[PATCH v5 1/6] PCI/IOV: Return unsigned int from pci_sriov_get_totalvfs()

[PATCH v5 1/6] PCI/IOV: Return unsigned int from pci_sriov_get_totalvfs()

[Zhi Wang]

pci_sriov_get_totalvfs() reports a VF count, not an errno-style
status. It returns 0 when SR-IOV is unavailable or the device is not a
PF, and otherwise returns the PF's driver_max_VFs value.

driver_max_VFs is stored as a u16 in struct pci_sriov. It is derived
from the SR-IOV TotalVFs field or from a driver-provided limit, so the
implementation cannot return a negative value.

Change the declaration, CONFIG_PCI_IOV stub, and implementation to
return unsigned int.

Suggested-by: Alexandre Courbot <acourbot@nvidia.com>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: David Laight <david.laight.linux@gmail.com>
Cc: Gary Guo <gary@garyguo.net>
Cc: linux-pci@vger.kernel.org
Link: https://lore.kernel.org/all/DJHPRE4TGGT8.BUTMYOF5YE05@nvidia.com/
Signed-off-by: Zhi Wang <zhiw@nvidia.com>
---
 drivers/pci/iov.c   | 2 +-
 include/linux/pci.h | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
index b0d24839c084..9d408fb8ac25 100644
--- a/drivers/pci/iov.c
+++ b/drivers/pci/iov.c
@@ -1283,7 +1283,7 @@ EXPORT_SYMBOL_GPL(pci_sriov_set_totalvfs);
  * SRIOV capability value of TotalVFs or the value of driver_max_VFs
  * if the driver reduced it.  Otherwise 0.
  */
-int pci_sriov_get_totalvfs(struct pci_dev *dev)
+unsigned int pci_sriov_get_totalvfs(struct pci_dev *dev)
 {
 	if (!dev->is_physfn)
 		return 0;
diff --git a/include/linux/pci.h b/include/linux/pci.h
index ebb5b9d76360..2b9c61de5f67 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -2569,7 +2569,7 @@ void pci_iov_remove_virtfn(struct pci_dev *dev, int id);
 int pci_num_vf(struct pci_dev *dev);
 int pci_vfs_assigned(struct pci_dev *dev);
 int pci_sriov_set_totalvfs(struct pci_dev *dev, u16 numvfs);
-int pci_sriov_get_totalvfs(struct pci_dev *dev);
+unsigned int pci_sriov_get_totalvfs(struct pci_dev *dev);
 int pci_sriov_configure_simple(struct pci_dev *dev, int nr_virtfn);
 resource_size_t pci_iov_resource_size(const struct pci_dev *dev, int resno);
 int pci_iov_vf_bar_set_size(struct pci_dev *dev, int resno, int size);
@@ -2622,7 +2622,7 @@ static inline int pci_vfs_assigned(struct pci_dev *dev)
 { return 0; }
 static inline int pci_sriov_set_totalvfs(struct pci_dev *dev, u16 numvfs)
 { return 0; }
-static inline int pci_sriov_get_totalvfs(struct pci_dev *dev)
+static inline unsigned int pci_sriov_get_totalvfs(struct pci_dev *dev)
 { return 0; }
 #define pci_sriov_configure_simple	NULL
 static inline resource_size_t pci_iov_resource_size(const struct pci_dev *dev,
-- 
2.53.0

[PATCH v5 2/6] rust: pci: add sriov_get_totalvfs() helper

[Zhi Wang]

Expose pci_sriov_get_totalvfs() to Rust PCI drivers so they can query
how many SR-IOV VFs a device supports.

Use a conditional C helper because the !CONFIG_PCI_IOV version of
pci_sriov_get_totalvfs() is a static inline function and is therefore
not emitted into the Rust bindings. Return Option<NonZero<u16>> so Rust
callers must handle the zero value that represents unavailable SR-IOV.

Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Cc: Alexandre Courbot <acourbot@nvidia.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: David Laight <david.laight.linux@gmail.com>
Cc: Gary Guo <gary@garyguo.net>
Cc: linux-pci@vger.kernel.org
Link: https://lore.kernel.org/all/DJHPRE4TGGT8.BUTMYOF5YE05@nvidia.com/
Signed-off-by: Zhi Wang <zhiw@nvidia.com>
---
 rust/helpers/pci.c |  8 ++++++++
 rust/kernel/pci.rs | 13 +++++++++++++
 2 files changed, 21 insertions(+)

diff --git a/rust/helpers/pci.c b/rust/helpers/pci.c
index e44905317d75..4ebf256dff23 100644
--- a/rust/helpers/pci.c
+++ b/rust/helpers/pci.c
@@ -24,6 +24,14 @@ __rust_helper bool rust_helper_dev_is_pci(const struct device *dev)
 	return dev_is_pci(dev);
 }
 
