Re: [RFC 09/29] drm/xe/svm: Allow unaligned addresses and ranges for prefetch

[Matthew Brost <matthew.brost@intel.com>]

On Fri, Mar 14, 2025 at 01:32:06PM +0530, Himal Prasad Ghimiray wrote:
> The SVM prefetch operation can handle unaligned addresses and range sizes.
> This commit updates the ioctl parameter checks to accommodate unaligned
> addresses and range sizes for SVM prefetch operations.
> 

Do we really want to allow unaligned to page size prefetches? That seems
rather odd use case. Was this a specific request from the UMD team?

Matt

> Signed-off-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
> ---
>  drivers/gpu/drm/xe/xe_vm.c | 18 ++++++++++++++++--
>  1 file changed, 16 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c
> index 07cad2804b14..c6343a629c02 100644
> --- a/drivers/gpu/drm/xe/xe_vm.c
> +++ b/drivers/gpu/drm/xe/xe_vm.c
> @@ -3086,6 +3086,16 @@ ALLOW_ERROR_INJECTION(vm_bind_ioctl_ops_execute, ERRNO);
>  #define XE_64K_PAGE_MASK 0xffffull
>  #define ALL_DRM_XE_SYNCS_FLAGS (DRM_XE_SYNCS_FLAG_WAIT_FOR_OP)
>  
> +static bool addr_not_in_cpu_addr_vma(struct xe_vm *vm, u64 addr)
> +{
> +	struct xe_vma *vma;
> +
> +	down_write(&vm->lock);
> +	vma = xe_vm_find_vma_by_addr(vm, addr);
> +	up_write(&vm->lock);
> +	return !xe_vma_is_cpu_addr_mirror(vma);
> +}
> +
>  static int vm_bind_ioctl_check_args(struct xe_device *xe, struct xe_vm *vm,
>  				    struct drm_xe_vm_bind *args,
>  				    struct drm_xe_vm_bind_op **bind_ops)
> @@ -3194,8 +3204,12 @@ static int vm_bind_ioctl_check_args(struct xe_device *xe, struct xe_vm *vm,
>  		}
>  
>  		if (XE_IOCTL_DBG(xe, obj_offset & ~PAGE_MASK) ||
> -		    XE_IOCTL_DBG(xe, addr & ~PAGE_MASK) ||
> -		    XE_IOCTL_DBG(xe, range & ~PAGE_MASK) ||
> +		    XE_IOCTL_DBG(xe, (addr & ~PAGE_MASK) &&
> +				 (addr_not_in_cpu_addr_vma(vm, addr) ||
> +				 op != DRM_XE_VM_BIND_OP_PREFETCH)) ||
> +		    XE_IOCTL_DBG(xe, (range & ~PAGE_MASK) &&
> +				 (addr_not_in_cpu_addr_vma(vm, addr) ||
> +				 op != DRM_XE_VM_BIND_OP_PREFETCH)) ||
>  		    XE_IOCTL_DBG(xe, !range &&
>  				 op != DRM_XE_VM_BIND_OP_UNMAP_ALL)) {
>  			err = -EINVAL;
> -- 
> 2.34.1
>