KVM: TDX: Wait lapic expire when timer IRQ was injected

Call kvm_wait_lapic_expire() when POSTED_INTR_ON is set and the vector
for LVTT is set in PIR before TD entry.

KVM always assumes a timer IRQ was injected if APIC state is protected.
For TDX guest, APIC state is protected and KVM injects timer IRQ via posted
interrupt.  To avoid unnecessary wait calls, only call
kvm_wait_lapic_expire() when a timer IRQ was injected, i.e., POSTED_INTR_ON
is set and the vector for LVTT is set in PIR.

Add a helper to test PIR.

Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
Co-developed-by: Binbin Wu <binbin.wu@linux.intel.com>
Signed-off-by: Binbin Wu <binbin.wu@linux.intel.com>
Message-ID: <20250222014757.897978-7-binbin.wu@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>