KVM: SVM: Handle event vectoring error in check_emulate_instruction()

Detect unhandleable vectoring in check_emulate_instruction() to prevent
infinite retry loops on SVM, and to eliminate the main differences in how
VM-Exits during event vectoring are handled on SVM versus VMX.  E.g. if
the vCPU puts its IDT in emulated MMIO memory and generates an event,
without the check_emulate_instruction() change, SVM will re-inject the
event and resume the guest, and effectively put the vCPU into an infinite
loop.

Signed-off-by: Ivan Orlov <iorlov@amazon.com>
Link: https://lore.kernel.org/r/20241217181458.68690-6-iorlov@amazon.com


[sean: grab "svm" locally, massage changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>