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* [PATCH v11 0/5] rust: Add support for reserving of ranges of IDs
@ 2026-11-09  8:32 Eliot Courtney
  2026-11-09  8:32 ` [PATCH v11 1/5] rust: io: use Alignment size constants Eliot Courtney
                   ` (6 more replies)
  0 siblings, 7 replies; 13+ messages in thread
From: Eliot Courtney @ 2026-11-09  8:32 UTC (permalink / raw)
  To: Alice Ryhl, Burak Emir, Yury Norov, Miguel Ojeda, Boqun Feng,
	Gary Guo, Björn Roy Baron, Benno Lossin, Andreas Hindborg,
	Trevor Gross, Danilo Krummrich, Daniel Almeida, Tamir Duberstein,
	Alexandre Courbot, Onur Özkan, David Airlie, Simona Vetter
  Cc: Greg Kroah-Hartman, John Hubbard, Alistair Popple, Timur Tabi,
	Zhi Wang, rust-for-linux, linux-kernel, nova-gpu, dri-devel,
	Eliot Courtney

Add support for reserving of ranges of IDs, with a usage in nova-core
for channel IDs.

The bitmap and `IdPool` parts from earlier versions are in v7.4-rc1
now, and this version has the remaining patches: using the `Alignment`
size constants, exact `IdPool` capacities, and `ChannelIdPool`.

Channel ID tracking is needed for allotting ranges of channel IDs to
vGPU guests, and later for regular host channel ID reservation.
nova-core needs allocation of a contiguous sequence of IDs with a
specific length and sometimes a specific alignment [1].

About the tradeoffs between different data structures:
- IDA/xarray do not support allocating a contiguous sequence of IDs
  (ida_alloc_range() allocates a single ID within a range, not a contiguous
  sequence).
- A maple tree works, but is not as good a fit. The ID space is small
  (limited to 2048) and aligned allocation needs an alloc_range()+erase() retry
  loop (plus a Mutex around it, or new mas_empty_area() bindings) that
  essentially reimplements bitmap_find_next_zero_area(). See the maple tree
  version at [2]. For 2048 IDs a bitmap is also considerably faster and smaller
  [3].
- The bitmap API natively supports aligned contiguous area allocation
  (bitmap_find_next_zero_area()).

This is based on drm-rust-next.

[1]: https://lore.kernel.org/all/84bc8bd2-e292-4b84-9580-a1b5df4c5bdc@nvidia.com/
[2]: https://lore.kernel.org/all/20260710-chid-maple-v1-1-4ee869055268@nvidia.com/
[3]: https://lore.kernel.org/all/20260717053241.916441-1-ynorov@nvidia.com/

Signed-off-by: Eliot Courtney <ecourtney@nvidia.com>
---
Changes in v11:
- Rebase on drm-rust-next (pre-reqs are merged now)
- Split patch #1 by subsystem (Danilo). Just splitting with no actual
  changes, so I kept the reviewed-by tags on the new patches
- Add reviewed-by tags
- Link to v10: https://patch.msgid.link/20261019-chid-v10-0-67de9180b4ed@nvidia.com

Changes in v10:
- Drop the patches that were applied to rust-next
- Rebase on drm-rust-next (plus pre-reqs)
- Use a capacity of 1 instead of 0 in the grow_request() example in
  patch #2 (Yury)
- Convert the remaining Alignment::new() users in nova-core in patch #1
- Link to v9: https://patch.msgid.link/20260930-chid-v9-0-0d6cca376cff@nvidia.com

Changes in v9:
- Rebase on drm-rust-next
- Moved cv! to a separate series which this now depends on
- Reference Link: tag from the text + indent code in patch #4 commit
  message (Miguel)
- Add reviewed-by tags
- Link to v8: https://patch.msgid.link/20260827-chid-v8-0-bc74c77d0214@nvidia.com

Changes in v8:
- Clarify overflow cases in patch #2 (Alex)
- Replace nz! with generalized cv! macro (Gary)
- Add cv! macro to prelude
- Split SizeConstants and adding new constants patch (Alex)
- Move alignment size constants conersions patch (Alex)
- Drop NonZero on IdPool, fix grow_request instead (Alice, Alex)
- Add shrink/grow doctests (Burak)
- Link to v7: https://patch.msgid.link/20260817-chid-v7-0-a5872e64d8f4@nvidia.com

Changes in v7:
- Add nz! macro for compile time NonZero
- Implement SizeConstants for Alignment + add sub 1k size constants
- Use Alignment constants + nz! in this series
- Add final patch converting existing callers to use Alignment constants
- Rename alloc_area/release_area -> reserve_ids / release_ids
- Link to v6: https://patch.msgid.link/20260813-chid-v6-0-160be5dfb5bd@nvidia.com

Changes in v6:
- Take a NonZero nbits in `next_zero_area_off`, `set` and `clear` (Yury)
- Remove `UnusedArea`, `IdPool::alloc_area` now allocates directly (Yury)
- Add patch: take a NonZero capacity in `IdPool::with_capacity()`
- Add patch: do not round the capacity up to `BitmapVec::MAX_INLINE_LEN`,
  which also removes the bounds check in `ChannelIdPool::alloc_area`
- Add more testing of Drop for `ChannelIdPool` (Yury)
- Link to v5: https://patch.msgid.link/20260812-chid-v5-0-6c767770b3f4@nvidia.com

Changes in v5:
- `bitmap_assert!` i32::MAX length for Bitmap::from_raw* (Yury)
- Only run overflow check on 32-bit (Yury)
- Link to v4: https://patch.msgid.link/20260810-chid-v4-0-c9f206fdcb97@nvidia.com

Changes in v4:
- Add `next_zero_area_off` to match C code (Yury)
- Replace overflow checks to match C code in bitmap-for-next.
- Tighten `Bitmap` unsafe contract to disallow Bitmaps larger than i32::MAX
- Link to v3: https://patch.msgid.link/20260729-chid-v3-0-20cc08032bbc@nvidia.com

Changes in v3:
- Use `Alignment` type in id_pool and bitmap (Alice)
- Remove hang check on the basis that it's extraordinarily rare.
- Link to v2: https://patch.msgid.link/20260723-chid-v2-0-c35e5e9fb3d9@nvidia.com

Changes in v2:
- Collected Alice's Reviewed-by on patch 1.
- Address Yury's comments w.r.t. using __bitmap_set etc directly.
- Address Yury's comments w.r.t. following the C names
- Additionally check for an overflow case that causes a hang
- Added more info to cover letter + patch 4 w.r.t. channel ID allottment
  requirements
- Add align parameter to ChannelIdPool::alloc_area() plus an aligned
  allocation test
- Add missing INVARIANT comment when constructing UnusedArea
- Link to v1:
  https://patch.msgid.link/20260703-chid-v1-0-84fe8259e46e@nvidia.com

---
Eliot Courtney (5):
      rust: io: use Alignment size constants
      rust: gpu: buddy: use Alignment size constants
      gpu: nova-core: use Alignment size constants
      rust: id_pool: do not round capacity up to BitmapVec::MAX_INLINE_LEN
      gpu: nova-core: add ChannelIdPool

 drivers/gpu/nova-core/fb.rs               |  10 +-
 drivers/gpu/nova-core/fb/hal/gb100.rs     |   2 +-
 drivers/gpu/nova-core/fsp.rs              |   4 +-
 drivers/gpu/nova-core/gpu.rs              |   9 +-
 drivers/gpu/nova-core/gpu/channel.rs      | 198 ++++++++++++++++++++++++++++++
 drivers/gpu/nova-core/gsp/fw.rs           |  12 +-
 drivers/gpu/nova-core/mm.rs               |   2 +-
 drivers/gpu/nova-core/mm/bar_user.rs      |   7 +-
 drivers/gpu/nova-core/mm/pagetable/map.rs |   7 +-
 drivers/gpu/nova-core/mm/pramin.rs        |   6 +-
 drivers/gpu/nova-core/vbios.rs            |   7 +-
 rust/kernel/gpu/buddy.rs                  |  26 ++--
 rust/kernel/id_pool.rs                    |  38 +++++-
 rust/kernel/io.rs                         |   5 +-
 14 files changed, 279 insertions(+), 54 deletions(-)
---
base-commit: 7ecd9ee29f7bfbe9a293952fbc83c3f8bd7205dd
change-id: 20260608-chid-18fa943c6d6c

Best regards,
--  
Eliot Courtney <ecourtney@nvidia.com>


^ permalink raw reply	[flat|nested] 13+ messages in thread

* [PATCH v11 1/5] rust: io: use Alignment size constants
  2026-11-09  8:32 [PATCH v11 0/5] rust: Add support for reserving of ranges of IDs Eliot Courtney
@ 2026-11-09  8:32 ` Eliot Courtney
  2026-11-09 12:37   ` Gary Guo
  2026-11-09  8:32 ` [PATCH v11 2/5] rust: gpu: buddy: " Eliot Courtney
                   ` (5 subsequent siblings)
  6 siblings, 1 reply; 13+ messages in thread
From: Eliot Courtney @ 2026-11-09  8:32 UTC (permalink / raw)
  To: Alice Ryhl, Burak Emir, Yury Norov, Miguel Ojeda, Boqun Feng,
	Gary Guo, Björn Roy Baron, Benno Lossin, Andreas Hindborg,
	Trevor Gross, Danilo Krummrich, Daniel Almeida, Tamir Duberstein,
	Alexandre Courbot, Onur Özkan, David Airlie, Simona Vetter
  Cc: Greg Kroah-Hartman, John Hubbard, Alistair Popple, Timur Tabi,
	Zhi Wang, rust-for-linux, linux-kernel, nova-gpu, dri-devel,
	Eliot Courtney

Use `SizeConstants` for Alignment that are implemented now.

Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Eliot Courtney <ecourtney@nvidia.com>
---
 rust/kernel/io.rs | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/rust/kernel/io.rs b/rust/kernel/io.rs
index a877df11a03e..31c6975376bf 100644
--- a/rust/kernel/io.rs
+++ b/rust/kernel/io.rs
@@ -21,7 +21,8 @@
     ptr::{
         Alignment,
         KnownSize, //
-    }, //
+    },
+    sizes::SizeConstants, //
 };
 
 #[cfg(CONFIG_HAS_IOMEM)]
@@ -154,7 +155,7 @@ pub fn ptr_try_from_raw_parts_mut(base: *mut u8, size: usize) -> Result<*mut Sel
 impl<const SIZE: usize> KnownSize for Region<SIZE> {
     const MIN_SIZE: usize = SIZE;
     // Alignment of 4 is the most common; different base types can be added once required.
-    const MIN_ALIGN: Alignment = Alignment::new::<4>();
+    const MIN_ALIGN: Alignment = Alignment::SZ_4;
 
     #[inline(always)]
     fn size(p: *const Self) -> usize {

-- 
2.56.0


^ permalink raw reply	[flat|nested] 13+ messages in thread

* [PATCH v11 2/5] rust: gpu: buddy: use Alignment size constants
  2026-11-09  8:32 [PATCH v11 0/5] rust: Add support for reserving of ranges of IDs Eliot Courtney
  2026-11-09  8:32 ` [PATCH v11 1/5] rust: io: use Alignment size constants Eliot Courtney
@ 2026-11-09  8:32 ` Eliot Courtney
  2026-11-09 12:37   ` Gary Guo
  2026-11-09  8:32 ` [PATCH v11 3/5] gpu: nova-core: " Eliot Courtney
                   ` (4 subsequent siblings)
  6 siblings, 1 reply; 13+ messages in thread
From: Eliot Courtney @ 2026-11-09  8:32 UTC (permalink / raw)
  To: Alice Ryhl, Burak Emir, Yury Norov, Miguel Ojeda, Boqun Feng,
	Gary Guo, Björn Roy Baron, Benno Lossin, Andreas Hindborg,
	Trevor Gross, Danilo Krummrich, Daniel Almeida, Tamir Duberstein,
	Alexandre Courbot, Onur Özkan, David Airlie, Simona Vetter
  Cc: Greg Kroah-Hartman, John Hubbard, Alistair Popple, Timur Tabi,
	Zhi Wang, rust-for-linux, linux-kernel, nova-gpu, dri-devel,
	Eliot Courtney

Use `SizeConstants` for Alignment that are implemented now.

Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Eliot Courtney <ecourtney@nvidia.com>
---
 rust/kernel/gpu/buddy.rs | 26 +++++++++++++-------------
 1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/rust/kernel/gpu/buddy.rs b/rust/kernel/gpu/buddy.rs
index d502ada6ebbd..691bb40629d4 100644
--- a/rust/kernel/gpu/buddy.rs
+++ b/rust/kernel/gpu/buddy.rs
@@ -31,11 +31,11 @@
 //! let buddy = GpuBuddy::new(GpuBuddyParams {
 //!     base_offset: 0,
 //!     size: SZ_1G as u64,
-//!     chunk_size: Alignment::new::<SZ_4K>(),
+//!     chunk_size: Alignment::SZ_4K,
 //! })?;
 //!
 //! assert_eq!(buddy.size(), SZ_1G as u64);
-//! assert_eq!(buddy.chunk_size(), Alignment::new::<SZ_4K>());
+//! assert_eq!(buddy.chunk_size(), Alignment::SZ_4K);
 //! let initial_free = buddy.avail();
 //!
 //! // Allocate 16MB. Block lands at the top of the address range.
@@ -43,7 +43,7 @@
 //!     buddy.alloc_blocks(
 //!         GpuBuddyAllocMode::Simple,
 //!         SZ_16M as u64,
-//!         Alignment::new::<SZ_16M>(),
+//!         Alignment::SZ_16M,
 //!         GpuBuddyAllocFlags::default(),
 //!     ),
 //!     GFP_KERNEL,
@@ -74,14 +74,14 @@
 //! # let buddy = GpuBuddy::new(GpuBuddyParams {
 //! #     base_offset: 0,
 //! #     size: SZ_1G as u64,
-//! #     chunk_size: Alignment::new::<SZ_4K>(),
+//! #     chunk_size: Alignment::SZ_4K,
 //! # })?;
 //! # let initial_free = buddy.avail();
 //! let topdown = KBox::pin_init(
 //!     buddy.alloc_blocks(
 //!         GpuBuddyAllocMode::TopDown,
 //!         SZ_16M as u64,
-//!         Alignment::new::<SZ_16M>(),
+//!         Alignment::SZ_16M,
 //!         GpuBuddyAllocFlags::default(),
 //!     ),
 //!     GFP_KERNEL,
@@ -114,7 +114,7 @@
 //! # let buddy = GpuBuddy::new(GpuBuddyParams {
 //! #     base_offset: 0,
 //! #     size: SZ_1G as u64,
-//! #     chunk_size: Alignment::new::<SZ_4K>(),
+//! #     chunk_size: Alignment::SZ_4K,
 //! # })?;
 //! # let initial_free = buddy.avail();
 //! // Create fragmentation by allocating 4MB blocks at [0,4M) and [8M,12M).
@@ -122,7 +122,7 @@
 //!     buddy.alloc_blocks(
 //!         GpuBuddyAllocMode::Range(0..SZ_4M as u64),
 //!         SZ_4M as u64,
-//!         Alignment::new::<SZ_4M>(),
+//!         Alignment::SZ_4M,
 //!         GpuBuddyAllocFlags::default(),
 //!     ),
 //!     GFP_KERNEL,
@@ -133,7 +133,7 @@
 //!     buddy.alloc_blocks(
 //!         GpuBuddyAllocMode::Range(SZ_8M as u64..(SZ_8M + SZ_4M) as u64),
 //!         SZ_4M as u64,
-//!         Alignment::new::<SZ_4M>(),
+//!         Alignment::SZ_4M,
 //!         GpuBuddyAllocFlags::default(),
 //!     ),
 //!     GFP_KERNEL,
@@ -145,7 +145,7 @@
 //!     buddy.alloc_blocks(
 //!         GpuBuddyAllocMode::Range(0..SZ_16M as u64),
 //!         SZ_8M as u64,
-//!         Alignment::new::<SZ_4M>(),
+//!         Alignment::SZ_4M,
 //!         GpuBuddyAllocFlags::default(),
 //!     ),
 //!     GFP_KERNEL,
@@ -178,14 +178,14 @@
 //! let small = GpuBuddy::new(GpuBuddyParams {
 //!     base_offset: 0,
 //!     size: SZ_16M as u64,
-//!     chunk_size: Alignment::new::<SZ_4K>(),
+//!     chunk_size: Alignment::SZ_4K,
 //! })?;
 //!
 //! let _hole1 = KBox::pin_init(
 //!     small.alloc_blocks(
 //!         GpuBuddyAllocMode::Range(0..SZ_4M as u64),
 //!         SZ_4M as u64,
-//!         Alignment::new::<SZ_4M>(),
+//!         Alignment::SZ_4M,
 //!         GpuBuddyAllocFlags::default(),
 //!     ),
 //!     GFP_KERNEL,
@@ -195,7 +195,7 @@
 //!     small.alloc_blocks(
 //!         GpuBuddyAllocMode::Range(SZ_8M as u64..(SZ_8M + SZ_4M) as u64),
 //!         SZ_4M as u64,
-//!         Alignment::new::<SZ_4M>(),
+//!         Alignment::SZ_4M,
 //!         GpuBuddyAllocFlags::default(),
 //!     ),
 //!     GFP_KERNEL,
@@ -206,7 +206,7 @@
 //!     small.alloc_blocks(
 //!         GpuBuddyAllocMode::Simple,
 //!         SZ_8M as u64,
-//!         Alignment::new::<SZ_4M>(),
+//!         Alignment::SZ_4M,
 //!         GpuBuddyAllocFlag::Contiguous,
 //!     ),
 //!     GFP_KERNEL,

