Re: [PATCH] KVM: SVM: Fix x2APIC Logical ID calculation for avic_kick_target_vcpus_fast

[Maxim Levitsky]

On Tue, 2022-06-28 at 07:33 -0500, Suravee Suthikulpanit wrote:
> For X2APIC ID in cluster mode, the logical ID is bit [15:0].
> 
> Fixes: 603ccef42ce9 ("KVM: x86: SVM: fix avic_kick_target_vcpus_fast")
> Cc: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx>
> ---
>  arch/x86/kvm/svm/avic.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
> index a830468d9cee..29f393251c4c 100644
> --- a/arch/x86/kvm/svm/avic.c
> +++ b/arch/x86/kvm/svm/avic.c
> @@ -378,7 +378,7 @@ static int avic_kick_target_vcpus_fast(struct kvm *kvm, struct kvm_lapic *source
>  
>  		if (apic_x2apic_mode(source)) {
>  			/* 16 bit dest mask, 16 bit cluster id */
> -			bitmap = dest & 0xFFFF0000;
> +			bitmap = dest & 0xFFFF;
>  			cluster = (dest >> 16) << 4;
>  		} else if (kvm_lapic_get_reg(source, APIC_DFR) == APIC_DFR_FLAT) {
>  			/* 8 bit dest mask*/

Ouch, sorry about that :(

It just shows how much this code needs a test, I will write one really soon.


Reviewed-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>


Best regards,
	Maxim Levitsky