Subject: [PATCH v3 24/55] KVM: arm/arm64: vgic-new: Add ENABLE registers handlers

From: [email-masked] (Marc Zyngier)
Date: Wed, 11 May 2016 15:26:30 +0100

On 11/05/16 14:39, Andre Przywara wrote:
> Hi,
> 
> On 11/05/16 14:13, Marc Zyngier wrote:
>> On 11/05/16 13:34, Christoffer Dall wrote:
>>> On Fri, May 06, 2016 at 11:45:37AM +0100, Andre Przywara wrote:
>>>> As the enable register handlers are shared between the v2 and v3
>>>> emulation, their implementation goes into vgic-mmio.c, to be easily
>>>> referenced from the v3 emulation as well later.
>>>>
>>>> Signed-off-by: Andre Przywara <[email-masked]>
>>>> ---
>>>> Changelog RFC..v1:
>>>> - use lower bits of address to determine IRQ number
>>>> - remove TODO, confirmed to be fine
>>>>
>>>> Changelog v1 .. v2:
>>>> - adapt to new MMIO framework
>>>>
>>>>  virt/kvm/arm/vgic/vgic-mmio-v2.c |  4 +--
>>>>  virt/kvm/arm/vgic/vgic-mmio.c    | 56 ++++++++++++++++++++++++++++++++++++++++
>>>>  virt/kvm/arm/vgic/vgic-mmio.h    | 11 ++++++++
>>>>  3 files changed, 69 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/virt/kvm/arm/vgic/vgic-mmio-v2.c b/virt/kvm/arm/vgic/vgic-mmio-v2.c
>>>> index 69e96f7..448d1da 100644
>>>> --- a/virt/kvm/arm/vgic/vgic-mmio-v2.c
>>>> +++ b/virt/kvm/arm/vgic/vgic-mmio-v2.c
>>>> @@ -72,9 +72,9 @@ static const struct vgic_register_region vgic_v2_dist_registers[] = {
>>>>  	REGISTER_DESC_WITH_BITS_PER_IRQ(GIC_DIST_IGROUP,
>>>>  		vgic_mmio_read_rao, vgic_mmio_write_wi, 1),
>>>>  	REGISTER_DESC_WITH_BITS_PER_IRQ(GIC_DIST_ENABLE_SET,
>>>> -		vgic_mmio_read_raz, vgic_mmio_write_wi, 1),
>>>> +		vgic_mmio_read_enable, vgic_mmio_write_senable, 1),
>>>>  	REGISTER_DESC_WITH_BITS_PER_IRQ(GIC_DIST_ENABLE_CLEAR,
>>>> -		vgic_mmio_read_raz, vgic_mmio_write_wi, 1),
>>>> +		vgic_mmio_read_enable, vgic_mmio_write_cenable, 1),
>>>>  	REGISTER_DESC_WITH_BITS_PER_IRQ(GIC_DIST_PENDING_SET,
>>>>  		vgic_mmio_read_raz, vgic_mmio_write_wi, 1),
>>>>  	REGISTER_DESC_WITH_BITS_PER_IRQ(GIC_DIST_PENDING_CLEAR,
>>>> diff --git a/virt/kvm/arm/vgic/vgic-mmio.c b/virt/kvm/arm/vgic/vgic-mmio.c
>>>> index 41cf4f4..077ae86 100644
>>>> --- a/virt/kvm/arm/vgic/vgic-mmio.c
>>>> +++ b/virt/kvm/arm/vgic/vgic-mmio.c
>>>> @@ -46,6 +46,62 @@ void vgic_mmio_write_wi(struct kvm_vcpu *vcpu, gpa_t addr,
>>>>  	/* Ignore */
>>>>  }
>>>>  
>>>> +/*
>>>> + * Read accesses to both GICD_ICENABLER and GICD_ISENABLER return the value
>>>> + * of the enabled bit, so there is only one function for both here.
>>>> + */
>>>> +unsigned long vgic_mmio_read_enable(struct kvm_vcpu *vcpu,
>>>> +				    gpa_t addr, unsigned int len)
>>>> +{
>>>> +	u32 intid = (addr & 0x7f) * 8;
>>>
>>> is there anything we can do about this to make it more intuitive?  A
>>> macro to generate the mask/offset based on bits per interrupt or
>>> something?
>>
>> Untested (and thus probably wrong):
>>
>> #define VGIC_ADDR_IRQ_MASK(bits) ((1024 - 1) >> (4 - (bits))
> 
> What about if bits is 8?

Gnii. This should be ((1024 - 1) >> (4 - ffs(bits))

> Wouldn't GENMASK(bits + 10 - 2, 0) do the trick?

I really can't see how that works... It could be
GENMASK(10 - 1 - ffs(bits), 0) though.

>> #define VGIC_ADDR_IRQ_MULT(bits) (8 / (bits))
> 
> IROUTER has a bits_per_irq value of 64. We just don't need to call it
> from there, but it would be nice if it could cover this.
> But I don't know a neat solution for this either.

Me neither, but I don't see that as a major issue so far.

	M.
-- 
Jazz is not dead. It just smells funny...