[PATCH v3 6/8] KVM: kvm-vfio: wrapper to VFIO external API device helpers

Christoffer Dall
2014-11-30T13:01:51Z

On Sun, Nov 23, 2014 at 07:35:58PM +0100, Eric Auger wrote:
> Provide wrapper functions that allow KVM-VFIO device code to
> interact with a vfio device:
> - kvm_vfio_device_get_external_user gets a handle to a struct
> vfio_device from the vfio device file descriptor and increments
> its reference counter,
> - kvm_vfio_device_put_external_user decrements the reference counter
> to a vfio device,
> - kvm_vfio_external_base_device returns a handle to the struct device
> of the vfio device.
>
> The KVM-VFIO device uses the VFIO external API device functions.
>
> Signed-off-by: Eric Auger <eric.auger@linaro.org>
>
> ---
>
> v2 -> v3:
> reword the commit message and title
>
> v1 -> v2:
> - kvm_vfio_external_get_base_device renamed into
> kvm_vfio_external_base_device
> - kvm_vfio_external_get_type removed
> ---
> arch/arm/include/asm/kvm_host.h | 5 +++++
> virt/kvm/vfio.c | 45 +++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 50 insertions(+)
>
> diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
> index 53036e2..bca5b79 100644
> --- a/arch/arm/include/asm/kvm_host.h
> +++ b/arch/arm/include/asm/kvm_host.h
> @@ -169,6 +169,11 @@ void kvm_set_spte_hva(struct kvm *kvm, unsigned long hva, pte_t pte);
> unsigned long kvm_arm_num_regs(struct kvm_vcpu *vcpu);
> int kvm_arm_copy_reg_indices(struct kvm_vcpu *vcpu, u64 __user *indices);
>
> +struct vfio_device;
> +struct vfio_device *kvm_vfio_device_get_external_user(struct file *filep);
> +void kvm_vfio_device_put_external_user(struct vfio_device *vdev);
> +struct device *kvm_vfio_external_base_device(struct vfio_device *vdev);
> +

why do we add this in kvm_host.h ?

> /* We do not have shadow page tables, hence the empty hooks */
> static inline int kvm_age_hva(struct kvm *kvm, unsigned long start,
> unsigned long end)
> diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c
> index 620e37f..6f0cc34 100644
> --- a/virt/kvm/vfio.c
> +++ b/virt/kvm/vfio.c
> @@ -60,6 +60,51 @@ static void kvm_vfio_group_put_external_user(struct vfio_group *vfio_group)
> symbol_put(vfio_group_put_external_user);
> }
>
> +struct vfio_device *kvm_vfio_device_get_external_user(struct file *filep)
> +{
> + struct vfio_device *vdev;
> + struct vfio_device *(*fn)(struct file *);
> +
> + fn = symbol_get(vfio_device_get_external_user);
> + if (!fn)
> + return ERR_PTR(-EINVAL);
> +
> + vdev = fn(filep);
> +
> + symbol_put(vfio_device_get_external_user);
> +
> + return vdev;
> +}
> +
> +void kvm_vfio_device_put_external_user(struct vfio_device *vdev)
> +{
> + void (*fn)(struct vfio_device *);
> +
> + fn = symbol_get(vfio_device_put_external_user);
> + if (!fn)
> + return;
> +
> + fn(vdev);
> +
> + symbol_put(vfio_device_put_external_user);
> +}
> +
> +struct device *kvm_vfio_external_base_device(struct vfio_device *vdev)
> +{
> + struct device *(*fn)(struct vfio_device *);
> + struct device *dev;
> +
> + fn = symbol_get(vfio_external_base_device);
> + if (!fn)
> + return NULL;
> +
> + dev = fn(vdev);
> +
> + symbol_put(vfio_external_base_device);
> +
> + return dev;
> +}
> +
> static bool kvm_vfio_group_is_coherent(struct vfio_group *vfio_group)
> {
> long (*fn)(struct vfio_group *, unsigned long);
> --
> 1.9.1
>