On Wed, Oct 28, 2026 at 05:29:29PM -0700, Deborah Brouwer wrote:
> On Tue, Oct 27, 2026 at 12:41:01AM +0800, Ke Sun wrote:
> > From: Alvin Sun <[email protected]>
> >
> > Implement BO_CREATE and BO_MMAP_OFFSET so userspace can allocate GPU
> > buffers and obtain a DRM mmap offset for the generic mmap path.
> > BO_CREATE page-aligns the requested size; BO_MMAP_OFFSET rejects
> > NO_MMAP objects, which must never be CPU-mapped.
> >
> > Signed-off-by: Alvin Sun <[email protected]>
> > ---
> > drivers/gpu/drm/tyr/driver.rs | 2 ++
> > drivers/gpu/drm/tyr/file.rs | 73
> > +++++++++++++++++++++++++++++++++++++++++++
> > drivers/gpu/drm/tyr/gem.rs | 18 +++++++++--
> > 3 files changed, 90 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/tyr/driver.rs b/drivers/gpu/drm/tyr/driver.rs
> > index c0f17bc4ce2c9..f4f31b24180b4 100644
> > --- a/drivers/gpu/drm/tyr/driver.rs
> > +++ b/drivers/gpu/drm/tyr/driver.rs
> > @@ -227,6 +227,8 @@ impl drm::Driver for TyrDrmDriver {
> > (PANTHOR_VM_DESTROY, drm_panthor_vm_destroy, ioctl::RENDER_ALLOW,
> > TyrDrmFileData::vm_destroy),
> > (PANTHOR_VM_BIND, drm_panthor_vm_bind, ioctl::RENDER_ALLOW,
> > TyrDrmFileData::vm_bind),
> > (PANTHOR_VM_GET_STATE, drm_panthor_vm_get_state,
> > ioctl::RENDER_ALLOW, TyrDrmFileData::vm_get_state),
> > + (PANTHOR_BO_CREATE, drm_panthor_bo_create, ioctl::RENDER_ALLOW,
> > TyrDrmFileData::bo_create),
> > + (PANTHOR_BO_MMAP_OFFSET, drm_panthor_bo_mmap_offset,
> > ioctl::RENDER_ALLOW, TyrDrmFileData::bo_mmap_offset),
> > }
> > }
> >
> > diff --git a/drivers/gpu/drm/tyr/file.rs b/drivers/gpu/drm/tyr/file.rs
> > index 22a74b4abf3de..9ffb42f0d8851 100644
> > --- a/drivers/gpu/drm/tyr/file.rs
> > +++ b/drivers/gpu/drm/tyr/file.rs
> > @@ -250,6 +250,79 @@ pub(crate) fn vm_get_state(
> > Ok(0)
> > })
> > }
> > +
> > + pub(crate) fn bo_create(
> > + ddev: &TyrDrmDevice<Registered>,
> > + _reg_data: &TyrDrmRegistrationData<'_>,
> > + bocreate: &mut uapi::drm_panthor_bo_create,
> > + file: &TyrDrmFile,
> > + ) -> Result<u32> {
> > + if bocreate.size == 0
> > + || bocreate.pad != 0
> > + || bocreate.flags &
> > !uapi::drm_panthor_bo_flags_DRM_PANTHOR_BO_NO_MMAP != 0
> > + {
> > + dev_dbg!(
> > + ddev.as_ref(),
> > + "Invalid BO_CREATE params: size={}, pad={}, flags={:#x}\n",
> > + bocreate.size,
> > + bocreate.pad,
> > + bocreate.flags
> > + );
> > + return Err(EINVAL);
> > + }
>
> Panthor checks that both BO_WB_MMAP and BO_NO_MMAP are not
> set at the same time, should we do the same here?
Ah, I see you check that they are mutually exclusive later in the
series, you should probably just do that in this first patch
where you add bo_create. There is no reason for them to be
in separate patches.
>
> Also if only BO_WB_MMAP is set, shouldn't we return EOPNOTSUPP?
I see you accept this flag later in this same series, it would be
clearer if you just accepted the BO_WB_MMAP flag directly in this
patch, there is no reason not to support it.
>
>
> > +
> > + if bocreate.exclusive_vm_id != 0 {
> > + dev_dbg!(ddev.as_ref(), "BO_CREATE: exclusive_vm_id not
> > supported\n");
> > + return Err(EINVAL);
>
> Return EOPNOTSUPP because it's a valid request we just don't support it.
