Re: [PATCH v3 17/19] drm/xe/uapi: Add UAPI for querying VMA count and memory attributes

["Souza, Jose" <jose.souza@intel.com>]

On Tue, 2025-05-27 at 22:10 +0530, Himal Prasad Ghimiray wrote:
> Introduce the DRM_IOCTL_XE_VM_QUERY_VMAS_ATTRS ioctl to allow userspace
> to query memory attributes of VMAs within a specified virtual address
> range.
> If num_vmas == 0 and vector_of_vma_mem_attr == NULL, the ioctl returns
> the number of VMAs in the specified range.
> If num_vmas > 0 and a valid user pointer is provided in
> vector_of_vma_mem_attr, the ioctl fills the buffer with memory
> attributes for each VMA.
> This two-step interface allows userspace to first query the required
> buffer size, then retrieve detailed attributes efficiently.
> 
> v2 (Matthew Brost)
> - Use same ioctl to overload functionality
> 
> Signed-off-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
> ---
>  drivers/gpu/drm/xe/xe_device.c |  1 +
>  drivers/gpu/drm/xe/xe_vm.c     | 87 ++++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/xe/xe_vm.h     |  2 +-
>  include/uapi/drm/xe_drm.h      | 82 ++++++++++++++++++++++++++++++++
>  4 files changed, 171 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_device.c b/drivers/gpu/drm/xe/xe_device.c
> index b9791c614749..8c965d15c187 100644
> --- a/drivers/gpu/drm/xe/xe_device.c
> +++ b/drivers/gpu/drm/xe/xe_device.c
> @@ -199,6 +199,7 @@ static const struct drm_ioctl_desc xe_ioctls[] = {
>  			  DRM_RENDER_ALLOW),
>  	DRM_IOCTL_DEF_DRV(XE_OBSERVATION, xe_observation_ioctl, DRM_RENDER_ALLOW),
>  	DRM_IOCTL_DEF_DRV(XE_MADVISE, xe_vm_madvise_ioctl, DRM_RENDER_ALLOW),
> +	DRM_IOCTL_DEF_DRV(XE_VM_QUERY_VMAS_ATTRS, xe_vm_query_vmas_attrs_ioctl, DRM_RENDER_ALLOW),
>  };
>  
>  static long xe_drm_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
> diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c
> index 4520e475399e..9611d7ca2bed 100644
> --- a/drivers/gpu/drm/xe/xe_vm.c
> +++ b/drivers/gpu/drm/xe/xe_vm.c
> @@ -2162,6 +2162,93 @@ int xe_vm_destroy_ioctl(struct drm_device *dev, void *data,
>  	return err;
>  }
>  
> +static void xe_vm_query_vmas(struct xe_vm *vm, u32 *num_vmas, u64 start, u64 end)
> +{
> +	struct drm_gpuva *gpuva;
> +
> +	lockdep_assert_held(&vm->lock);
> +	drm_gpuvm_for_each_va_range(gpuva, &vm->gpuvm, start, end)
> +		(*num_vmas)++;
> +}
> +
> +static int get_mem_attrs(struct xe_vm *vm, u32 *num_vmas, u64 start,
> +			 u64 end, struct drm_xe_vma_mem_attr *mem_attrs)
> +{
> +	struct drm_gpuva *gpuva;
> +	int i = 0;
> +
> +	lockdep_assert_held(&vm->lock);
> +
> +	drm_gpuvm_for_each_va_range(gpuva, &vm->gpuvm, start, end) {
> +		struct xe_vma *vma = gpuva_to_vma(gpuva);
> +
> +		if (i == *num_vmas)
> +			return -EINVAL;
> +
> +		mem_attrs[i].start = xe_vma_start(vma);
> +		mem_attrs[i].end = xe_vma_end(vma);
> +		mem_attrs[i].atomic.val = vma->attr.atomic_access;
> +		mem_attrs[i].pat_index.val = vma->attr.pat_index;
> +		mem_attrs[i].preferred_mem_loc.devmem_fd = vma->attr.preferred_loc.devmem_fd;
> +		mem_attrs[i].preferred_mem_loc.migration_policy = vma->attr.preferred_loc.migration_policy;
> +
> +		i++;
> +	}
> +
> +	if (i <  (*num_vmas - 1))
> +		*num_vmas = i;
> +	return 0;
> +}
> +
> +int xe_vm_query_vmas_attrs_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
> +{
> +	struct xe_device *xe = to_xe_device(dev);
> +	struct xe_file *xef = to_xe_file(file);
> +	struct drm_xe_vma_mem_attr *mem_attrs;
> +	struct drm_xe_vm_query_vmas_attr *args = data;
> +	u64 __user *attrs_user = NULL;
> +	struct xe_vm *vm;
> +	int err = 0;
> +
