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

From: [email-masked] (Andre Przywara)
Date: Thu, 12 May 2016 19:52:38 +0100

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?

>>
>> 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.

Cheers,
Andre.