These properties are very useful to have (and to be used by nova-core)
and should be accessible.
Signed-off-by: Alexandre Courbot <acour...@nvidia.com>
---
rust/kernel/dma.rs | 32 ++++++++++++++++++++++++++------
1 file changed, 26 insertions(+), 6 deletions(-)
diff --git a/rust/kernel/dma.rs b/rust/kernel/dma.rs
index
a33261c62e0c2d3c2c9e92a4c058faab594e5355..1a6fc800256500ae04099fbf4f9a1bd1115ce202
100644
--- a/rust/kernel/dma.rs
+++ b/rust/kernel/dma.rs
@@ -114,9 +114,11 @@ pub mod attrs {
///
/// # Invariants
///
-/// For the lifetime of an instance of [`CoherentAllocation`], the `cpu_addr`
is a valid pointer
-/// to an allocated region of consistent memory and `dma_handle` is the DMA
address base of
-/// the region.
+/// - For the lifetime of an instance of [`CoherentAllocation`], the
`cpu_addr` is a valid pointer
+/// to an allocated region of consistent memory and `dma_handle` is the DMA
address base of the
+/// region.
+/// - The size in bytes of the allocation is equal to `size_of::<T> * count`.
+/// - `size_of::<T> * count` fits into a `usize`.
// TODO
//
// DMA allocations potentially carry device resources (e.g.IOMMU mappings),
hence for soundness
@@ -179,9 +181,12 @@ pub fn alloc_attrs(
if ret.is_null() {
return Err(ENOMEM);
}
- // INVARIANT: We just successfully allocated a coherent region which
is accessible for
- // `count` elements, hence the cpu address is valid. We also hold a
refcounted reference
- // to the device.
+ // INVARIANT:
+ // - We just successfully allocated a coherent region which is
accessible for
+ // `count` elements, hence the cpu address is valid. We also hold a
refcounted reference
+ // to the device.
+ // - The allocated `size` is equal to `size_of::<T> * count`.
+ // - The allocated `size` fits into a `usize`.
Ok(Self {
dev: dev.into(),
dma_handle,
@@ -201,6 +206,21 @@ pub fn alloc_coherent(
CoherentAllocation::alloc_attrs(dev, count, gfp_flags, Attrs(0))
}
+ /// Returns the number of elements `T` in this allocation.
+ ///
+ /// Note that this is not the size of the allocation in bytes, which is
provided by
+ /// [`Self::size`].
+ pub fn count(&self) -> usize {
+ self.count
+ }
+
+ /// Returns the size in bytes of this allocation.
+ pub fn size(&self) -> usize {
+ // INVARIANT: The type invariant of `Self` guarantees that
size_of::<T> * count` fits into
+ // a `usize`.
+ self.count * core::mem::size_of::<T>()
+ }
+
/// Returns the base address to the allocated region in the CPU's virtual
address space.
pub fn start_ptr(&self) -> *const T {
self.cpu_addr
--
2.49.0
