From: Sean Christopherson <seanjc@xxxxxxxxxx> commit ab52be1b310bcb39e6745d34a8f0e8475d67381a upstream. Reject attempts to set bits 63:32 for 32-bit x2APIC registers, i.e. all x2APIC registers except ICR. Per Intel's SDM: Non-zero writes (by WRMSR instruction) to reserved bits to these registers will raise a general protection fault exception Opportunistically fix a typo in a nearby comment. Reported-by: Marc Orr <marcorr@xxxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Reviewed-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx> Link: https://lore.kernel.org/r/20230107011025.565472-3-seanjc@xxxxxxxxxx Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/x86/kvm/lapic.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -2949,13 +2949,17 @@ static int kvm_lapic_msr_read(struct kvm static int kvm_lapic_msr_write(struct kvm_lapic *apic, u32 reg, u64 data) { /* - * ICR is a 64-bit register in x2APIC mode (and Hyper'v PV vAPIC) and + * ICR is a 64-bit register in x2APIC mode (and Hyper-V PV vAPIC) and * can be written as such, all other registers remain accessible only * through 32-bit reads/writes. */ if (reg == APIC_ICR) return kvm_x2apic_icr_write(apic, data); + /* Bits 63:32 are reserved in all other registers. */ + if (data >> 32) + return 1; + return kvm_lapic_reg_write(apic, reg, (u32)data); }