> +	if (XE_IOCTL_DBG(xe, args->num_vmas < 0))
> +		return -EINVAL;
> +
> +	vm = xe_vm_lookup(xef, args->vm_id);
> +	if (XE_IOCTL_DBG(xe, !vm))
> +		return -EINVAL;
> +
> +	down_read(&vm->lock);
> +
> +	attrs_user = u64_to_user_ptr(args->vector_of_vma_mem_attr);
> +
> +	if (args->num_vmas == 0 && !attrs_user) {
> +		xe_vm_query_vmas(vm, &args->num_vmas, args->start, args->start + args->range);
> +		goto unlock_vm;
> +	}
> +
> +	mem_attrs = kvmalloc_array(args->num_vmas, sizeof(struct drm_xe_vma_mem_attr),
> +				   GFP_KERNEL | __GFP_ACCOUNT |
> +				   __GFP_RETRY_MAYFAIL | __GFP_NOWARN);
> +	if (!mem_attrs) {
> +		err = args->num_vmas > 1 ? -ENOBUFS : -ENOMEM;
> +		goto unlock_vm;
> +	}
> +
> +	err = get_mem_attrs(vm, &args->num_vmas, args->start,
> +			    args->start + args->range, mem_attrs);
> +	if (err)
> +		goto free_mem_attrs;
> +
> +	err = __copy_to_user(attrs_user, mem_attrs,
> +			     sizeof(struct drm_xe_vma_mem_attr) * args->num_vmas);
> +
> +free_mem_attrs:
> +	kvfree(mem_attrs);
> +unlock_vm:
> +	up_read(&vm->lock);
> +	return err;
> +}
> +
>  static bool vma_matches(struct xe_vma *vma, u64 page_addr)
>  {
>  	if (page_addr > xe_vma_end(vma) - 1 ||
> diff --git a/drivers/gpu/drm/xe/xe_vm.h b/drivers/gpu/drm/xe/xe_vm.h
> index 340ac34936f4..b1e94b536c80 100644
> --- a/drivers/gpu/drm/xe/xe_vm.h
> +++ b/drivers/gpu/drm/xe/xe_vm.h
> @@ -195,7 +195,7 @@ int xe_vm_destroy_ioctl(struct drm_device *dev, void *data,
>  			struct drm_file *file);
>  int xe_vm_bind_ioctl(struct drm_device *dev, void *data,
>  		     struct drm_file *file);
> -
> +int xe_vm_query_vmas_attrs_ioctl(struct drm_device *dev, void *data, struct drm_file *file);
>  void xe_vm_close_and_put(struct xe_vm *vm);
>  
>  static inline bool xe_vm_in_fault_mode(struct xe_vm *vm)
> diff --git a/include/uapi/drm/xe_drm.h b/include/uapi/drm/xe_drm.h
> index 03adfdc20dde..6ff9ff0c09dd 100644
> --- a/include/uapi/drm/xe_drm.h
> +++ b/include/uapi/drm/xe_drm.h
> @@ -82,6 +82,7 @@ extern "C" {
>   *  - &DRM_IOCTL_XE_WAIT_USER_FENCE
>   *  - &DRM_IOCTL_XE_OBSERVATION
>   *  - &DRM_IOCTL_XE_MADVISE
> + *  - &DRM_IOCTL_XE_VM_QUERY_VMAS_ATTRS
>   */
>  
>  /*
> @@ -104,6 +105,7 @@ extern "C" {
>  #define DRM_XE_WAIT_USER_FENCE		0x0a
>  #define DRM_XE_OBSERVATION		0x0b
>  #define DRM_XE_MADVISE			0x0c
> +#define DRM_XE_VM_QUERY_VMAS_ATTRS	0x0d
>  
>  /* Must be kept compact -- no holes */
>  
> @@ -120,6 +122,7 @@ extern "C" {
>  #define DRM_IOCTL_XE_WAIT_USER_FENCE		DRM_IOWR(DRM_COMMAND_BASE + DRM_XE_WAIT_USER_FENCE, struct drm_xe_wait_user_fence)
>  #define DRM_IOCTL_XE_OBSERVATION		DRM_IOW(DRM_COMMAND_BASE + DRM_XE_OBSERVATION, struct drm_xe_observation_param)
>  #define DRM_IOCTL_XE_MADVISE			DRM_IOWR(DRM_COMMAND_BASE + DRM_XE_MADVISE, struct drm_xe_madvise)
> +#define DRM_IOCTL_XE_VM_QUERY_VMAS_ATTRS	DRM_IOWR(DRM_COMMAND_BASE + DRM_XE_VM_QUERY_VMAS_ATTRS, struct drm_xe_vm_query_vmas_attr)
>  
>  /**
>   * DOC: Xe IOCTL Extensions
> @@ -2066,6 +2069,85 @@ struct drm_xe_madvise {
>  
>  };
>  
> +struct drm_xe_vma_mem_attr {
> +	 /** @extensions: Pointer to the first extension struct, if any */
> +	__u64 extensions;
> +
> +	/** @start: start of the vma */
> +	__u64 start;
> +
> +	/** @size: end of the vma */
> +	__u64 end;
> +
> +	struct {
> +		struct {
> +		/** @val: value of atomic operation*/
> +			__u32 val;
> +
> +		/** @reserved: Reserved */
> +			__u32 reserved;
> +		} atomic;
> +
> +		struct {
> +		/** @val: value for DRM_XE_VMA_ATTR_PURGEABLE_STATE */
> +			__u32 val;
> +
> +		/** @reserved: Reserved */
> +			__u32 reserved;
> +		} purge_state_val;

