From: Sean Christopherson seanjc@google.com
commit ba5838abb05334e4abfdff1490585c7f365e0424 upstream.
Inject a #GP if the guest attempts to set reserved bits in the x2APIC-only Self-IPI register. Bits 7:0 hold the vector, all other bits are reserved.
Reported-by: Marc Orr marcorr@google.com Cc: Ben Gardon bgardon@google.com Cc: Venkatesh Srinivas venkateshs@chromium.org Cc: stable@vger.kernel.org Reviewed-by: Maxim Levitsky mlevitsk@redhat.com Link: https://lore.kernel.org/r/20230107011025.565472-2-seanjc@google.com Signed-off-by: Sean Christopherson seanjc@google.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/kvm/lapic.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)
--- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -2127,10 +2127,14 @@ int kvm_lapic_reg_write(struct kvm_lapic break;
case APIC_SELF_IPI: - if (apic_x2apic_mode(apic)) - kvm_apic_send_ipi(apic, APIC_DEST_SELF | (val & APIC_VECTOR_MASK), 0); - else + /* + * Self-IPI exists only when x2APIC is enabled. Bits 7:0 hold + * the vector, everything else is reserved. + */ + if (!apic_x2apic_mode(apic) || (val & ~APIC_VECTOR_MASK)) ret = 1; + else + kvm_apic_send_ipi(apic, APIC_DEST_SELF | val, 0); break; default: ret = 1;