-- 
2.56.0


^ permalink raw reply	[flat|nested] 13+ messages in thread

* [PATCH v11 3/5] gpu: nova-core: use Alignment size constants
  2026-11-09  8:32 [PATCH v11 0/5] rust: Add support for reserving of ranges of IDs Eliot Courtney
  2026-11-09  8:32 ` [PATCH v11 1/5] rust: io: use Alignment size constants Eliot Courtney
  2026-11-09  8:32 ` [PATCH v11 2/5] rust: gpu: buddy: " Eliot Courtney
@ 2026-11-09  8:32 ` Eliot Courtney
  2026-11-09 12:37   ` Gary Guo
  2026-11-09  8:32 ` [PATCH v11 4/5] rust: id_pool: do not round capacity up to BitmapVec::MAX_INLINE_LEN Eliot Courtney
                   ` (3 subsequent siblings)
  6 siblings, 1 reply; 13+ messages in thread
From: Eliot Courtney @ 2026-11-09  8:32 UTC (permalink / raw)
  To: Alice Ryhl, Burak Emir, Yury Norov, Miguel Ojeda, Boqun Feng,
	Gary Guo, Björn Roy Baron, Benno Lossin, Andreas Hindborg,
	Trevor Gross, Danilo Krummrich, Daniel Almeida, Tamir Duberstein,
	Alexandre Courbot, Onur Özkan, David Airlie, Simona Vetter
  Cc: Greg Kroah-Hartman, John Hubbard, Alistair Popple, Timur Tabi,
	Zhi Wang, rust-for-linux, linux-kernel, nova-gpu, dri-devel,
	Eliot Courtney

Use `SizeConstants` for Alignment that are implemented now.

Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Eliot Courtney <ecourtney@nvidia.com>
---
 drivers/gpu/nova-core/fb.rs               | 10 +++++-----
 drivers/gpu/nova-core/fb/hal/gb100.rs     |  2 +-
 drivers/gpu/nova-core/fsp.rs              |  4 ++--
 drivers/gpu/nova-core/gpu.rs              |  7 ++-----
 drivers/gpu/nova-core/gsp/fw.rs           | 12 +++---------
 drivers/gpu/nova-core/mm.rs               |  2 +-
 drivers/gpu/nova-core/mm/bar_user.rs      |  7 ++++---
 drivers/gpu/nova-core/mm/pagetable/map.rs |  7 +++++--
 drivers/gpu/nova-core/mm/pramin.rs        |  6 +++---
 drivers/gpu/nova-core/vbios.rs            |  7 +++++--
 10 files changed, 31 insertions(+), 33 deletions(-)

diff --git a/drivers/gpu/nova-core/fb.rs b/drivers/gpu/nova-core/fb.rs
index b0c0b8fe6008..5ceb7760c78e 100644
--- a/drivers/gpu/nova-core/fb.rs
+++ b/drivers/gpu/nova-core/fb.rs
@@ -219,7 +219,7 @@ pub(crate) fn new(
         };
 
         let frts = {
-            const FRTS_DOWN_ALIGN: Alignment = Alignment::new::<SZ_128K>();
+            const FRTS_DOWN_ALIGN: Alignment = Alignment::SZ_128K;
             let frts_size: u64 = hal.frts_size();
             let frts_base = vga_workspace.start.align_down(FRTS_DOWN_ALIGN) - frts_size;
 
@@ -227,7 +227,7 @@ pub(crate) fn new(
         };
 
         let boot = {
-            const BOOTLOADER_DOWN_ALIGN: Alignment = Alignment::new::<SZ_4K>();
+            const BOOTLOADER_DOWN_ALIGN: Alignment = Alignment::SZ_4K;
             let bootloader_size = u64::from_safe_cast(gsp_fw.bootloader.ucode.size());
             let bootloader_base = (frts.start - bootloader_size).align_down(BOOTLOADER_DOWN_ALIGN);
 
@@ -235,7 +235,7 @@ pub(crate) fn new(
         };
 
         let fw_image = {
-            const FW_IMAGE_DOWN_ALIGN: Alignment = Alignment::new::<SZ_64K>();
+            const FW_IMAGE_DOWN_ALIGN: Alignment = Alignment::SZ_64K;
             let fw_image_size = u64::from_safe_cast(gsp_fw.size());
             let fw_image_addr = (boot.start - fw_image_size).align_down(FW_IMAGE_DOWN_ALIGN);
 
@@ -245,7 +245,7 @@ pub(crate) fn new(
         let (vf_partition_count, wpr2_heap_size) = wpr2_heap_params(chipset, vgpu_state, fb.end)?;
 
         let wpr2_heap = {
-            const WPR2_HEAP_DOWN_ALIGN: Alignment = Alignment::new::<SZ_1M>();
+            const WPR2_HEAP_DOWN_ALIGN: Alignment = Alignment::SZ_1M;
             let wpr2_heap_addr = fw_image
                 .start
                 .checked_sub(wpr2_heap_size)
@@ -256,7 +256,7 @@ pub(crate) fn new(
         };
 
         let wpr2 = {
-            const WPR2_DOWN_ALIGN: Alignment = Alignment::new::<SZ_1M>();
+            const WPR2_DOWN_ALIGN: Alignment = Alignment::SZ_1M;
             let wpr2_addr = (wpr2_heap.start - u64::from_safe_cast(size_of::<gsp::GspFwWprMeta>()))
                 .align_down(WPR2_DOWN_ALIGN);
 
diff --git a/drivers/gpu/nova-core/fb/hal/gb100.rs b/drivers/gpu/nova-core/fb/hal/gb100.rs
index 612f70333c11..37b2ae762df4 100644
--- a/drivers/gpu/nova-core/fb/hal/gb100.rs
+++ b/drivers/gpu/nova-core/fb/hal/gb100.rs
@@ -80,7 +80,7 @@ fn write_sysmem_flush_page_gb100(hshub0: Mmio<'_, regs::Hshub0Registers>, addr:
 
 // This PMU reservation size is r570-specific.
 pub(super) const fn pmu_reserved_size_gb100() -> u32 {
-    cv!(const_align_up(SZ_8M + SZ_16M + SZ_4K, Alignment::new::<SZ_128K>()).unwrap())
+    cv!(const_align_up(SZ_8M + SZ_16M + SZ_4K, Alignment::SZ_128K).unwrap())
 }
 
 impl FbHal for Gb100 {
diff --git a/drivers/gpu/nova-core/fsp.rs b/drivers/gpu/nova-core/fsp.rs
index 3a4a10487f33..637a00b2c951 100644
--- a/drivers/gpu/nova-core/fsp.rs
+++ b/drivers/gpu/nova-core/fsp.rs
@@ -20,7 +20,7 @@
         Alignable,
         Alignment, //
     },
-    sizes::SZ_2M,
+    sizes::SizeConstants,
     time::Delta,
     transmute::{
         AsBytes,
@@ -259,7 +259,7 @@ fn frts_vidmem_offset(hal: &dyn hal::FspHal, fb_info: &FbSizes) -> Result<u64> {
         if fb_info.pmu_reserved_size != 0 {
             offset = (offset + u64::from(fb_info.pmu_reserved_size))
                 // The 2 MiB alignment is r570-specific.
-                .align_up(Alignment::new::<SZ_2M>())
+                .align_up(Alignment::SZ_2M)
                 .ok_or(EINVAL)?;
         }
 
diff --git a/drivers/gpu/nova-core/gpu.rs b/drivers/gpu/nova-core/gpu.rs
index ac5305d7ff5e..d185e927233f 100644
--- a/drivers/gpu/nova-core/gpu.rs
+++ b/drivers/gpu/nova-core/gpu.rs
@@ -12,10 +12,7 @@
     pci,
     prelude::*,
     ptr::Alignment,
-    sizes::{
-        SizeConstants,
-        SZ_4K, //
-    },
+    sizes::SizeConstants,
     uapi, //
 };
 
@@ -568,7 +565,7 @@ pub(crate) fn new<'a>(
                 let buddy_params = GpuBuddyParams {
                     base_offset: usable_vram.start,
                     size: usable_vram.end - usable_vram.start,
-                    chunk_size: Alignment::new::<SZ_4K>(),
+                    chunk_size: Alignment::SZ_4K,
                 };
 
