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

[Christoffer Dall]

On Wed, May 11, 2016 at 02:27:53PM +0100, Marc Zyngier wrote:
> 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 <marc.zyngier at arm.com>
> >>>>
> >>>> 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 <marc.zyngier at arm.com>
> >>>> Signed-off-by: Andre Przywara <andre.przywara at arm.com>
> >>>> ---
> >>>> 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.
> 
Yeah, that's probably the easiest.

-Christoffer