Once an exception has been injected, any side effects related to
the exception (such as setting CR2 or DR6) have been taked place.
Therefore, once KVM sets the VM-entry interruption information
field or the AMD EVENTINJ field, the next VM-entry must deliver that
exception.

Pending interrupts are processed after injected exceptions, so
in theory it would not be a problem to use KVM_INTERRUPT when
an injected exception is present.  However, DOSEMU is using
run->ready_for_interrupt_injection to detect interrupt windows
and then using KVM_SET_SREGS/KVM_SET_REGS to inject the
interrupt manually.  For this to work, the interrupt window
must be delayed after the completion of the previous event
injection.

Cc: stable@vger.kernel.org
Reported-by: Stas Sergeev <stsp2@yandex.ru>
Tested-by: Stas Sergeev <stsp2@yandex.ru>
Fixes: 71cc849b ("KVM: x86: Fix split-irqchip vs interrupt injection window request")
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>