                 GpuMm::new(
diff --git a/drivers/gpu/nova-core/gsp/fw.rs b/drivers/gpu/nova-core/gsp/fw.rs
index 75b98f24dea1..5c216d777dff 100644
--- a/drivers/gpu/nova-core/gsp/fw.rs
+++ b/drivers/gpu/nova-core/gsp/fw.rs
@@ -26,10 +26,7 @@
         Alignment,
         KnownSize, //
     },
-    sizes::{
-        SizeConstants,
-        SZ_128K, //
-    },
+    sizes::SizeConstants,
     transmute::{
         AsBytes,
         FromBytes, //
@@ -65,7 +62,7 @@
 enum GspFwHeapParams {}
 
 /// Minimum required alignment for the GSP heap.
-const GSP_HEAP_ALIGNMENT: Alignment = Alignment::new::<{ 1 << 20 }>();
+const GSP_HEAP_ALIGNMENT: Alignment = Alignment::SZ_1M;
 
 impl GspFwHeapParams {
     /// Returns the amount of GSP-RM heap memory used during GSP-RM boot and initialization (up to
@@ -209,10 +206,7 @@ pub(crate) fn from_ranges<'a>(
             bootBinOffset: ranges.boot.start,
             frtsOffset: ranges.frts.start,
             frtsSize: ranges.frts.len(),
-            gspFwWprEnd: ranges
-                .vga_workspace
-                .start
-                .align_down(Alignment::new::<SZ_128K>()),
+            gspFwWprEnd: ranges.vga_workspace.start.align_down(Alignment::SZ_128K),
             gspFwHeapVfPartitionCount: ranges.vf_partition_count,
             fbSize: ranges.fb.len(),
             vgaWorkspaceOffset: ranges.vga_workspace.start,
diff --git a/drivers/gpu/nova-core/mm.rs b/drivers/gpu/nova-core/mm.rs
index 8a934c55169f..f53886f9ed91 100644
--- a/drivers/gpu/nova-core/mm.rs
+++ b/drivers/gpu/nova-core/mm.rs
@@ -317,7 +317,7 @@ pub(crate) fn run(
 
         let base = usable_fb_regions.iter().find_map(|region| {
             // Tests rely on this being 8 byte aligned for checking misalignment handling.
-            let base = region.start.align_up(Alignment::new::<8>())?;
+            let base = region.start.align_up(Alignment::SZ_8)?;
             (base.checked_add(SELFTEST_SPAN)? <= region.end).then_some(base)
         });
         let Some(base) = base else {
diff --git a/drivers/gpu/nova-core/mm/bar_user.rs b/drivers/gpu/nova-core/mm/bar_user.rs
index 6e9384f06f43..2e8bd2a8ed91 100644
--- a/drivers/gpu/nova-core/mm/bar_user.rs
+++ b/drivers/gpu/nova-core/mm/bar_user.rs
@@ -195,6 +195,7 @@ pub(crate) fn run_self_test(
         },
         ptr::Alignment,
         sizes::{
+            SizeConstants,
             SZ_16K,
             SZ_32K,
             SZ_4K,
@@ -222,7 +223,7 @@ pub(crate) fn run_self_test(
         mm.buddy().alloc_blocks(
             GpuBuddyAllocMode::Simple,
             SZ_4K.into_safe_cast(),
-            Alignment::new::<SZ_4K>(),
+            Alignment::SZ_4K,
             GpuBuddyAllocFlags::default(),
         ),
         GFP_KERNEL,
@@ -299,7 +300,7 @@ pub(crate) fn run_self_test(
         mm.buddy().alloc_blocks(
             GpuBuddyAllocMode::Range(range_base + sz_16k..range_base + sz_16k + sz_4k),
             SZ_4K.into_safe_cast(),
-            Alignment::new::<SZ_4K>(),
+            Alignment::SZ_4K,
             GpuBuddyAllocFlags::default(),
         ),
         GFP_KERNEL,
@@ -311,7 +312,7 @@ pub(crate) fn run_self_test(
         mm.buddy().alloc_blocks(
             GpuBuddyAllocMode::Range(range_base..range_base + sz_32k_4k),
             SZ_32K.into_safe_cast(),
-            Alignment::new::<SZ_4K>(),
+            Alignment::SZ_4K,
             GpuBuddyAllocFlags::default(),
         ),
         GFP_KERNEL,
diff --git a/drivers/gpu/nova-core/mm/pagetable/map.rs b/drivers/gpu/nova-core/mm/pagetable/map.rs
index 77431c509a89..f7774b9cc972 100644
--- a/drivers/gpu/nova-core/mm/pagetable/map.rs
+++ b/drivers/gpu/nova-core/mm/pagetable/map.rs
@@ -17,7 +17,10 @@
         RBTree,
         RBTreeNode, //
     },
-    sizes::SZ_4K, //
+    sizes::{
+        SizeConstants,
+        SZ_4K, //
+    }, //
 };
 
 use super::{
@@ -84,7 +87,7 @@ fn alloc_and_zero_page(mm: &mut GpuMm<'_>, level: PageTableLevel) -> Result<Prep
             mm.buddy().alloc_blocks(
                 GpuBuddyAllocMode::Simple,
                 SZ_4K.into_safe_cast(),
-                Alignment::new::<SZ_4K>(),
+                Alignment::SZ_4K,
                 GpuBuddyAllocFlags::default(),
             ),
             GFP_KERNEL,
diff --git a/drivers/gpu/nova-core/mm/pramin.rs b/drivers/gpu/nova-core/mm/pramin.rs
index 7f89c093d591..c83b1681d241 100644
--- a/drivers/gpu/nova-core/mm/pramin.rs
+++ b/drivers/gpu/nova-core/mm/pramin.rs
@@ -19,8 +19,8 @@
         Alignment, //
     },
     sizes::{
-        SZ_1M,
-        SZ_64K, //
+        SizeConstants,
+        SZ_1M, //
     },
 };
 
@@ -103,7 +103,7 @@ fn drop(&mut self) {
 
 impl<'gpu> Pramin<'gpu> {
     /// Alignment required by the PRAMIN window.
-    const BASE_ALIGN: Alignment = Alignment::new::<SZ_64K>();
+    const BASE_ALIGN: Alignment = Alignment::SZ_64K;
 
     /// Creates the window manager for the given VRAM region.
     pub(super) fn new(
diff --git a/drivers/gpu/nova-core/vbios.rs b/drivers/gpu/nova-core/vbios.rs
index 9c214b9f4dd9..a2d2d170b501 100644
--- a/drivers/gpu/nova-core/vbios.rs
+++ b/drivers/gpu/nova-core/vbios.rs
@@ -11,7 +11,10 @@
         Alignment, //
     },
     register,
-    sizes::SZ_4K,
+    sizes::{
+        SizeConstants,
+        SZ_4K, //
+    },
     sync::aref::ARef,
 };
 
@@ -291,7 +294,7 @@ fn next(&mut self) -> Option<Self::Item> {
 
         // Advance to next image (aligned to 512 bytes).
         self.current_offset += image_size;
-        self.current_offset = self.current_offset.align_up(Alignment::new::<512>())?;
+        self.current_offset = self.current_offset.align_up(Alignment::SZ_512)?;
 
         Some(Ok(full_image))
     }

-- 
2.56.0


^ permalink raw reply	[flat|nested] 13+ messages in thread

* [PATCH v11 4/5] rust: id_pool: do not round capacity up to BitmapVec::MAX_INLINE_LEN
  2026-11-09  8:32 [PATCH v11 0/5] rust: Add support for reserving of ranges of IDs Eliot Courtney
                   ` (2 preceding siblings ...)
  2026-11-09  8:32 ` [PATCH v11 3/5] gpu: nova-core: " Eliot Courtney
@ 2026-11-09  8:32 ` Eliot Courtney
  2026-11-09 12:08   ` Alexandre Courbot
  2026-11-09 12:36   ` Gary Guo
  2026-11-09  8:32 ` [PATCH v11 5/5] gpu: nova-core: add ChannelIdPool Eliot Courtney
                   ` (2 subsequent siblings)
  6 siblings, 2 replies; 13+ messages in thread
From: Eliot Courtney @ 2026-11-09  8:32 UTC (permalink / raw)
  To: Alice Ryhl, Burak Emir, Yury Norov, Miguel Ojeda, Boqun Feng,
	Gary Guo, Björn Roy Baron, Benno Lossin, Andreas Hindborg,
	Trevor Gross, Danilo Krummrich, Daniel Almeida, Tamir Duberstein,
	Alexandre Courbot, Onur Özkan, David Airlie, Simona Vetter
  Cc: Greg Kroah-Hartman, John Hubbard, Alistair Popple, Timur Tabi,
	Zhi Wang, rust-for-linux, linux-kernel, nova-gpu, dri-devel,
	Eliot Courtney

Current code in IdPool::with_capacity rounds the capacity up to
BitmapVec::MAX_INLINE_LEN, but BitmapVec::new works fine with values
smaller than this and still uses an inline representation. Remove this
behaviour.