>
> > + }
> > +
> > + let size = usize::try_from(bocreate.size).map_err(|_| {
> > + dev_dbg!(
> > + ddev.as_ref(),
> > + "BO_CREATE size {:#x} too large\n",
> > + bocreate.size
> > + );
> > + EINVAL
> > + })?;
> > + let bo = crate::gem::new_object(ddev, size, bocreate.flags)?;
>
> Use file.inner_with() to access the platform device with the bound
> lifetime and then pass it to the new_object so that you can
> avoid accessing it later with an unsafe block. Something like:
>
> let bo = file.inner_with(|pfile| {
> crate::gem::new_object(
> ddev,
> pfile.reg.pdev.as_ref(),
> size,
> bocreate.flags,
> )
> })?;
>
> > + bocreate.handle = bo.create_handle(file)?;
> > + bocreate.size = bo.size() as u64;
>
> use u64::from_safe_cast(bo.size())
>
>
> > +
> > + Ok(0)
> > + }
> > +
> > + pub(crate) fn bo_mmap_offset(
> > + ddev: &TyrDrmDevice<Registered>,
> > + _reg_data: &TyrDrmRegistrationData<'_>,
> > + bommap: &mut uapi::drm_panthor_bo_mmap_offset,
> > + file: &TyrDrmFile,
> > + ) -> Result<u32> {
> > + if bommap.pad != 0 {
> > + dev_dbg!(
> > + ddev.as_ref(),
> > + "BO mmap offset pad not zero: {}\n",
> > + bommap.pad
> > + );
> > + return Err(EINVAL);
> > + }
> > +
> > + let bo = crate::gem::lookup_handle(file,
> > bommap.handle).inspect_err(|_| {
> > + dev_dbg!(ddev.as_ref(), "Invalid BO mmap handle: {}\n",
> > bommap.handle);
> > + })?;
> > + if bo.flags() & uapi::drm_panthor_bo_flags_DRM_PANTHOR_BO_NO_MMAP
> > != 0 {
> > + dev_dbg!(ddev.as_ref(), "BO mmap offset on NO_MMAP object\n");
> > + return Err(EPERM);
> > + }
> > + bommap.offset = bo.create_mmap_offset().inspect_err(|_| {
> > + dev_err!(
> > + ddev.as_ref(),
> > + "Failed to create mmap offset for handle {}\n",
> > + bommap.handle
> > + );
> > + })?;
> > +
> > + Ok(0)
> > + }
> > }
> >
> > fn vm_bind_exec_op(vm: &Vm<'_>, file: &TyrDrmFile, op: &VmBindOp) ->
> > Result {
> > diff --git a/drivers/gpu/drm/tyr/gem.rs b/drivers/gpu/drm/tyr/gem.rs
> > index 60f6363995a5a..14f3e182b98e2 100644
> > --- a/drivers/gpu/drm/tyr/gem.rs
> > +++ b/drivers/gpu/drm/tyr/gem.rs
> > @@ -38,6 +38,13 @@ pub(crate) struct BoData {
> > flags: u32,
> > }
> >
> > +impl BoData {
> > + /// Returns the flags the BO was created with.
> > + pub(crate) fn flags(&self) -> u32 {
> > + self.flags
> > + }
> > +}
> > +
> > /// Provides a way to pass arguments when creating BoData
> > /// as required by the gem::DriverObject trait.
> > pub(crate) struct BoCreateArgs {
> > @@ -57,7 +64,6 @@ fn new(_dev: &TyrDrmDevice, _size: usize, args:
> > BoCreateArgs) -> impl PinInit<Se
> > pub(crate) type Bo = gem::shmem::Object<BoData>;
> >
> > /// Create a new GEM buffer object.
> > -#[expect(dead_code)]
> > pub(crate) fn new_object(ddev: &TyrDrmDevice, size: usize, flags: u32) ->
> > Result<ARef<Bo>> {
> > if size == 0 {
> > return Err(EINVAL);
> > @@ -65,7 +71,7 @@ pub(crate) fn new_object(ddev: &TyrDrmDevice, size:
> > usize, flags: u32) -> Result
> >
> > let aligned_size =
> > size.checked_next_multiple_of(PAGE_SIZE).ok_or(EINVAL)?;
> >
> > - Bo::new(
> > + let bo = Bo::new(
> > ddev,
> > aligned_size,
> > shmem::ObjectConfig {
> > @@ -73,7 +79,13 @@ pub(crate) fn new_object(ddev: &TyrDrmDevice, size:
> > usize, flags: u32) -> Result
> > parent_resv_obj: None,
> > },
> > BoCreateArgs { flags },
> > - )
> > + )?;
> > +
> > + // SAFETY: `ddev` is bound for the duration of this call.
> > + let dev = unsafe { ddev.as_ref().as_ref().as_bound() };
>
> You can remove this unsafe block by accessing the bound device through
> file.inner_with()
>
> > + bo.sg_table(dev)?;
> > +
> > + Ok(bo)
> > }
> >
> > /// Look up a GEM object by handle for a DRM file.
> >
> > --
> > 2.43.0
> >
