From 14f36160c7d1446e8e9555609023d08a55c222df Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Sat, 7 Jan 2023 01:10:20 +0000 Subject: [PATCH] KVM: x86: Inject #GP if WRMSR sets reserved bits in APIC Self-IPI 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 Cc: Ben Gardon Cc: Venkatesh Srinivas Cc: stable@vger.kernel.org Reviewed-by: Maxim Levitsky Link: https://lore.kernel.org/r/20230107011025.565472-2-seanjc@google.com Signed-off-by: Sean Christopherson Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/lapic.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index 6cfe8a9..9fcfd86 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -2227,10 +2227,14 @@ static int kvm_lapic_reg_write(struct kvm_lapic *apic, u32 reg, u32 val) 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; -- 2.7.4