Re: [PATCH 0/8] rust: pci: add abstractions for SR-IOV capability

[Zhi Wang <zhiw@nvidia.com>]

On Thu, 20 Nov 2025 20:34:44 +0200
Zhi Wang <zhiw@nvidia.com> wrote:

I tested the patches on a L4, they are working perfectly. :) Though we
can't bootstrap a vGPU and actually poke the VF so far, but VF
enabling/disabling works without problem.

[   97.447502] NovaCore 0000:b6:00.0: Enable SR-IOV (PCI ID: NVIDIA, 0x27b8).
[   97.549467] pci 0000:b6:00.4: [10de:27b8] type 00 class 0x030200 PCIe Endpoint
[   97.549499] pci 0000:b6:00.4: enabling Extended Tags
[   97.549570] pci 0000:b6:00.4: Enabling HDA controller
[   97.549894] pci 0000:b6:00.4: Adding to iommu group 88
[   97.550649] NovaCore 0000:b6:00.4: enabling device (0000 -> 0002)
[   97.550745] NovaCore 0000:b6:00.4: probe with driver NovaCore failed with error -22
[  117.248723] NovaCore 0000:b6:00.0: Disable SR-IOV (PCI ID: NVIDIA, 0x27b8).

The repo I am using can be found here:

https://github.com/zhiwang-nvidia/nova-core/tree/rust-for-linux/test-sriov-on-nova-core

Will test them again on the next spin. :)

Z.