This allows specifying a real capacity of 0, which was not previously
possible. This breaks `grow_request` in this case, so change it to grow
to at least `BitmapVec::MAX_INLINE_LEN`, mirroring the capacity floor in
`shrink_request`.

Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Burak Emir <burak.emir@gmail.com>
Signed-off-by: Eliot Courtney <ecourtney@nvidia.com>
---
 rust/kernel/id_pool.rs | 38 ++++++++++++++++++++++++++++++++------
 1 file changed, 32 insertions(+), 6 deletions(-)

diff --git a/rust/kernel/id_pool.rs b/rust/kernel/id_pool.rs
index 92eeb7caa243..f77bd90325ff 100644
--- a/rust/kernel/id_pool.rs
+++ b/rust/kernel/id_pool.rs
@@ -112,13 +112,8 @@ pub fn new() -> Self {
     }
 
     /// Constructs a new [`IdPool`] with space for a specific number of bits.
-    ///
-    /// A capacity below [`MAX_INLINE_LEN`] is adjusted to [`MAX_INLINE_LEN`].
-    ///
-    /// [`MAX_INLINE_LEN`]: BitmapVec::MAX_INLINE_LEN
     #[inline]
     pub fn with_capacity(num_ids: usize, flags: Flags) -> Result<Self, AllocError> {
-        let num_ids = usize::max(num_ids, BitmapVec::MAX_INLINE_LEN);
         let map = BitmapVec::new(num_ids, flags)?;
         Ok(Self { map })
     }
@@ -152,6 +147,13 @@ pub fn capacity(&self) -> usize {
     /// let resizer = alloc_request.realloc(GFP_KERNEL)?;
     /// pool.shrink(resizer);
     /// assert_eq!(pool.capacity(), BitmapVec::MAX_INLINE_LEN);
+    ///
+    /// // A pool at the `MAX_INLINE_LEN` floor cannot shrink further.
+    /// assert!(pool.shrink_request().is_none());
+    ///
+    /// // Neither can a pool with a capacity below `MAX_INLINE_LEN`.
+    /// let small = IdPool::with_capacity(8, GFP_KERNEL)?;
+    /// assert!(small.shrink_request().is_none());
     /// # Ok::<(), AllocError>(())
     /// ```
     #[inline]
@@ -198,12 +200,36 @@ pub fn shrink(&mut self, mut resizer: PoolResizer) {
 
     /// Returns a [`ReallocRequest`] for growing this [`IdPool`], if possible.
     ///
+    /// Grows to at least [`MAX_INLINE_LEN`].
     /// The capacity of an [`IdPool`] cannot be grown above [`MAX_LEN`].
     ///
+    /// [`MAX_INLINE_LEN`]: BitmapVec::MAX_INLINE_LEN
     /// [`MAX_LEN`]: BitmapVec::MAX_LEN
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use kernel::{
+    ///     alloc::AllocError,
+    ///     bitmap::BitmapVec,
+    ///     id_pool::IdPool, //
+    /// };
+    ///
+    /// // Grow goes to at least BitmapVec::MAX_INLINE_LEN.
+    /// let mut pool = IdPool::with_capacity(1, GFP_KERNEL)?;
+    /// let resizer = pool.grow_request().ok_or(AllocError)?.realloc(GFP_KERNEL)?;
+    /// pool.grow(resizer);
+    /// assert_eq!(pool.capacity(), BitmapVec::MAX_INLINE_LEN);
+    ///
+    /// // Grow doubles if at least BitmapVec::MAX_INLINE_LEN.
+    /// let resizer = pool.grow_request().ok_or(AllocError)?.realloc(GFP_KERNEL)?;
+    /// pool.grow(resizer);
+    /// assert_eq!(pool.capacity(), 2 * BitmapVec::MAX_INLINE_LEN);
+    /// # Ok::<(), AllocError>(())
+    /// ```
     #[inline]
     pub fn grow_request(&self) -> Option<ReallocRequest> {
-        let num_ids = self.capacity() * 2;
+        let num_ids = usize::max(BitmapVec::MAX_INLINE_LEN, self.capacity() * 2);
         if num_ids > BitmapVec::MAX_LEN {
             return None;
         }

-- 
2.56.0


^ permalink raw reply	[flat|nested] 13+ messages in thread

* [PATCH v11 5/5] gpu: nova-core: add ChannelIdPool
  2026-11-09  8:32 [PATCH v11 0/5] rust: Add support for reserving of ranges of IDs Eliot Courtney
                   ` (3 preceding siblings ...)
  2026-11-09  8:32 ` [PATCH v11 4/5] rust: id_pool: do not round capacity up to BitmapVec::MAX_INLINE_LEN Eliot Courtney
@ 2026-11-09  8:32 ` Eliot Courtney
  2026-11-09 21:21 ` (subset) [PATCH v11 0/5] rust: Add support for reserving of ranges of IDs Danilo Krummrich
  2026-11-09 21:33 ` Danilo Krummrich
  6 siblings, 0 replies; 13+ messages in thread
From: Eliot Courtney @ 2026-11-09  8:32 UTC (permalink / raw)
  To: Alice Ryhl, Burak Emir, Yury Norov, Miguel Ojeda, Boqun Feng,
	Gary Guo, Björn Roy Baron, Benno Lossin, Andreas Hindborg,
	Trevor Gross, Danilo Krummrich, Daniel Almeida, Tamir Duberstein,
	Alexandre Courbot, Onur Özkan, David Airlie, Simona Vetter
  Cc: Greg Kroah-Hartman, John Hubbard, Alistair Popple, Timur Tabi,
	Zhi Wang, rust-for-linux, linux-kernel, nova-gpu, dri-devel,
	Eliot Courtney

Add `ChannelIdPool` which adds automatic tracking and releasing of
channel IDs on top of `IdPool`. This is necessary for apportioning
ranges of channel IDs to be used in e.g. vGPU.

Channel IDs are allocated as a contiguous sequence with a specific
length and sometimes a specific alignment [1] for vGPU. The ID space is
small (limited to 2048) and allocation is not on a hot path, so a
bitmap-backed `IdPool` is a better fit than IDA/xarray (which allocate a
single ID within a range, not a contiguous sequence) or a maple tree
(where aligned allocation needs an alloc_range()+erase() retry loop that
essentially reimplements bitmap_find_next_zero_area()) [2]. It is
also faster than maple tree [3].

Link: https://lore.kernel.org/all/84bc8bd2-e292-4b84-9580-a1b5df4c5bdc@nvidia.com/ # [1]
Link: https://lore.kernel.org/all/20260710-chid-maple-v1-1-4ee869055268@nvidia.com/ # [2]
Link: https://lore.kernel.org/all/20260717053241.916441-1-ynorov@nvidia.com/ # [3]
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Eliot Courtney <ecourtney@nvidia.com>
---
 drivers/gpu/nova-core/gpu.rs         |   2 +
 drivers/gpu/nova-core/gpu/channel.rs | 198 +++++++++++++++++++++++++++++++++++
 2 files changed, 200 insertions(+)

diff --git a/drivers/gpu/nova-core/gpu.rs b/drivers/gpu/nova-core/gpu.rs
index d185e927233f..90b1d24cdf00 100644
--- a/drivers/gpu/nova-core/gpu.rs
+++ b/drivers/gpu/nova-core/gpu.rs
@@ -53,6 +53,8 @@
     vgpu::VgpuManager, //
 };
 