Looks like purge_state_val is not implemented but the get uAPI looks good to me, so this part is

Acked-by: José Roberto de Souza <jose.souza@intel.com>


> +
> +		struct {
> +			/** @pat_index */
> +			__u32 val;
> +
> +			/** @reserved: Reserved */
> +			__u32 reserved;
> +		} pat_index;
> +
> +		/** @preferred_mem_loc: preferred memory location */
> +		struct {
> +			__u32 devmem_fd;
> +
> +			__u32 migration_policy;
> +		} preferred_mem_loc;
> +	};
> +
> +	 /** @reserved: Reserved */
> +	__u64 reserved[2];
> +};
> +
> +/**
> + * struct drm_xe_vm_query_vmas_attr - Input of &DRM_IOCTL_XE_VM_QUERY_MEM_ATTRIBUTES
> + *
> + * Get memory attributes to a virtual address range
> + */
> +struct drm_xe_vm_query_vmas_attr {
> +	/** @extensions: Pointer to the first extension struct, if any */
> +	__u64 extensions;
> +
> +	/** @vm_id: vm_id of the virtual range */
> +	__u32 vm_id;
> +
> +	/** @num_vmas: number of vmas in range returned in @num_vmas */
> +	__u32 num_vmas;
> +
> +	/** @start: start of the virtual address range */
> +	__u64 start;
> +
> +	/** @size: size of the virtual address range */
> +	__u64 range;
> +
> +	/**
> +	 * @vector_of_ops: userptr to array of struct
> +	 * drm_xe_vma_mem_attr
> +	 */
> +	__u64 vector_of_vma_mem_attr;
> +
> +	/** @reserved: Reserved */
> +	__u64 reserved[2];
> +
> +};
> +
>  #if defined(__cplusplus)
>  }
>  #endif