Re: [PATCH v3 30/37] drm/i915: Introduce DRM_I915_GEM_MMAP_OFFSET

Chris Wilson
2019-08-10T11:32:38Z

Quoting Matthew Auld (2019-08-09 23:26:36)
> From: Abdiel Janulgue <abdiel.janulgue@linux.intel.com>
>
> Add a new CPU mmap implementation that allows multiple fault handlers
> that depends on the object's backing pages.
>
> Note that we multiplex mmap_gtt and mmap_offset through the same ioctl,
> and use the zero extending behaviour of drm to differentiate between
> them, when we inspect the flags.
>
> Signed-off-by: Abdiel Janulgue <abdiel.janulgue@linux.intel.com>
> Signed-off-by: Matthew Auld <matthew.auld@intel.com>
> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> ---
> drivers/gpu/drm/i915/gem/i915_gem_ioctls.h | 2 ++
> drivers/gpu/drm/i915/gem/i915_gem_mman.c | 30 ++++++++++++++++++
> .../gpu/drm/i915/gem/i915_gem_object_types.h | 3 ++
> drivers/gpu/drm/i915/i915_drv.c | 2 +-
> drivers/gpu/drm/i915/i915_getparam.c | 1 +
> include/uapi/drm/i915_drm.h | 31 +++++++++++++++++++
> 6 files changed, 68 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ioctls.h b/drivers/gpu/drm/i915/gem/i915_gem_ioctls.h
> index ddc7f2a52b3e..5abd5b2172f2 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_ioctls.h
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_ioctls.h
> @@ -30,6 +30,8 @@ int i915_gem_mmap_ioctl(struct drm_device *dev, void *data,
> struct drm_file *file);
> int i915_gem_mmap_gtt_ioctl(struct drm_device *dev, void *data,
> struct drm_file *file);
> +int i915_gem_mmap_offset_ioctl(struct drm_device *dev, void *data,
> + struct drm_file *file_priv);

mmap_offset_ioctl is replacing mmap_gtt_ioctl, you don't need to keep
the old one public.

(Or vice versa apparently.)

> int i915_gem_pread_ioctl(struct drm_device *dev, void *data,
> struct drm_file *file);
> int i915_gem_pwrite_ioctl(struct drm_device *dev, void *data,
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_mman.c b/drivers/gpu/drm/i915/gem/i915_gem_mman.c
> index d4a9d59803a7..a62657a1f011 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_mman.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_mman.c
> @@ -538,12 +538,42 @@ i915_gem_mmap_gtt_ioctl(struct drm_device *dev, void *data,
> struct drm_file *file)
> {
> struct drm_i915_gem_mmap_offset *args = data;
> + struct drm_i915_private *i915 = to_i915(dev);
> +
> + if (args->flags & I915_MMAP_OFFSET_FLAGS)
> + return i915_gem_mmap_offset_ioctl(dev, data, file);
> +
> + if (!HAS_MAPPABLE_APERTURE(i915)) {
> + DRM_ERROR("No aperture, cannot mmap via legacy GTT\n");
> + return -ENODEV;
> + }
>
> return __assign_gem_object_mmap_data(file, args->handle,
> I915_MMAP_TYPE_GTT,
> &args->offset);
> }
>
> +int i915_gem_mmap_offset_ioctl(struct drm_device *dev, void *data,
> + struct drm_file *file)
> +{
> + struct drm_i915_gem_mmap_offset *args = data;
> + enum i915_mmap_type type;
> +
> + if ((args->flags & (I915_MMAP_OFFSET_WC | I915_MMAP_OFFSET_WB)) &&
> + !boot_cpu_has(X86_FEATURE_PAT))
> + return -ENODEV;
> +
> + if (args->flags & I915_MMAP_OFFSET_WC)
> + type = I915_MMAP_TYPE_OFFSET_WC;
> + else if (args->flags & I915_MMAP_OFFSET_WB)
> + type = I915_MMAP_TYPE_OFFSET_WB;
> + else if (args->flags & I915_MMAP_OFFSET_UC)
> + type = I915_MMAP_TYPE_OFFSET_UC;
> +
> + return __assign_gem_object_mmap_data(file, args->handle, type,
> + &args->offset);
> +}
> +
> void i915_mmap_offset_object_release(struct kref *ref)
> {
> struct i915_mmap_offset *mmo = container_of(ref,
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object_types.h b/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
> index a3745f7d57a1..4ea78d3c92a9 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
> @@ -64,6 +64,9 @@ struct drm_i915_gem_object_ops {
>
> enum i915_mmap_type {
> I915_MMAP_TYPE_GTT = 0,
> + I915_MMAP_TYPE_OFFSET_WC,
> + I915_MMAP_TYPE_OFFSET_WB,
> + I915_MMAP_TYPE_OFFSET_UC,
> };
>
> struct i915_mmap_offset {
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index fcee06ed3469..cf390092c927 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -2710,7 +2710,7 @@ static const struct drm_ioctl_desc i915_ioctls[] = {
> DRM_IOCTL_DEF_DRV(I915_GEM_PREAD, i915_gem_pread_ioctl, DRM_RENDER_ALLOW),
> DRM_IOCTL_DEF_DRV(I915_GEM_PWRITE, i915_gem_pwrite_ioctl, DRM_RENDER_ALLOW),
> DRM_IOCTL_DEF_DRV(I915_GEM_MMAP, i915_gem_mmap_ioctl, DRM_RENDER_ALLOW),
> - DRM_IOCTL_DEF_DRV(I915_GEM_MMAP_GTT, i915_gem_mmap_gtt_ioctl, DRM_RENDER_ALLOW),
> + DRM_IOCTL_DEF_DRV(I915_GEM_MMAP_OFFSET, i915_gem_mmap_gtt_ioctl, DRM_RENDER_ALLOW),
> DRM_IOCTL_DEF_DRV(I915_GEM_SET_DOMAIN, i915_gem_set_domain_ioctl, DRM_RENDER_ALLOW),
> DRM_IOCTL_DEF_DRV(I915_GEM_SW_FINISH, i915_gem_sw_finish_ioctl, DRM_RENDER_ALLOW),
> DRM_IOCTL_DEF_DRV(I915_GEM_SET_TILING, i915_gem_set_tiling_ioctl, DRM_RENDER_ALLOW),
> diff --git a/drivers/gpu/drm/i915/i915_getparam.c b/drivers/gpu/drm/i915/i915_getparam.c
> index 5d9101376a3d..28120249a250 100644
> --- a/drivers/gpu/drm/i915/i915_getparam.c
> +++ b/drivers/gpu/drm/i915/i915_getparam.c
> @@ -130,6 +130,7 @@ int i915_getparam_ioctl(struct drm_device *dev, void *data,
> case I915_PARAM_HAS_EXEC_BATCH_FIRST:
> case I915_PARAM_HAS_EXEC_FENCE_ARRAY:
> case I915_PARAM_HAS_EXEC_SUBMIT_FENCE:
> + case I915_PARAM_MMAP_OFFSET_VERSION:

Funny. You do realise this is just MMAP_GT_VERSION for the new struct +
ABI.

> /* For the time being all of these are always true;
> * if some supported hardware does not have one of these
> * features this value needs to be provided from
> diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
> index 469dc512cca3..fb84aed10825 100644
> --- a/include/uapi/drm/i915_drm.h
> +++ b/include/uapi/drm/i915_drm.h
> @@ -359,6 +359,7 @@ typedef struct _drm_i915_sarea {
> #define DRM_I915_QUERY 0x39
> #define DRM_I915_GEM_VM_CREATE 0x3a
> #define DRM_I915_GEM_VM_DESTROY 0x3b
> +#define DRM_I915_GEM_MMAP_OFFSET DRM_I915_GEM_MMAP_GTT
> /* Must be kept compact -- no holes */
>
> #define DRM_IOCTL_I915_INIT DRM_IOW( DRM_COMMAND_BASE + DRM_I915_INIT, drm_i915_init_t)
> @@ -421,6 +422,7 @@ typedef struct _drm_i915_sarea {
> #define DRM_IOCTL_I915_QUERY DRM_IOWR(DRM_COMMAND_BASE + DRM_I915_QUERY, struct drm_i915_query)
> #define DRM_IOCTL_I915_GEM_VM_CREATE DRM_IOWR(DRM_COMMAND_BASE + DRM_I915_GEM_VM_CREATE, struct drm_i915_gem_vm_control)
> #define DRM_IOCTL_I915_GEM_VM_DESTROY DRM_IOW (DRM_COMMAND_BASE + DRM_I915_GEM_VM_DESTROY, struct drm_i915_gem_vm_control)
> +#define DRM_IOCTL_I915_GEM_MMAP_OFFSET DRM_IOWR(DRM_COMMAND_BASE + DRM_I915_GEM_MMAP_OFFSET, struct drm_i915_gem_mmap_offset)
>
> /* Allow drivers to submit batchbuffers directly to hardware, relying
> * on the security mechanisms provided by hardware.
> @@ -611,6 +613,10 @@ typedef struct drm_i915_irq_wait {
> * See I915_EXEC_FENCE_OUT and I915_EXEC_FENCE_SUBMIT.
> */
> #define I915_PARAM_HAS_EXEC_SUBMIT_FENCE 53
> +
> +/* Mmap offset ioctl */
> +#define I915_PARAM_MMAP_OFFSET_VERSION 54

No, it's just MMAP_GTT_VERSION.

> /* Must be kept compact -- no holes and well documented */
>
> typedef struct drm_i915_getparam {
> @@ -786,6 +792,31 @@ struct drm_i915_gem_mmap_gtt {
> __u64 offset;
> };
>
> +struct drm_i915_gem_mmap_offset {
> + /** Handle for the object being mapped. */
> + __u32 handle;
> + __u32 pad;
> + /**
> + * Fake offset to use for subsequent mmap call
> + *
> + * This is a fixed-size type for 32/64 compatibility.
> + */
> + __u64 offset;
> +
> + /**
> + * Flags for extended behaviour.
> + *
> + * It is mandatory that either one of the _WC/_WB flags
> + * should be passed here.
> + */
> + __u64 flags;
> +#define I915_MMAP_OFFSET_WC (1 << 0)
> +#define I915_MMAP_OFFSET_WB (1 << 1)
> +#define I915_MMAP_OFFSET_UC (1 << 2)
> +#define I915_MMAP_OFFSET_FLAGS \
> + (I915_MMAP_OFFSET_WC | I915_MMAP_OFFSET_WB | I915_MMAP_OFFSET_UC)

You missed the extension struct.

> +};
> +
> struct drm_i915_gem_set_domain {
> /** Handle for the object */
> __u32 handle;
> --
> 2.20.1
>
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