[PATCH v3 47/55] KVM: arm/arm64: vgic-new: Add userland GIC CPU interface access

[christoffer.dall@linaro.org (Christoffer Dall)]

On Thu, May 12, 2016 at 07:52:38PM +0100, Andre Przywara wrote:
> Hi,
> 
> On 12/05/16 19:47, Christoffer Dall wrote:
> > On Fri, May 06, 2016 at 11:46:00AM +0100, Andre Przywara wrote:
> >> Using the VMCR accessors we provide access to GIC CPU interface state
> >> to userland by wiring it up to the existing userland interface.
> >> [Marc: move and make VMCR accessors static, streamline MMIO handlers]
> > 
> > does this mean Marc did this and serves as credit or is it a lost
> > reminder?
> 
> It was meant as credit. I thought that is the usual annotation for this?
> 

I'm not sure if that's the usual way, I read it as a reminder, but it's
not too important.  Mostly wanting to make sure we're not forgetting
some todo item.

> >>
> >> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> >> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
> >> ---
> >> Changelog v2 .. v3:
> >> - total rework, moving into vgic-mmio-v2.c
> >> - move vmcr accessor wrapper functions into this file
> >> - use the register description table for CPU i/f registers as well
> >> - add RAZ/WI handling for the active priority registers
> >> - streamline MMIO handler functions
> >>
> >>  virt/kvm/arm/vgic/vgic-kvm-device.c |   2 +-
> >>  virt/kvm/arm/vgic/vgic-mmio-v2.c    | 104 ++++++++++++++++++++++++++++++++++++
> >>  virt/kvm/arm/vgic/vgic.h            |   2 +
> >>  3 files changed, 107 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/virt/kvm/arm/vgic/vgic-kvm-device.c b/virt/kvm/arm/vgic/vgic-kvm-device.c
> >> index bb33af8..2122ff2 100644
> >> --- a/virt/kvm/arm/vgic/vgic-kvm-device.c
> >> +++ b/virt/kvm/arm/vgic/vgic-kvm-device.c
> >> @@ -300,7 +300,7 @@ static int vgic_attr_regs_access(struct kvm_device *dev,
> >>  
> >>  	switch (attr->group) {
> >>  	case KVM_DEV_ARM_VGIC_GRP_CPU_REGS:
> >> -		ret = -EINVAL;
> >> +		ret = vgic_v2_cpuif_uaccess(vcpu, is_write, addr, reg);
> >>  		break;
> >>  	case KVM_DEV_ARM_VGIC_GRP_DIST_REGS:
> >>  		ret = vgic_v2_dist_uaccess(vcpu, is_write, addr, reg);
> >> diff --git a/virt/kvm/arm/vgic/vgic-mmio-v2.c b/virt/kvm/arm/vgic/vgic-mmio-v2.c
> >> index c453e6f..0060539 100644
> >> --- a/virt/kvm/arm/vgic/vgic-mmio-v2.c
> >> +++ b/virt/kvm/arm/vgic/vgic-mmio-v2.c
> >> @@ -206,6 +206,84 @@ static void vgic_mmio_write_sgipends(struct kvm_vcpu *vcpu,
> >>  	}
> >>  }
> >>  
> >> +static void vgic_set_vmcr(struct kvm_vcpu *vcpu, struct vgic_vmcr *vmcr)
> >> +{
> >> +	if (kvm_vgic_global_state.type == VGIC_V2)
> >> +		vgic_v2_set_vmcr(vcpu, vmcr);
> >> +	else
> >> +		vgic_v3_set_vmcr(vcpu, vmcr);
> >> +}
> >> +
> >> +static void vgic_get_vmcr(struct kvm_vcpu *vcpu, struct vgic_vmcr *vmcr)
> >> +{
> >> +	if (kvm_vgic_global_state.type == VGIC_V2)
> >> +		vgic_v2_get_vmcr(vcpu, vmcr);
> >> +	else
> >> +		vgic_v3_get_vmcr(vcpu, vmcr);
> >> +}
> >> +
> >> +#define GICC_ARCH_VERSION_V2	0x2
> >> +
> >> +/* These are for userland accesses only, there is no guest-facing emulation. */
> >> +static unsigned long vgic_mmio_read_vcpuif(struct kvm_vcpu *vcpu,
> >> +					   gpa_t addr, unsigned int len)
> >> +{
> >> +	struct vgic_vmcr vmcr;
> >> +	u32 val;
> >> +
> >> +	vgic_get_vmcr(vcpu, &vmcr);
> >> +
> >> +	switch (addr & 0xff) {
> >> +	case GIC_CPU_CTRL:
> >> +		val = vmcr.ctlr;
> >> +		break;
> >> +	case GIC_CPU_PRIMASK:
> >> +		val = vmcr.pmr;
> >> +		break;
> >> +	case GIC_CPU_BINPOINT:
> >> +		val = vmcr.bpr;
> >> +		break;
> >> +	case GIC_CPU_ALIAS_BINPOINT:
> >> +		val = vmcr.abpr;
> >> +		break;
> >> +	case GIC_CPU_IDENT:
> >> +		val = ((PRODUCT_ID_KVM << 20) |
> >> +		       (GICC_ARCH_VERSION_V2 << 16) |
> >> +		       IMPLEMENTER_ARM);
> >> +		break;
> >> +	default:
> >> +		return 0;
> >> +	}
> >> +
> >> +	return extract_bytes(val, addr & 3, len);
> > 
> > I don't think we allow anything than a full 32-bit aligned accesses
> > from userspace - we shouldn't at least.
> 
> Indeed - I think userland was always 32-bit only. And since last night
> we even enforce this. So potentially there are more extract_bytes()
> calls that can go.
> 
Right.

-Christoffer