was disallowed (e.g. interrupts disabled). When L1 executes VMLAUNCH/VMRESUME, L0 needs to evaluate if this pending event should cause an exit from L2 to L1 or delivered directly to L2 (In case L1 don't intercept EXTERNAL_INTERRUPT). Usually this would be handled by L0 requesting a window (e.g. IRQ window) by setting VMCS accordingly. However, this setting was done on VMCS01 and now VMCS02 is active instead. Thus, when L1 executes VMLAUNCH/VMRESUME we force L0 to perform pending event evaluation by requesting a KVM_REQ_EVENT. Note that above scenario exists when L1 KVM is about to enter L2 but requests an "immediate-exit". As in this case, L1 will disable-interrupts and then send a self-IPI before entering L2. Signed-off-by: Liran Alon <liran.alon@xxxxxxxxxx> --- arch/x86/kvm/vmx.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 1d26f3c4985b..e4eeff1f4c58 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -12575,6 +12575,22 @@ static int enter_vmx_non_root_mode(struct kvm_vcpu *vcpu, u32 *exit_qual) } /* + * If L1 had a pending event until it executed + * VMLAUNCH/VMRESUME which wasn't delivered because it was + * disallowed (e.g. interrupts disabled), L0 needs to + * evaluate if this pending event should cause an exit from L2 + * to L1 or delivered directly to L2 (In case L1 don't + * intercept EXTERNAL_INTERRUPT). + * + * Usually this would be handled by L0 requesting a window + * (e.g. IRQ window) by setting VMCS accordingly. However, + * this setting was done on VMCS01 and now VMCS02 is active + * instead. Thus, we force L0 to perform pending event + * evaluation by requesting a KVM_REQ_EVENT. + */ + kvm_make_request(KVM_REQ_EVENT, vcpu); + + /* * Note no nested_vmx_succeed or nested_vmx_fail here. At this point * we are no longer running L1, and VMLAUNCH/VMRESUME has not yet * returned as far as L1 is concerned. It will only return (and set -- 1.9.1