+#[cfg_attr(not(CONFIG_KUNIT = "y"), expect(dead_code))]
+mod channel;
 mod hal;
 mod regs;
 
diff --git a/drivers/gpu/nova-core/gpu/channel.rs b/drivers/gpu/nova-core/gpu/channel.rs
new file mode 100644
index 000000000000..485efaba059d
--- /dev/null
+++ b/drivers/gpu/nova-core/gpu/channel.rs
@@ -0,0 +1,198 @@
+// SPDX-License-Identifier: GPL-2.0
+// SPDX-FileCopyrightText: Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+
+//! Channel ID allocation.
+
+use core::{
+    num::NonZero,
+    ops::{
+        Deref,
+        Range, //
+    }, //
+};
+
+use kernel::{
+    id_pool::IdPool,
+    prelude::*,
+    ptr::Alignment,
+    sync::{
+        new_mutex,
+        Mutex, //
+    }, //
+};
+
+/// Pool for tracking reservations of channel IDs.
+#[pin_data]
+pub(crate) struct ChannelIdPool {
+    #[pin]
+    inner: Mutex<IdPool>,
+}
+
+impl ChannelIdPool {
+    /// Creates a pool managing `num_chids` channel IDs.
+    pub(crate) fn new(num_chids: NonZero<usize>) -> impl PinInit<Self, Error> {
+        try_pin_init!(Self {
+            inner <- new_mutex!(IdPool::with_capacity(num_chids.get(), GFP_KERNEL)?),
+        })
+    }
+
+    /// Reserves a contiguous area of `count` channel IDs starting at a multiple of `align`,
+    /// returning a guard that releases the area on drop.
+    pub(crate) fn reserve_ids(
+        &self,
+        count: NonZero<usize>,
+        align: Alignment,
+    ) -> Result<ChannelIdReservation<'_>> {
+        let mut ids = self.inner.lock();
+        let range = ids.reserve_ids(0, count, align).ok_or(ENOSPC)?;
+        Ok(ChannelIdReservation { pool: self, range })
+    }
+}
+
+/// A reserved contiguous area of channel IDs.
+///
+/// Releases the whole area back to its [`ChannelIdPool`] when dropped. Releasing locks a
+/// sleeping [`Mutex`], so the area must be dropped in a context that is allowed to sleep.
+#[must_use = "the channel ID reservation is released immediately when unused"]
+pub(crate) struct ChannelIdReservation<'a> {
+    pool: &'a ChannelIdPool,
+    range: Range<usize>,
+}
+
+impl Drop for ChannelIdReservation<'_> {
+    fn drop(&mut self) {
+        self.pool.inner.lock().release_ids(&self.range);
+    }
+}
+
+impl Deref for ChannelIdReservation<'_> {
+    type Target = Range<usize>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.range
+    }
+}
+
+#[kunit_tests(nova_core_channel)]
+mod tests {
+    use super::*;
+    use kernel::sizes::SizeConstants;
+
+    #[test]
+    fn chid_reservation() -> Result {
+        let pool = KBox::pin_init(ChannelIdPool::new(cv!(2048)), GFP_KERNEL)?;
+
+        let first = pool.reserve_ids(cv!(48), Alignment::SZ_1)?;
+        assert_eq!(0, first.start);
+        assert_eq!(48, first.len());
+        assert_eq!(48, first.end);
+
+        let second = pool.reserve_ids(cv!(48), Alignment::SZ_1)?;
+        assert!(first.end <= second.start || second.end <= first.start);
+
+        let first_start = first.start;
+        drop(first);
+        assert_eq!(
+            first_start,
+            pool.reserve_ids(cv!(48), Alignment::SZ_1)?.start
+        );
+        Ok(())
+    }
+
+    #[test]
+    fn chid_reservation_drop() -> Result {
+        let pool = KBox::pin_init(ChannelIdPool::new(cv!(8)), GFP_KERNEL)?;
+
+        let a = pool.reserve_ids(cv!(3), Alignment::SZ_1)?;
+        let b = pool.reserve_ids(cv!(3), Alignment::SZ_1)?;
+        let c = pool.reserve_ids(cv!(2), Alignment::SZ_1)?;
+        assert_eq!(0, a.start);
+        assert_eq!(3, b.start);
+        assert_eq!(6, c.start);
+
+        drop(b);
+
+        // Only have space for 3 IDs right now.
+        assert_eq!(
+            Err(ENOSPC),
+            pool.reserve_ids(cv!(4), Alignment::SZ_1).map(|_| ())
+        );
+        let b = pool.reserve_ids(cv!(3), Alignment::SZ_1)?;
+        assert_eq!(3, b.start);
+
+        drop(a);
+        drop(c);
+        drop(b);
+
+        // Everything was dropped so the pool should be empty.
+        assert_eq!(0, pool.reserve_ids(cv!(8), Alignment::SZ_1)?.start);
+        Ok(())
+    }
+
+    #[test]
+    fn chid_bounded_by_num_chids() -> Result {
+        let pool = KBox::pin_init(ChannelIdPool::new(cv!(4)), GFP_KERNEL)?;
+
+        {
+            let a = pool.reserve_ids(cv!(1), Alignment::SZ_1)?;
+            let b = pool.reserve_ids(cv!(1), Alignment::SZ_1)?;
+            let c = pool.reserve_ids(cv!(1), Alignment::SZ_1)?;
+            let d = pool.reserve_ids(cv!(1), Alignment::SZ_1)?;
+            assert_eq!(0, a.start);
+            assert_eq!(1, b.start);
+            assert_eq!(2, c.start);
+            assert_eq!(3, d.start);
+            assert_eq!(
+                Err(ENOSPC),
+                pool.reserve_ids(cv!(1), Alignment::SZ_1).map(|_| ())
+            );
+        }
+
+        assert_eq!(0, pool.reserve_ids(cv!(4), Alignment::SZ_1)?.start);
+        assert_eq!(
+            Err(ENOSPC),
+            pool.reserve_ids(cv!(5), Alignment::SZ_1).map(|_| ())
+        );
+
+        let head = pool.reserve_ids(cv!(3), Alignment::SZ_1)?;
+        assert_eq!(0, head.start);
+        assert_eq!(
+            Err(ENOSPC),
+            pool.reserve_ids(cv!(2), Alignment::SZ_1).map(|_| ())
+        );
+        assert_eq!(3, pool.reserve_ids(cv!(1), Alignment::SZ_1)?.start);
+        Ok(())
+    }
+
+    #[test]
+    fn chid_reservation_aligned() -> Result {
+        let pool = KBox::pin_init(ChannelIdPool::new(cv!(16)), GFP_KERNEL)?;
+
+        // Alloc 0 so the first fit for the next area is unaligned.
+        let pad = pool.reserve_ids(cv!(1), Alignment::SZ_1)?;
+        assert_eq!(0, pad.start);
+
+        let a = pool.reserve_ids(cv!(4), Alignment::SZ_4)?;
+        assert_eq!(4, a.start);
+
+        // The area skipped over by the aligned allocation should still be available.
+        let b = pool.reserve_ids(cv!(1), Alignment::SZ_1)?;
+        assert_eq!(1, b.start);
+
+        let c = pool.reserve_ids(cv!(8), Alignment::SZ_8)?;
+        assert_eq!(8, c.start);
+
+        // Only 2 IDs left.
+        assert_eq!(
+            Err(ENOSPC),
+            pool.reserve_ids(cv!(4), Alignment::SZ_4).map(|_| ())
+        );
+        assert_eq!(
+            Err(ENOSPC),
+            pool.reserve_ids(cv!(1), Alignment::SZ_32).map(|_| ())
+        );
+
+        assert_eq!(2, pool.reserve_ids(cv!(2), Alignment::SZ_1)?.start);
+        Ok(())
+    }
+}

-- 
2.56.0


^ permalink raw reply	[flat|nested] 13+ messages in thread

* Re: [PATCH v11 4/5] rust: id_pool: do not round capacity up to BitmapVec::MAX_INLINE_LEN
  2026-11-09  8:32 ` [PATCH v11 4/5] rust: id_pool: do not round capacity up to BitmapVec::MAX_INLINE_LEN Eliot Courtney
@ 2026-11-09 12:08   ` Alexandre Courbot
  2026-11-09 12:36   ` Gary Guo
  1 sibling, 0 replies; 13+ messages in thread
From: Alexandre Courbot @ 2026-11-09 12:08 UTC (permalink / raw)
  To: Eliot Courtney
  Cc: Alice Ryhl, Burak Emir, Yury Norov, Miguel Ojeda, Boqun Feng,
	Gary Guo, Björn Roy Baron, Benno Lossin, Andreas Hindborg,
	Trevor Gross, Danilo Krummrich, Daniel Almeida, Tamir Duberstein,
	Onur Özkan, David Airlie, Simona Vetter, Greg Kroah-Hartman,
	John Hubbard, Alistair Popple, Timur Tabi, Zhi Wang,
	rust-for-linux, linux-kernel, nova-gpu, dri-devel

On Mon Nov 9, 2026 at 5:32 PM JST, Eliot Courtney wrote:
> Current code in IdPool::with_capacity rounds the capacity up to
> BitmapVec::MAX_INLINE_LEN, but BitmapVec::new works fine with values
> smaller than this and still uses an inline representation. Remove this
> behaviour.
>
> This allows specifying a real capacity of 0, which was not previously
> possible. This breaks `grow_request` in this case, so change it to grow
> to at least `BitmapVec::MAX_INLINE_LEN`, mirroring the capacity floor in
> `shrink_request`.
>
> Reviewed-by: Alice Ryhl <aliceryhl@google.com>
> Reviewed-by: Burak Emir <burak.emir@gmail.com>
> Signed-off-by: Eliot Courtney <ecourtney@nvidia.com>

Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>

^ permalink raw reply	[flat|nested] 13+ messages in thread

* Re: [PATCH v11 4/5] rust: id_pool: do not round capacity up to BitmapVec::MAX_INLINE_LEN
  2026-11-09  8:32 ` [PATCH v11 4/5] rust: id_pool: do not round capacity up to BitmapVec::MAX_INLINE_LEN Eliot Courtney
  2026-11-09 12:08   ` Alexandre Courbot
@ 2026-11-09 12:36   ` Gary Guo
  1 sibling, 0 replies; 13+ messages in thread
From: Gary Guo @ 2026-11-09 12:36 UTC (permalink / raw)
  To: Eliot Courtney, Alice Ryhl, Burak Emir, Yury Norov, Miguel Ojeda,
	Boqun Feng, Gary Guo, Björn Roy Baron, Benno Lossin,
	Andreas Hindborg, Trevor Gross, Danilo Krummrich, Daniel Almeida,
	Tamir Duberstein, Alexandre Courbot, Onur Özkan,
	David Airlie, Simona Vetter
  Cc: Greg Kroah-Hartman, John Hubbard, Alistair Popple, Timur Tabi,
	Zhi Wang, rust-for-linux, linux-kernel, nova-gpu, dri-devel

On Mon Nov 9, 2026 at 8:32 AM GMT, Eliot Courtney wrote:
> Current code in IdPool::with_capacity rounds the capacity up to
> BitmapVec::MAX_INLINE_LEN, but BitmapVec::new works fine with values
> smaller than this and still uses an inline representation. Remove this
> behaviour.
>
> This allows specifying a real capacity of 0, which was not previously
> possible. This breaks `grow_request` in this case, so change it to grow
> to at least `BitmapVec::MAX_INLINE_LEN`, mirroring the capacity floor in
> `shrink_request`.
>
> Reviewed-by: Alice Ryhl <aliceryhl@google.com>
> Reviewed-by: Burak Emir <burak.emir@gmail.com>
> Signed-off-by: Eliot Courtney <ecourtney@nvidia.com>
> ---
>  rust/kernel/id_pool.rs | 38 ++++++++++++++++++++++++++++++++------
>  1 file changed, 32 insertions(+), 6 deletions(-)
>
> diff --git a/rust/kernel/id_pool.rs b/rust/kernel/id_pool.rs
> index 92eeb7caa243..f77bd90325ff 100644
> --- a/rust/kernel/id_pool.rs
> +++ b/rust/kernel/id_pool.rs
> @@ -112,13 +112,8 @@ pub fn new() -> Self {
>      }
>  
>      /// Constructs a new [`IdPool`] with space for a specific number of bits.
> -    ///
> -    /// A capacity below [`MAX_INLINE_LEN`] is adjusted to [`MAX_INLINE_LEN`].
> -    ///
> -    /// [`MAX_INLINE_LEN`]: BitmapVec::MAX_INLINE_LEN
>      #[inline]
>      pub fn with_capacity(num_ids: usize, flags: Flags) -> Result<Self, AllocError> {
> -        let num_ids = usize::max(num_ids, BitmapVec::MAX_INLINE_LEN);
>          let map = BitmapVec::new(num_ids, flags)?;
>          Ok(Self { map })
>      }
> @@ -152,6 +147,13 @@ pub fn capacity(&self) -> usize {
>      /// let resizer = alloc_request.realloc(GFP_KERNEL)?;
>      /// pool.shrink(resizer);
>      /// assert_eq!(pool.capacity(), BitmapVec::MAX_INLINE_LEN);
> +    ///
> +    /// // A pool at the `MAX_INLINE_LEN` floor cannot shrink further.
> +    /// assert!(pool.shrink_request().is_none());
> +    ///
> +    /// // Neither can a pool with a capacity below `MAX_INLINE_LEN`.
> +    /// let small = IdPool::with_capacity(8, GFP_KERNEL)?;
> +    /// assert!(small.shrink_request().is_none());
>      /// # Ok::<(), AllocError>(())
>      /// ```
>      #[inline]
> @@ -198,12 +200,36 @@ pub fn shrink(&mut self, mut resizer: PoolResizer) {
>  
>      /// Returns a [`ReallocRequest`] for growing this [`IdPool`], if possible.
>      ///
> +    /// Grows to at least [`MAX_INLINE_LEN`].
>      /// The capacity of an [`IdPool`] cannot be grown above [`MAX_LEN`].
>      ///
> +    /// [`MAX_INLINE_LEN`]: BitmapVec::MAX_INLINE_LEN
>      /// [`MAX_LEN`]: BitmapVec::MAX_LEN
> +    ///
> +    /// # Examples
> +    ///
> +    /// ```
> +    /// use kernel::{
> +    ///     alloc::AllocError,
> +    ///     bitmap::BitmapVec,
> +    ///     id_pool::IdPool, //
> +    /// };
> +    ///
> +    /// // Grow goes to at least BitmapVec::MAX_INLINE_LEN.
> +    /// let mut pool = IdPool::with_capacity(1, GFP_KERNEL)?;
> +    /// let resizer = pool.grow_request().ok_or(AllocError)?.realloc(GFP_KERNEL)?;
> +    /// pool.grow(resizer);
> +    /// assert_eq!(pool.capacity(), BitmapVec::MAX_INLINE_LEN);
> +    ///
> +    /// // Grow doubles if at least BitmapVec::MAX_INLINE_LEN.
> +    /// let resizer = pool.grow_request().ok_or(AllocError)?.realloc(GFP_KERNEL)?;
> +    /// pool.grow(resizer);
> +    /// assert_eq!(pool.capacity(), 2 * BitmapVec::MAX_INLINE_LEN);
> +    /// # Ok::<(), AllocError>(())
> +    /// ```
>      #[inline]
>      pub fn grow_request(&self) -> Option<ReallocRequest> {
> -        let num_ids = self.capacity() * 2;
> +        let num_ids = usize::max(BitmapVec::MAX_INLINE_LEN, self.capacity() * 2);

It looks like your want the `IdPool` have a controlled capacity. However, as
soon as `grow_request` is used, the capacity becomes uncontrolled.

It feels that this actually means that there are two use cases here: unbounded
IdPool (where capacity just means the _current_ capacity) and bounded IdPool
(where capacity means the _max_ capacity).

This is more similar to a difference between `len()` and `capacity()`. It feels
to me that you're merrging `Vec<bool>` and `Box<[bool]>` into a single type
where it shouldn't.

Best,
Gary


^ permalink raw reply	[flat|nested] 13+ messages in thread

* Re: [PATCH v11 1/5] rust: io: use Alignment size constants
  2026-11-09  8:32 ` [PATCH v11 1/5] rust: io: use Alignment size constants Eliot Courtney
@ 2026-11-09 12:37   ` Gary Guo
  0 siblings, 0 replies; 13+ messages in thread
From: Gary Guo @ 2026-11-09 12:37 UTC (permalink / raw)
  To: Eliot Courtney, Alice Ryhl, Burak Emir, Yury Norov, Miguel Ojeda,
	Boqun Feng, Gary Guo, Björn Roy Baron, Benno Lossin,
	Andreas Hindborg, Trevor Gross, Danilo Krummrich, Daniel Almeida,
	Tamir Duberstein, Alexandre Courbot, Onur Özkan,
	David Airlie, Simona Vetter
  Cc: Greg Kroah-Hartman, John Hubbard, Alistair Popple, Timur Tabi,
	Zhi Wang, rust-for-linux, linux-kernel, nova-gpu, dri-devel

On Mon Nov 9, 2026 at 8:32 AM GMT, Eliot Courtney wrote:
> Use `SizeConstants` for Alignment that are implemented now.
> 
> Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
> Reviewed-by: Alice Ryhl <aliceryhl@google.com>
> Signed-off-by: Eliot Courtney <ecourtney@nvidia.com>

Reviewed-by: Gary Guo <gary@garyguo.net>

> ---
>  rust/kernel/io.rs | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)


