Re: [PATCH] [RFC] KVM: arm64/vgic: Populate GICR_TYPER with Aff3

[Oliver Upton]

Hi Saurav,

On Mon, Feb 05, 2024 at 06:43:26PM +0000, Saurav Sachidanand wrote:

[...]

> diff --git a/arch/arm64/kvm/vgic/vgic-mmio-v3.c b/arch/arm64/kvm/vgic/vgic-mmio-v3.c
> index c15ee1df036a..26bc838ce14c 100644
> --- a/arch/arm64/kvm/vgic/vgic-mmio-v3.c
> +++ b/arch/arm64/kvm/vgic/vgic-mmio-v3.c
> @@ -324,6 +324,7 @@ static unsigned long vgic_mmio_read_v3r_typer(struct kvm_vcpu *vcpu,
>  	u64 value;
>  
>  	value = (u64)(mpidr & GENMASK(23, 0)) << 32;
> +	value |= (u64)((mpidr >> 32) & GENMASK(7, 0)) << 56;

This looks suspiciously similar to what MPIDR_AFFINITY_LEVEL()
accomplishes. I think we can tolerate a few extra lines of code to make
the entire thing more self-documenting, like:

	value = ((u64)MPIDR_AFFINITY_LEVEL(mpidr, 3) << 56 |
		MPIDR_AFFINITY_LEVEL(mpidr, 2) << 48 |
		MPIDR_AFFINITY_LEVEL(mpidr, 1) << 40 |
		MPIDR_AFFINITY_LEVEL(mpidr, 0) << 32);

-- 
Thanks,
Oliver