Re: [RFC PATCH kvmtool 05/10] vfio: Add dma map/unmap handlers

[Mostafa Saleh <smostafa@google.com>]

On Sun, May 25, 2025 at 01:19:11PM +0530, Aneesh Kumar K.V (Arm) wrote:
> Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org>
> ---
>  include/kvm/vfio.h | 4 ++--
>  vfio/core.c        | 7 +++++--
>  vfio/legacy.c      | 7 +++++--
>  3 files changed, 12 insertions(+), 6 deletions(-)
> 
> diff --git a/include/kvm/vfio.h b/include/kvm/vfio.h
> index 67a528f18d33..fed692b0f265 100644
> --- a/include/kvm/vfio.h
> +++ b/include/kvm/vfio.h
> @@ -126,8 +126,8 @@ void vfio_unmap_region(struct kvm *kvm, struct vfio_region *region);
>  int vfio_pci_setup_device(struct kvm *kvm, struct vfio_device *device);
>  void vfio_pci_teardown_device(struct kvm *kvm, struct vfio_device *vdev);
>  
> -int vfio_map_mem_range(struct kvm *kvm, __u64 host_addr, __u64 iova, __u64 size);
> -int vfio_unmap_mem_range(struct kvm *kvm, __u64 iova, __u64 size);
> +extern int (*dma_map_mem_range)(struct kvm *kvm, __u64 host_addr, __u64 iova, __u64 size);
> +extern int (*dma_unmap_mem_range)(struct kvm *kvm, __u64 iova, __u64 size);
>  
>  struct kvm_mem_bank;
>  int vfio_map_mem_bank(struct kvm *kvm, struct kvm_mem_bank *bank, void *data);
> diff --git a/vfio/core.c b/vfio/core.c
> index 2af30df3b2b9..32a8e0fe67c0 100644
> --- a/vfio/core.c
> +++ b/vfio/core.c
> @@ -10,6 +10,9 @@ int kvm_vfio_device;
>  LIST_HEAD(vfio_groups);
>  struct vfio_device *vfio_devices;
>  
> +int (*dma_map_mem_range)(struct kvm *kvm, __u64 host_addr, __u64 iova, __u64 size);
> +int (*dma_unmap_mem_range)(struct kvm *kvm, __u64 iova, __u64 size);

I think it's better to  wrap those in an ops struct, this can be set once and
in the next patches this can be used for init/exit instead of having such checks:
“if (kvm->cfg.iommufd || kvm->cfg.iommufd_vdevice)”

Thanks,
Mostafa

> +
>  static int vfio_device_pci_parser(const struct option *opt, char *arg,
>  				  struct vfio_device_params *dev)
>  {
> @@ -281,12 +284,12 @@ void vfio_unmap_region(struct kvm *kvm, struct vfio_region *region)
>  
>  int vfio_map_mem_bank(struct kvm *kvm, struct kvm_mem_bank *bank, void *data)
>  {
> -	return vfio_map_mem_range(kvm, (u64)bank->host_addr, bank->guest_phys_addr, bank->size);
> +	return dma_map_mem_range(kvm, (u64)bank->host_addr, bank->guest_phys_addr, bank->size);
>  }
>  
>  int vfio_unmap_mem_bank(struct kvm *kvm, struct kvm_mem_bank *bank, void *data)
>  {
> -	return vfio_unmap_mem_range(kvm, bank->guest_phys_addr, bank->size);
> +	return dma_unmap_mem_range(kvm, bank->guest_phys_addr, bank->size);
>  }
>  
>  int vfio_configure_reserved_regions(struct kvm *kvm, struct vfio_group *group)
> diff --git a/vfio/legacy.c b/vfio/legacy.c
> index 92d6d0bd5c80..5b35d6ebff69 100644
> --- a/vfio/legacy.c
> +++ b/vfio/legacy.c
> @@ -89,7 +89,7 @@ static int vfio_get_iommu_type(void)
>  	return -ENODEV;
>  }
>  
> -int vfio_map_mem_range(struct kvm *kvm, __u64 host_addr, __u64 iova, __u64 size)
> +static int legacy_vfio_map_mem_range(struct kvm *kvm, __u64 host_addr, __u64 iova, __u64 size)
>  {
>  	int ret = 0;
>  	struct vfio_iommu_type1_dma_map dma_map = {
> @@ -110,7 +110,7 @@ int vfio_map_mem_range(struct kvm *kvm, __u64 host_addr, __u64 iova, __u64 size)
>  	return ret;
>  }
>  
> -int vfio_unmap_mem_range(struct kvm *kvm, __u64 iova, __u64 size)
> +static int legacy_vfio_unmap_mem_range(struct kvm *kvm, __u64 iova, __u64 size)
>  {
>  	struct vfio_iommu_type1_dma_unmap dma_unmap = {
>  		.argsz = sizeof(dma_unmap),
> @@ -325,6 +325,9 @@ int legacy_vfio__init(struct kvm *kvm)
>  {
>  	int ret;
>  
> +	dma_map_mem_range = legacy_vfio_map_mem_range;
> +	dma_unmap_mem_range = legacy_vfio_unmap_mem_range;
> +
>  	ret = legacy_vfio_container_init(kvm);
>  	if (ret)
>  		return ret;
> -- 
> 2.43.0
>