> On Thu, 20 Nov 2025 10:03:45 -0500
> Peter Colberg <pcolberg@redhat.com> wrote:
> 
> Hi Peter:
> 
> I met some errors when compiling on driver-core-next branch, you can
> fix those in the next spin.
> 
> Fixes:
> 
> diff --git a/drivers/gpu/nova-core/driver.rs
> b/drivers/gpu/nova-core/driver.rs index ca0d5f8ad54b..730e745cad63
> 100644 --- a/drivers/gpu/nova-core/driver.rs
> +++ b/drivers/gpu/nova-core/driver.rs
> @@ -49,6 +49,7 @@ pub(crate) struct NovaCore {
>      ]
>  );
>  
> +#[vtable]
>  impl pci::Driver for NovaCore {
>      type IdInfo = ();
>      const ID_TABLE: pci::IdTable<Self::IdInfo> = &PCI_TABLE;
> 
> diff --git a/rust/kernel/pci.rs b/rust/kernel/pci.rs
> index d6cc5d7e7cd7..2d68db076f92 100644
> --- a/rust/kernel/pci.rs
> +++ b/rust/kernel/pci.rs
> @@ -292,6 +292,7 @@ macro_rules! pci_device_table {
>  ///     ]
>  /// );
>  ///
> +/// #[vtable]
>  /// impl pci::Driver for MyDriver {
>  ///     type IdInfo = ();
>  ///     const ID_TABLE: pci::IdTable<Self::IdInfo> = &PCI_TABLE;
> 
> The code in the examples should be able to compile.
> 
> You can enable doctest by:
> 
> CONFIG_RUST_KERNEL_DOCTESTS=y
> 
> Then:
> 
> impl Device<device::Bound> {
>     /// Returns the Physical Function (PF) device for a Virtual
> Function (VF) device. ///
>     /// # Examples
>     ///
> 
> snip
> 
>     /// ```
>     /// let pf_pdev = vf_pdev.physfn()?;
>     /// let pf_drvdata = pf_pdev.as_ref().drvdata::<MyDriver>()?;
> 
> I saw this part is not able to be compiled.^
> 
> Z.
> 
> > On Thu, Nov 20, 2025 at 08:32:13AM +0200, Zhi Wang wrote:
> > > On Wed, 19 Nov 2025 17:19:04 -0500
> > > Peter Colberg <pcolberg@redhat.com> wrote:
> > > 
> > > Hi Peter:
> > > 
> > > Thanks for the patches. :) I will test them with nova-core and
> > > come back with Tested-bys.
> > 
> > Perfect, thanks Zhi.
> > 
> > > Nit: Let's use "kernel vertical" styles on imports. [1]
> > > 
> > > [1]
> > > https://lore.kernel.org/all/20251105120352.77603-1-dakr@kernel.org/
> > 
> > Thanks, done for patch "samples: rust: add SR-IOV driver sample".
> > 
> > Peter
> > 
> > > 
> > > > Add Rust abstractions for the Single Root I/O Virtualization
> > > > (SR-IOV) capability of a PCI device. Provide a minimal set of
> > > > wrappers for the SR-IOV C API to enable and disable SR-IOV for a
> > > > device, and query if a PCI device is a Physical Function (PF) or
> > > > Virtual Function (VF).
> > > > 
> > > > Using the #[vtable] attribute, extend the pci::Driver trait with
> > > > an optional bus callback sriov_configure() that is invoked when
> > > > a user-space application writes the number of VFs to the sysfs
> > > > file `sriov_numvfs` to enable SR-IOV, or zero to disable SR-IOV
> > > > [1].
> > > > 
> > > > Add a method physfn() to return the Physical Function (PF)
> > > > device for a Virtual Function (VF) device in the bound device
> > > > context. Unlike for a PCI driver written in C, guarantee that
> > > > when a VF device is bound to a driver, the underlying PF device
> > > > is bound to a driver, too.
> > > > 
> > > > When a device with enabled VFs is unbound from a driver, invoke
> > > > the sriov_configure() callback to disable SR-IOV before the
> > > > unbind() callback. To ensure the guarantee is upheld, call
> > > > disable_sriov() to remove all VF devices if the driver has not
> > > > done so already.
> > > > 
> > > > This series is based on Danilo Krummrich's series
> > > > "Device::drvdata() and driver/driver interaction (auxiliary)"
> > > > applied to driver-core-next, which similarly guarantees that
> > > > when an auxiliary bus device is bound to a driver, the
> > > > underlying parent device is bound to a driver, too [2].
> > > > 
> > > > Add an SR-IOV driver sample that exercises the SR-IOV capability
> > > > using QEMU's 82576 (igb) emulation and was used to test the
> > > > abstractions [3].
> > > > 
> > > > [1] https://docs.kernel.org/PCI/pci-iov-howto.html
> > > > [2]
> > > > https://lore.kernel.org/rust-for-linux/20251020223516.241050-1-dakr@kernel.org/
> > > > [3] https://www.qemu.org/docs/master/system/devices/igb.html
> > > > 
> > > > Signed-off-by: Peter Colberg <pcolberg@redhat.com>
> > > > ---
> > > > John Hubbard (1):
> > > >       rust: pci: add is_virtfn(), to check for VFs
> > > > 
> > > > Peter Colberg (7):
> > > >       rust: pci: add is_physfn(), to check for PFs
> > > >       rust: pci: add {enable,disable}_sriov(), to control SR-IOV
> > > > capability rust: pci: add num_vf(), to return number of VFs
> > > >       rust: pci: add vtable attribute to pci::Driver trait
> > > >       rust: pci: add bus callback sriov_configure(), to control
> > > > SR-IOV from sysfs rust: pci: add physfn(), to return PF device
> > > > for VF device samples: rust: add SR-IOV driver sample
> > > > 
> > > >  MAINTAINERS                           |   1 +
> > > >  rust/kernel/pci.rs                    | 148
> > > > ++++++++++++++++++++++++++++++++++ samples/rust/Kconfig
> > > >    |  11 +++ samples/rust/Makefile                 |   1 +
> > > >  samples/rust/rust_dma.rs              |   1 +
> > > >  samples/rust/rust_driver_auxiliary.rs |   1 +
> > > >  samples/rust/rust_driver_pci.rs       |   1 +
> > > >  samples/rust/rust_driver_sriov.rs     | 107
> > > > ++++++++++++++++++++++++ 8 files changed, 271 insertions(+)
> > > > ---
> > > > base-commit: e4addc7cc2dfcc19f1c8c8e47f3834b22cb21559
> > > > change-id: 20251026-rust-pci-sriov-ca8f501b2ae3
> > > > 
> > > > Best regards,
> > > 
> > 
> > 
>