+#ifndef CONFIG_PCI_IOV
+__rust_helper unsigned int
+rust_helper_pci_sriov_get_totalvfs(struct pci_dev *pdev)
+{
+	return pci_sriov_get_totalvfs(pdev);
+}
+#endif
+
 #ifndef CONFIG_PCI_MSI
 __rust_helper int rust_helper_pci_alloc_irq_vectors(struct pci_dev *dev,
 						    unsigned int min_vecs,
diff --git a/rust/kernel/pci.rs b/rust/kernel/pci.rs
index c6d6bd8f251d..9f19ccd5905c 100644
--- a/rust/kernel/pci.rs
+++ b/rust/kernel/pci.rs
@@ -25,6 +25,7 @@
 use core::{
     marker::PhantomData,
     mem::offset_of,
+    num::NonZero,
     ptr::{
         addr_of_mut,
         NonNull, //
@@ -452,6 +453,18 @@ pub fn pci_class(&self) -> Class {
 }
 
 impl<'a> Device<device::Core<'a>> {
+    /// Returns the total number of VFs, or [`None`] if SR-IOV is not available.
+    #[inline]
+    pub fn sriov_get_totalvfs(&self) -> Option<NonZero<u16>> {
+        // SAFETY: `self.as_raw()` is a valid pointer to a `struct pci_dev`.
+        let total_vfs = unsafe { bindings::pci_sriov_get_totalvfs(self.as_raw()) };
+
+        // CAST: The C function returns `unsigned int`, but the value originates
+        // from TotalVFs/driver_max_VFs (which are defined as `u16`), so this cast
+        // cannot truncate.
+        NonZero::new(total_vfs as u16)
+    }
+
     /// Enable memory resources for this device.
     pub fn enable_device_mem(&self) -> Result {
         // SAFETY: `self.as_raw` is guaranteed to be a pointer to a valid `struct pci_dev`.
-- 
2.53.0

Re: [PATCH v5 1/6] PCI/IOV: Return unsigned int from pci_sriov_get_totalvfs()

[sashiko-bot]

> pci_sriov_get_totalvfs() reports a VF count, not an errno-style
> status. It returns 0 when SR-IOV is unavailable or the device is not a
> PF, and otherwise returns the PF's driver_max_VFs value.
> 
> driver_max_VFs is stored as a u16 in struct pci_sriov. It is derived
> from the SR-IOV TotalVFs field or from a driver-provided limit, so the
> implementation cannot return a negative value.
> 
> Change the declaration, CONFIG_PCI_IOV stub, and implementation to
> return unsigned int.
> 
> Suggested-by: Alexandre Courbot <acourbot@nvidia.com>
> Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
> Acked-by: Bjorn Helgaas <bhelgaas@google.com>
> Cc: Bjorn Helgaas <bhelgaas@google.com>
> Cc: David Laight <david.laight.linux@gmail.com>
> Cc: Gary Guo <gary@garyguo.net>
> Cc: linux-pci@vger.kernel.org
> Link: https://lore.kernel.org/all/DJHPRE4TGGT8.BUTMYOF5YE05@nvidia.com/
> Signed-off-by: Zhi Wang <zhiw@nvidia.com>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260722073913.1807677-1-zhiw@nvidia.com?part=1

Re: [PATCH v5 2/6] rust: pci: add sriov_get_totalvfs() helper

[sashiko-bot]

> Expose pci_sriov_get_totalvfs() to Rust PCI drivers so they can query
> how many SR-IOV VFs a device supports.
> 
> Use a conditional C helper because the !CONFIG_PCI_IOV version of
> pci_sriov_get_totalvfs() is a static inline function and is therefore
> not emitted into the Rust bindings. Return Option<NonZero<u16>> so Rust
> callers must handle the zero value that represents unavailable SR-IOV.
> 
> Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
> Cc: Alexandre Courbot <acourbot@nvidia.com>
> Cc: Bjorn Helgaas <bhelgaas@google.com>
> Cc: David Laight <david.laight.linux@gmail.com>
> Cc: Gary Guo <gary@garyguo.net>
> Cc: linux-pci@vger.kernel.org
> Link: https://lore.kernel.org/all/DJHPRE4TGGT8.BUTMYOF5YE05@nvidia.com/
> Signed-off-by: Zhi Wang <zhiw@nvidia.com>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260722073913.1807677-1-zhiw@nvidia.com?part=2

Re: [PATCH v5 2/6] rust: pci: add sriov_get_totalvfs() helper

[Alexandre Courbot]

On Wed Jul 22, 2026 at 4:39 PM JST, Zhi Wang wrote:
> Expose pci_sriov_get_totalvfs() to Rust PCI drivers so they can query
> how many SR-IOV VFs a device supports.
>
> Use a conditional C helper because the !CONFIG_PCI_IOV version of
> pci_sriov_get_totalvfs() is a static inline function and is therefore
> not emitted into the Rust bindings. Return Option<NonZero<u16>> so Rust
> callers must handle the zero value that represents unavailable SR-IOV.
>
> Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
> Cc: Alexandre Courbot <acourbot@nvidia.com>
> Cc: Bjorn Helgaas <bhelgaas@google.com>
> Cc: David Laight <david.laight.linux@gmail.com>
> Cc: Gary Guo <gary@garyguo.net>
> Cc: linux-pci@vger.kernel.org
> Link: https://lore.kernel.org/all/DJHPRE4TGGT8.BUTMYOF5YE05@nvidia.com/
> Signed-off-by: Zhi Wang <zhiw@nvidia.com>

The series looks ready to me, but we need a Ack on this patch to take it
through drm-rust-next - Danilo, does this look ok to you?