KVM: x86: emulate wait-for-SIPI and SIPI-VMExit
Background: We have a lightweight HV, it needs INIT-VMExit and SIPI-VMExit to wake-up APs for guests since it do not monitor the Local APIC. But currently virtual wait-for-SIPI(WFS) state is not supported in nVMX, so when running on top of KVM, the L1 HV cannot receive the INIT-VMExit and SIPI-VMExit which cause the L2 guest cannot wake up the APs. According to Intel SDM Chapter 25.2 Other Causes of VM Exits, SIPIs cause VM exits when a logical processor is in wait-for-SIPI state. In this patch: 1. introduce SIPI exit reason, 2. introduce wait-for-SIPI state for nVMX, 3. advertise wait-for-SIPI support to guest. When L1 hypervisor is not monitoring Local APIC, L0 need to emulate INIT-VMExit and SIPI-VMExit to L1 to emulate INIT-SIPI-SIPI for L2. L2 LAPIC write would be traped by L0 Hypervisor(KVM), L0 should emulate the INIT/SIPI vmexit to L1 hypervisor to set proper state for L2's vcpu state. Handle procdure: Source vCPU: L2 write LAPIC.ICR(INIT). L0 trap LAPIC.ICR write(INIT): inject a latched INIT event to target vCPU. Target vCPU: L0 emulate an INIT VMExit to L1 if is guest mode. L1 set guest VMCS, guest_activity_state=WAIT_SIPI, vmresume. L0 set vcpu.mp_state to INIT_RECEIVED if (vmcs12.guest_activity_state == WAIT_SIPI). Source vCPU: L2 write LAPIC.ICR(SIPI). L0 trap LAPIC.ICR write(INIT): inject a latched SIPI event to traget vCPU. Target vCPU: L0 emulate an SIPI VMExit to L1 if (vcpu.mp_state == INIT_RECEIVED). L1 set CS:IP, guest_activity_state=ACTIVE, vmresume. L0 resume to L2. L2 start-up. Signed-off-by:Yadong Qi <yadong.qi@intel.com> Message-Id: <20200922052343.84388-1-yadong.qi@intel.com> Signed-off-by:
Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20201106065122.403183-1-yadong.qi@intel.com> Signed-off-by:
Paolo Bonzini <pbonzini@redhat.com>
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