[PATCH] rust: pci: add resource_flags accessor
From: Eliot Courtney <hidden>
Date: 2026-09-08 07:51:57
Also in:
driver-core, lkml, nova-gpu
Subsystem:
device i/o & irq [rust], pci subsystem [rust], rust, the rest · Maintainers:
Danilo Krummrich, Alice Ryhl, Daniel Almeida, Miguel Ojeda, Linus Torvalds
From: Joel Fernandes <joelagnelf@nvidia.com> Add a `Device::resource_flags()` method to the PCI Rust abstraction, wrapping the C-side static inline `pci_resource_flags()`. The flags returned correspond to the `IORESOURCE` bitmask carried by a PCI BAR's `struct resource`. The immediate motivation is BAR layout discovery on NVIDIA GPUs: a 64-bit BAR consumes two consecutive Linux PCI resource slots (the lower 32 bits at index N and the upper 32 bits at index N+1, with the latter having no flags or size of its own). Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com> Signed-off-by: Eliot Courtney <redacted> --- This is patch 1 of Joel's nova-core mm prerequisites series [1], reposted with no code changes. The rest of that series was folded into the PRAMIN series [2], which is now in drm-rust-next and didn't carry this patch. The upcoming nova-core memory management changes still need resource_flags(). This is based on drm-rust-next. [1] https://lore.kernel.org/all/20260518180342.2387845-2-joelagnelf@nvidia.com/ (local) [2] https://lore.kernel.org/all/20260827-pramin-split-v3-0-24b24d7afc52@nvidia.com/ (local) --- rust/helpers/pci.c | 6 ++++++ rust/kernel/io/resource.rs | 8 ++++++++ rust/kernel/pci.rs | 14 ++++++++++++++ 3 files changed, 28 insertions(+)
diff --git a/rust/helpers/pci.c b/rust/helpers/pci.c
index a714cc2bfb7a..3686e405160d 100644
--- a/rust/helpers/pci.c
+++ b/rust/helpers/pci.c@@ -19,6 +19,12 @@ __rust_helper resource_size_t rust_helper_pci_resource_len(struct pci_dev *pdev, return pci_resource_len(pdev, bar); } +__rust_helper unsigned long rust_helper_pci_resource_flags(const struct pci_dev *pdev, + int bar) +{ + return pci_resource_flags(pdev, bar); +} + __rust_helper bool rust_helper_dev_is_pci(const struct device *dev) { return dev_is_pci(dev);
diff --git a/rust/kernel/io/resource.rs b/rust/kernel/io/resource.rs
index 17b0c174cfc5..0d3b34f83334 100644
--- a/rust/kernel/io/resource.rs
+++ b/rust/kernel/io/resource.rs@@ -226,10 +226,18 @@ impl Flags { /// Resource represents a memory region that must be ioremaped using `ioremap_np`. pub const IORESOURCE_MEM_NONPOSTED: Flags = Flags::new(bindings::IORESOURCE_MEM_NONPOSTED); + /// Memory region uses a 64-bit address (consumes two consecutive PCI resource slots). + pub const IORESOURCE_MEM_64: Flags = Flags::new(bindings::IORESOURCE_MEM_64); + // Always inline to optimize out error path of `build_assert`. #[inline(always)] const fn new(value: u32) -> Self { build_assert!(value as u64 <= c_ulong::MAX as u64); Flags(value as c_ulong) } + + /// Wrap a raw `c_ulong` value returned by a C API into [`Flags`]. + pub(crate) const fn from_raw(value: c_ulong) -> Self { + Flags(value) + } }
diff --git a/rust/kernel/pci.rs b/rust/kernel/pci.rs
index 3ec897709e89..19a219847c17 100644
--- a/rust/kernel/pci.rs
+++ b/rust/kernel/pci.rs@@ -17,6 +17,7 @@ from_result, to_result, // }, + io::resource, prelude::*, str::CStr, types::Opaque,
@@ -439,6 +440,19 @@ pub fn resource_len(&self, bar: u32) -> Result<bindings::resource_size_t> { Ok(unsafe { bindings::pci_resource_len(self.as_raw(), bar.try_into()?) }) } + /// Returns the resource flags (`IORESOURCE_*`) of the given PCI BAR. + pub fn resource_flags(&self, bar: u32) -> Result<resource::Flags> { + if !Bar::index_is_valid(bar) { + return Err(EINVAL); + } + + // SAFETY: + // - `bar` is a valid bar number, as guaranteed by the above call to `Bar::index_is_valid`, + // - by its type invariant `self.as_raw` is always a valid pointer to a `struct pci_dev`. + let raw = unsafe { bindings::pci_resource_flags(self.as_raw(), bar.try_into()?) }; + Ok(resource::Flags::from_raw(raw)) + } + /// Returns the PCI class as a `Class` struct. #[inline] pub fn pci_class(&self) -> Class {
--- base-commit: e6a2c988ed96a5a3af51ed97ecba980521bf2fc0 change-id: 20260907-pci-resource-flags-b7addba0b34f Best regards, -- Eliot Courtney [off-list ref]