Subject: [PATCH v3 35/55] KVM: arm/arm64: vgic-new: Add GICv3 IDREGS register handler

From: [email-masked] (Christoffer Dall)
Date: Thu, 12 May 2016 14:12:26 +0200

On Fri, May 06, 2016 at 11:45:48AM +0100, Andre Przywara wrote:
> We implement the only one ID register that is required by the
> architecture, also this is the one that Linux actually checks.
> 
> Signed-off-by: Andre Przywara <[email-masked]>
> ---
> Changelog v1 .. v2:
> - adapt to new MMIO framework
> 
>  virt/kvm/arm/vgic/vgic-mmio-v3.c | 20 ++++++++++++++++++--
>  1 file changed, 18 insertions(+), 2 deletions(-)
> 
> diff --git a/virt/kvm/arm/vgic/vgic-mmio-v3.c b/virt/kvm/arm/vgic/vgic-mmio-v3.c
> index d137242..48fba9c 100644
> --- a/virt/kvm/arm/vgic/vgic-mmio-v3.c
> +++ b/virt/kvm/arm/vgic/vgic-mmio-v3.c
> @@ -110,6 +110,22 @@ static unsigned long vgic_mmio_read_v3r_iidr(struct kvm_vcpu *vcpu,
>  	return extract_bytes(value, addr & 3, len);
>  }
>  
> +static unsigned long vgic_mmio_read_v3_idregs(struct kvm_vcpu *vcpu,
> +					      gpa_t addr, unsigned int len)
> +{
> +	u32 regnr = (addr & 0x3f) - (GICD_IDREGS & 0x3f);

this regnr thing is confusing, because it's not an index, it's an
address offset.

why can't you do:

	switch (addr & 0xffff) {
	case GICD_PIDR2:
	}

> +	u32 reg = 0;
> +
> +	switch (regnr + GICD_IDREGS) {
> +	case GICD_PIDR2:
> +		/* report a GICv3 compliant implementation */
> +		reg = 0x3b;
> +		break;
> +	}
> +
> +	return extract_bytes(reg, addr & 3, len);
> +}
> +
>  /*
>   * The GICv3 per-IRQ registers are split to control PPIs and SGIs in the
>   * redistributors, while SPIs are covered by registers in the distributor
> @@ -160,7 +176,7 @@ static const struct vgic_register_region vgic_v3_dist_registers[] = {
>  	REGISTER_DESC_WITH_BITS_PER_IRQ_SHARED(GICD_IROUTER,
>  		vgic_mmio_read_raz, vgic_mmio_write_wi, 64),
>  	REGISTER_DESC_WITH_LENGTH(GICD_IDREGS,
> -		vgic_mmio_read_raz, vgic_mmio_write_wi, 48),
> +		vgic_mmio_read_v3_idregs, vgic_mmio_write_wi, 48),
>  };
>  
>  static const struct vgic_register_region vgic_v3_rdbase_registers[] = {
> @@ -175,7 +191,7 @@ static const struct vgic_register_region vgic_v3_rdbase_registers[] = {
>  	REGISTER_DESC_WITH_LENGTH(GICR_PENDBASER,
>  		vgic_mmio_read_raz, vgic_mmio_write_wi, 8),
>  	REGISTER_DESC_WITH_LENGTH(GICR_IDREGS,
> -		vgic_mmio_read_raz, vgic_mmio_write_wi, 48),
> +		vgic_mmio_read_v3_idregs, vgic_mmio_write_wi, 48),
>  };
>  
>  static const struct vgic_register_region vgic_v3_sgibase_registers[] = {
> -- 
> 2.7.3
> 
> --
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