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

From: [email-masked] (Christoffer Dall)
Date: Fri, 13 May 2016 14:32:29 +0200

On Fri, May 13, 2016 at 01:23:02PM +0100, Andre Przywara wrote:
> Hi,
> 
> On 13/05/16 12:54, Christoffer Dall wrote:
> > On Fri, May 13, 2016 at 11:44:38AM +0100, Andre Przywara wrote:
> >> Hi,
> >>
> >> On 13/05/16 08:53, Christoffer Dall wrote:
> >>> 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 <[email-masked]>
> >>>>>> Signed-off-by: Marc Zyngier <[email-masked]>
> >>>>>> ---
> >>>>>> 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.
> >>
> >> So can I replace every call to extract_bytes() with just a "return val;"
> >> for every register that allows 32-bit accesses only?
> >> I think that's safe now, just checking ...
> > 
> > yes, I think the way we do it now, you simply return val (asuming you
> > build that variable at the right offset, even for byte accesses).
> 
> ??? If we only have word accesses, then we don't need to care about byte
> accesses? Or do I got something wrong here?
> 

Ah right, we're talking about the userspace API here, never mind.

> > The only exception is for 32-bit accesses to 64-bit registers, where you
> > have to return either the upper or lower 32-bits.  I think you can still
> > use extract_bytes() there should you be so inclined.
> 
> Yeah, in fact GICR_TYPER and GICD_IROUTER are the only users remaining
> afterwards. So I moved the declaration into vgic-mmio-v3.c and renamed
> it to extract_words() on the way.

did you modify it to only work on words and let len specify the length
in words then, or?

> Will send the patch in a minute ...
> 
I guess I can comment on it there.

-Christoffer