Re: [PATCH v4 06/22] KVM: arm64: ITS: Implement vgic_its_has_attr_regs and attr_regs_access

[Marc Zyngier <marc.zyngier@arm.com>]

On Mon, Mar 27 2017 at 10:30:56 AM, Eric Auger <eric.auger@redhat.com> wrote:
> This patch implements vgic_its_has_attr_regs and vgic_its_attr_regs_access
> upon the MMIO framework. VGIC ITS KVM device KVM_DEV_ARM_VGIC_GRP_ITS_REGS
> group becomes functional.
>
> At least GITS_CREADR requires to differentiate a guest write action from a
> user access. As such let's introduce a new uaccess_its_write
> vgic_register_region callback.
>
> Signed-off-by: Eric Auger <eric.auger@redhat.com>
>
> ---
>
> v3 -> v4:
> - remove changes to the REGISTER_ITS_DESC macro. This will be handled in
>   subsequent patch with the introduction of a new REGISTER_ITS_DESC_UACCESS
>   macro
> - fix IIDR access and add a comment wrt full length access
> - handle endianness
> - add kvm lock and vcpus lock
> ---
>  virt/kvm/arm/vgic/vgic-its.c  | 78 +++++++++++++++++++++++++++++++++++++++++--
>  virt/kvm/arm/vgic/vgic-mmio.h |  9 +++--
>  2 files changed, 83 insertions(+), 4 deletions(-)
>
> diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
> index f687e91..9b9ea86 100644
> --- a/virt/kvm/arm/vgic/vgic-its.c
> +++ b/virt/kvm/arm/vgic/vgic-its.c
> @@ -1469,14 +1469,88 @@ static void vgic_its_destroy(struct kvm_device *kvm_dev)
>  int vgic_its_has_attr_regs(struct kvm_device *dev,
>  			   struct kvm_device_attr *attr)
>  {
> -	return -ENXIO;
> +	const struct vgic_register_region *region;
> +	struct vgic_io_device iodev = {
> +		.regions = its_registers,
> +		.nr_regions = ARRAY_SIZE(its_registers),
> +	};
> +	gpa_t offset = attr->attr;
> +
> +	region = vgic_find_mmio_region(iodev.regions,
> +				       iodev.nr_regions,
> +				       offset);
> +	if (!region)
> +		return -ENXIO;
> +
> +	return 0;
>  }
>  
>  int vgic_its_attr_regs_access(struct kvm_device *dev,
>  			      struct kvm_device_attr *attr,
>  			      u64 *reg, bool is_write)
>  {
> -	return -ENXIO;
> +	const struct vgic_register_region *region;
> +	struct vgic_io_device iodev = {
> +		.regions = its_registers,
> +		.nr_regions = ARRAY_SIZE(its_registers),
> +	};
> +	struct vgic_its *its = dev->private;
> +	gpa_t addr, offset = attr->attr;
> +	unsigned int len;
> +	unsigned long data = 0;
> +	int ret = 0;
> +
> +	/*
> +	 * Among supported registers, only GITS_CTLR (0x0) and GITS_IIDR (0x4)
> +	 * are 32 bits. Others are 64 bits.
> +	 */
> +	if ((offset < 0x8 && offset & 0x3) || (offset >= 0x8 && offset & 0x7))
> +		return -EINVAL;

Can you use the actual register names instead of raw offsets? It's
certainly be more readable.

> +
> +	mutex_lock(&dev->kvm->lock);
> +
> +	if (IS_VGIC_ADDR_UNDEF(its->vgic_its_base)) {
> +		ret = -ENXIO;
> +		goto out;
> +	}
> +
> +	region = vgic_find_mmio_region(iodev.regions,
> +				       iodev.nr_regions,
> +				       offset);
> +	if (!region) {
> +		ret = -ENXIO;
> +		goto out;
> +	}
> +
> +	if (!lock_all_vcpus(dev->kvm)) {
> +		ret = -EBUSY;
> +		goto out;
> +	}
> +
> +	addr = its->vgic_its_base + offset;
> +
> +	/*
> +	 * Only full length register accesses are supported although
> +	 * the architecture spec theoretically allows upper/lower 32
> +	 * bits to be accessed independently
> +	 */
> +	len = region->access_flags & VGIC_ACCESS_64bit ? 8 : 4;
> +
> +	if (is_write) {
> +		data = vgic_data_mmio_bus_to_host(reg, len);
> +		if (region->uaccess_its_write)
> +			region->uaccess_its_write(dev->kvm, its, addr,
> +						  len, data);
> +		else
> +			region->its_write(dev->kvm, its, addr, len, data);
> +	} else {
> +		data = region->its_read(dev->kvm, its, addr, len);
> +		vgic_data_host_to_mmio_bus(reg, len, data);
> +	}
> +	unlock_all_vcpus(dev->kvm);
> +out:
> +	mutex_unlock(&dev->kvm->lock);
> +	return ret;
>  }
>  
>  static int vgic_its_has_attr(struct kvm_device *dev,
> diff --git a/virt/kvm/arm/vgic/vgic-mmio.h b/virt/kvm/arm/vgic/vgic-mmio.h
> index 6eec91b..becc473 100644
> --- a/virt/kvm/arm/vgic/vgic-mmio.h
> +++ b/virt/kvm/arm/vgic/vgic-mmio.h
> @@ -36,8 +36,13 @@ struct vgic_register_region {
>  	};
>  	unsigned long (*uaccess_read)(struct kvm_vcpu *vcpu, gpa_t addr,
>  				      unsigned int len);
> -	void (*uaccess_write)(struct kvm_vcpu *vcpu, gpa_t addr,
> -			      unsigned int len, unsigned long val);
> +	union {
> +		void (*uaccess_write)(struct kvm_vcpu *vcpu, gpa_t addr,
> +				      unsigned int len, unsigned long val);
> +		void (*uaccess_its_write)(struct kvm *kvm, struct vgic_its *its,
> +					  gpa_t addr, unsigned int len,
> +					  unsigned long val);
> +	};
>  };
>  
>  extern struct kvm_io_device_ops kvm_io_gic_ops;

Other that that, looks good to me

Thanks,

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