Subject: [PATCH v3 23/55] KVM: arm/arm64: vgic-new: Add CTLR, TYPER and IIDR handlers

From: [email-masked] (Marc Zyngier)
Date: Wed, 11 May 2016 14:27:53 +0100

On 11/05/16 14:15, Christoffer Dall wrote:
> On Wed, May 11, 2016 at 01:51:36PM +0100, Marc Zyngier wrote:
>> On 11/05/16 13:05, Christoffer Dall wrote:
>>> On Fri, May 06, 2016 at 11:45:36AM +0100, Andre Przywara wrote:
>>>> From: Marc Zyngier <[email-masked]>
>>>>
>>>> Those three registers are v2 emulation specific, so their implementation
>>>> lives entirely in vgic-mmio-v2.c. Also they are handled in one function,
>>>> as their implementation is pretty simple.
>>>> When the guest enables the distributor, we kick all VCPUs to get
>>>> potentially pending interrupts serviced.
>>>>
>>>> Signed-off-by: Marc Zyngier <[email-masked]>
>>>> Signed-off-by: Andre Przywara <[email-masked]>
>>>> ---
>>>> Changelog RFC..v1:
>>>> - kick VCPUs is the distributor gets enabled
>>>> - improve comment
>>>>
>>>> Changelog v1 .. v2:
>>>> - adapt to new MMIO framework
>>>> - use switch() statements to improve readability
>>>>
>>>> Changelog v2 .. v3:
>>>> - add vgic_kick_vcpus() implementation
>>>>
>>>>  include/linux/irqchip/arm-gic.h  |  1 +
>>>>  virt/kvm/arm/vgic/vgic-mmio-v2.c | 48 +++++++++++++++++++++++++++++++++++++++-
>>>>  virt/kvm/arm/vgic/vgic.c         | 15 +++++++++++++
>>>>  virt/kvm/arm/vgic/vgic.h         |  4 ++++
>>>>  4 files changed, 67 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/include/linux/irqchip/arm-gic.h b/include/linux/irqchip/arm-gic.h
>>>> index be0d26f..fd05185 100644
>>>> --- a/include/linux/irqchip/arm-gic.h
>>>> +++ b/include/linux/irqchip/arm-gic.h
>>>> @@ -33,6 +33,7 @@
>>>>  
>>>>  #define GIC_DIST_CTRL			0x000
>>>>  #define GIC_DIST_CTR			0x004
>>>> +#define GIC_DIST_IIDR			0x008
>>>>  #define GIC_DIST_IGROUP			0x080
>>>>  #define GIC_DIST_ENABLE_SET		0x100
>>>>  #define GIC_DIST_ENABLE_CLEAR		0x180
>>>> diff --git a/virt/kvm/arm/vgic/vgic-mmio-v2.c b/virt/kvm/arm/vgic/vgic-mmio-v2.c
>>>> index 2729a22..69e96f7 100644
>>>> --- a/virt/kvm/arm/vgic/vgic-mmio-v2.c
>>>> +++ b/virt/kvm/arm/vgic/vgic-mmio-v2.c
>>>> @@ -20,9 +20,55 @@
>>>>  #include "vgic.h"
>>>>  #include "vgic-mmio.h"
>>>>  
>>>> +static unsigned long vgic_mmio_read_v2_misc(struct kvm_vcpu *vcpu,
>>>> +					    gpa_t addr, unsigned int len)
>>>> +{
>>>> +	u32 value;
>>>> +
>>>> +	switch (addr & 0x0c) {
>>>> +	case GIC_DIST_CTRL:
>>>> +		value = vcpu->kvm->arch.vgic.enabled ? GICD_ENABLE : 0;
>>>> +		break;
>>>> +	case GIC_DIST_CTR:
>>>> +		value = vcpu->kvm->arch.vgic.nr_spis + VGIC_NR_PRIVATE_IRQS;
>>>> +		value = (value >> 5) - 1;
>>>> +		value |= (atomic_read(&vcpu->kvm->online_vcpus) - 1) << 5;
>>>> +		break;
>>>> +	case GIC_DIST_IIDR:
>>>> +		value = (PRODUCT_ID_KVM << 24) | (IMPLEMENTER_ARM << 0);
>>>> +		break;
>>>> +	default:
>>>> +		return 0;
>>>> +	}
>>>> +
>>>> +	return extract_bytes(value, addr & 3, len);
>>>> +}
>>>> +
>>>> +static void vgic_mmio_write_v2_misc(struct kvm_vcpu *vcpu,
>>>> +				    gpa_t addr, unsigned int len,
>>>> +				    unsigned long val)
>>>> +{
>>>> +	switch (addr & 0x0c) {
>>>> +	case GIC_DIST_CTRL:
>>>> +		if (!(addr & 1)) {
>>>
>>> what is this !(addr & 1) check?
>>
>> We check that the write includes the lowest byte of the register. But as
>> we only have aligned accesses, it probably doesn't matter... I'll hack
>> that away.
>>
> where do we check to only have aligned accesses?

Looks like a missing feature. The v2 spec says:

4.1.4 GIC register access
All registers support 32-bit word accesses with the access type defined
in Table 4-1 on page 4-73 and Table 4-2 on page 4-74.
In addition, the GICD_IPRIORITYRn, GICD_ITARGETSRn, GICD_CPENDSGIRn, and
GICD_SPENDSGIRn registers support byte accesses.

Similar thing for v3 (8.1.3).

By the look of it, we should add checks in all accessors. I'll get onto it.

Thanks,

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