^ permalink raw reply	[flat|nested] 13+ messages in thread

* Re: [PATCH v11 2/5] rust: gpu: buddy: use Alignment size constants
  2026-11-09  8:32 ` [PATCH v11 2/5] rust: gpu: buddy: " Eliot Courtney
@ 2026-11-09 12:37   ` Gary Guo
  0 siblings, 0 replies; 13+ messages in thread
From: Gary Guo @ 2026-11-09 12:37 UTC (permalink / raw)
  To: Eliot Courtney, Alice Ryhl, Burak Emir, Yury Norov, Miguel Ojeda,
	Boqun Feng, Gary Guo, Björn Roy Baron, Benno Lossin,
	Andreas Hindborg, Trevor Gross, Danilo Krummrich, Daniel Almeida,
	Tamir Duberstein, Alexandre Courbot, Onur Özkan,
	David Airlie, Simona Vetter
  Cc: Greg Kroah-Hartman, John Hubbard, Alistair Popple, Timur Tabi,
	Zhi Wang, rust-for-linux, linux-kernel, nova-gpu, dri-devel

On Mon Nov 9, 2026 at 8:32 AM GMT, Eliot Courtney wrote:
> Use `SizeConstants` for Alignment that are implemented now.
> 
> Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
> Reviewed-by: Alice Ryhl <aliceryhl@google.com>
> Signed-off-by: Eliot Courtney <ecourtney@nvidia.com>

Reviewed-by: Gary Guo <gary@garyguo.net>

> ---
>  rust/kernel/gpu/buddy.rs | 26 +++++++++++++-------------
>  1 file changed, 13 insertions(+), 13 deletions(-)


^ permalink raw reply	[flat|nested] 13+ messages in thread

* Re: [PATCH v11 3/5] gpu: nova-core: use Alignment size constants
  2026-11-09  8:32 ` [PATCH v11 3/5] gpu: nova-core: " Eliot Courtney
@ 2026-11-09 12:37   ` Gary Guo
  0 siblings, 0 replies; 13+ messages in thread
From: Gary Guo @ 2026-11-09 12:37 UTC (permalink / raw)
  To: Eliot Courtney, Alice Ryhl, Burak Emir, Yury Norov, Miguel Ojeda,
	Boqun Feng, Gary Guo, Björn Roy Baron, Benno Lossin,
	Andreas Hindborg, Trevor Gross, Danilo Krummrich, Daniel Almeida,
	Tamir Duberstein, Alexandre Courbot, Onur Özkan,
	David Airlie, Simona Vetter
  Cc: Greg Kroah-Hartman, John Hubbard, Alistair Popple, Timur Tabi,
	Zhi Wang, rust-for-linux, linux-kernel, nova-gpu, dri-devel

On Mon Nov 9, 2026 at 8:32 AM GMT, Eliot Courtney wrote:
> Use `SizeConstants` for Alignment that are implemented now.
> 
> Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
> Reviewed-by: Alice Ryhl <aliceryhl@google.com>
> Signed-off-by: Eliot Courtney <ecourtney@nvidia.com>

Reviewed-by: Gary Guo <gary@garyguo.net>

> ---
>  drivers/gpu/nova-core/fb.rs               | 10 +++++-----
>  drivers/gpu/nova-core/fb/hal/gb100.rs     |  2 +-
>  drivers/gpu/nova-core/fsp.rs              |  4 ++--
>  drivers/gpu/nova-core/gpu.rs              |  7 ++-----
>  drivers/gpu/nova-core/gsp/fw.rs           | 12 +++---------
>  drivers/gpu/nova-core/mm.rs               |  2 +-
>  drivers/gpu/nova-core/mm/bar_user.rs      |  7 ++++---
>  drivers/gpu/nova-core/mm/pagetable/map.rs |  7 +++++--
>  drivers/gpu/nova-core/mm/pramin.rs        |  6 +++---
>  drivers/gpu/nova-core/vbios.rs            |  7 +++++--
>  10 files changed, 31 insertions(+), 33 deletions(-)


^ permalink raw reply	[flat|nested] 13+ messages in thread

* Re: (subset) [PATCH v11 0/5] rust: Add support for reserving of ranges of IDs
  2026-11-09  8:32 [PATCH v11 0/5] rust: Add support for reserving of ranges of IDs Eliot Courtney
                   ` (4 preceding siblings ...)
  2026-11-09  8:32 ` [PATCH v11 5/5] gpu: nova-core: add ChannelIdPool Eliot Courtney
@ 2026-11-09 21:21 ` Danilo Krummrich
  2026-11-09 21:33 ` Danilo Krummrich
  6 siblings, 0 replies; 13+ messages in thread
From: Danilo Krummrich @ 2026-11-09 21:21 UTC (permalink / raw)
  To: Eliot Courtney
  Cc: Alice Ryhl, Burak Emir, Yury Norov, Miguel Ojeda, Boqun Feng,
	Gary Guo, Björn Roy Baron, Benno Lossin, Andreas Hindborg,
	Trevor Gross, Danilo Krummrich, Daniel Almeida, Tamir Duberstein,
	Alexandre Courbot, Onur Özkan, David Airlie, Simona Vetter,
	Greg Kroah-Hartman, John Hubbard, Alistair Popple, Timur Tabi,
	Zhi Wang, rust-for-linux, linux-kernel, nova-gpu, dri-devel

On Mon, 09 Nov 2026 17:32:48 +0900, Eliot Courtney wrote:
> [PATCH v11 0/5] rust: Add support for reserving of ranges of IDs

Applied, thanks!

  Branch: driver-core-testing
  Tree:   git://git.kernel.org/pub/scm/linux/kernel/git/driver-core/driver-core.git

[1/5] rust: io: use Alignment size constants
      commit: 4d1f2b176df7

The patch will appear in the next linux-next integration (typically within 24
hours on weekdays).

The patch is in the driver-core-testing branch and will be promoted to
driver-core-next after validation.

^ permalink raw reply	[flat|nested] 13+ messages in thread

* Re: (subset) [PATCH v11 0/5] rust: Add support for reserving of ranges of IDs
  2026-11-09  8:32 [PATCH v11 0/5] rust: Add support for reserving of ranges of IDs Eliot Courtney
                   ` (5 preceding siblings ...)
  2026-11-09 21:21 ` (subset) [PATCH v11 0/5] rust: Add support for reserving of ranges of IDs Danilo Krummrich
@ 2026-11-09 21:33 ` Danilo Krummrich
  6 siblings, 0 replies; 13+ messages in thread
From: Danilo Krummrich @ 2026-11-09 21:33 UTC (permalink / raw)
  To: Eliot Courtney
  Cc: Alice Ryhl, Burak Emir, Yury Norov, Miguel Ojeda, Boqun Feng,
	Gary Guo, Björn Roy Baron, Benno Lossin, Andreas Hindborg,
	Trevor Gross, Danilo Krummrich, Daniel Almeida, Tamir Duberstein,
	Alexandre Courbot, Onur Özkan, David Airlie, Simona Vetter,
	Greg Kroah-Hartman, John Hubbard, Alistair Popple, Timur Tabi,
	Zhi Wang, rust-for-linux, linux-kernel, nova-gpu, dri-devel

On Mon, 09 Nov 2026 17:32:48 +0900, Eliot Courtney wrote:
> [PATCH v11 0/5] rust: Add support for reserving of ranges of IDs

Applied, thanks!

  Branch: drm-rust-next
  Tree:   https://gitlab.freedesktop.org/drm/rust/kernel.git

[2/5] rust: gpu: buddy: use Alignment size constants
      commit: 1937c07c9f83
[3/5] gpu: nova-core: use Alignment size constants
      commit: a7cdb17ca0d7

The patches will appear in the next linux-next integration (typically within 24
hours on weekdays).

The patches are queued up for the upcoming merge window for the next major
kernel release.

^ permalink raw reply	[flat|nested] 13+ messages in thread

end of thread, other threads:[~2026-11-09 21:33 UTC | newest]

Thread overview: 13+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2026-11-09  8:32 [PATCH v11 0/5] rust: Add support for reserving of ranges of IDs Eliot Courtney
2026-11-09  8:32 ` [PATCH v11 1/5] rust: io: use Alignment size constants Eliot Courtney
2026-11-09 12:37   ` Gary Guo
2026-11-09  8:32 ` [PATCH v11 2/5] rust: gpu: buddy: " Eliot Courtney
2026-11-09 12:37   ` Gary Guo
2026-11-09  8:32 ` [PATCH v11 3/5] gpu: nova-core: " Eliot Courtney
2026-11-09 12:37   ` Gary Guo
2026-11-09  8:32 ` [PATCH v11 4/5] rust: id_pool: do not round capacity up to BitmapVec::MAX_INLINE_LEN Eliot Courtney
2026-11-09 12:08   ` Alexandre Courbot
2026-11-09 12:36   ` Gary Guo
2026-11-09  8:32 ` [PATCH v11 5/5] gpu: nova-core: add ChannelIdPool Eliot Courtney
2026-11-09 21:21 ` (subset) [PATCH v11 0/5] rust: Add support for reserving of ranges of IDs Danilo Krummrich
2026-11-09 21:33 ` Danilo Krummrich

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