Re: [PATCH v2] KVM: x86: Fix reserved x2apic registers

[Paolo Bonzini <pbonzini@redhat.com>]

On 26/11/2014 16:56, Nadav Amit wrote:
> x2APIC has no registers for DFR and ICR2 (see Intel SDM 10.12.1.2 "x2APIC
> Register Address Space"). KVM needs to cause #GP on such accesses.
> 
> Fix it (DFR and ICR2 on read, ICR2 on write, DFR already handled on writes).
> 
> Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
> 
> ---
> v1->v2: Cause #GP on ICR2 write access (as Radim pointed)
> ---
>  arch/x86/kvm/lapic.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> index e0e5642..9c90d31 100644
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -1883,6 +1883,9 @@ int kvm_x2apic_msr_write(struct kvm_vcpu *vcpu, u32 msr, u64 data)
>  	if (!irqchip_in_kernel(vcpu->kvm) || !apic_x2apic_mode(apic))
>  		return 1;
>  
> +	if (reg == APIC_ICR2)
> +		return 1;
> +
>  	/* if this is ICR write vector before command */
>  	if (msr == 0x830)
>  		apic_reg_write(apic, APIC_ICR2, (u32)(data >> 32));
> @@ -1897,6 +1900,12 @@ int kvm_x2apic_msr_read(struct kvm_vcpu *vcpu, u32 msr, u64 *data)
>  	if (!irqchip_in_kernel(vcpu->kvm) || !apic_x2apic_mode(apic))
>  		return 1;
>  
> +	if (reg == APIC_DFR || reg == APIC_ICR2) {
> +		apic_debug("KVM_APIC_READ: read x2apic reserved register %x\n",
> +			   reg);
> +		return 1;
> +	}
> +
>  	if (apic_reg_read(apic, reg, 4, &low))
>  		return 1;
>  	if (msr == 0x830)
> 

Applied, thanks.

Paolo