[PATCH 13/14] gpu: nova-core: publish typed SR-IOV PF data for VF drivers

[Zhi Wang]

Nova-core is the PF-side GPU driver, but it does not implement the PCI
callback for `sriov_numvfs`. Userspace therefore cannot enable or
disable VFs on GPUs bound to the driver, and no typed PF data is
available before a VF is created.

Embed a `VfRegistration` in the pinned `NovaCore` driver data and
publish unit data, `()`, as a typed readiness marker on SR-IOV PFs. The
registration remains inactive on conventional PCI functions and rejects
VFs, so nova-core can keep using the ordinary `pci::Driver` abstraction
with or without `CONFIG_PCI_IOV`.

Implement `sriov_configure()` using the verified PF view and pinned
driver data. Managed SR-IOV removes every VF before the inline
registration and the rest of `NovaCore` are dropped.

Signed-off-by: Zhi Wang <zhiw@xxxxxxxxxx>
---
 drivers/gpu/nova-core/driver.rs | 33 ++++++++++++++++++++++++++++++---
 1 file changed, 30 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/nova-core/driver.rs b/drivers/gpu/nova-core/driver.rs
index a5b9a50cbaca..1373417386a2 100644
--- a/drivers/gpu/nova-core/driver.rs
+++ b/drivers/gpu/nova-core/driver.rs
@@ -35,6 +35,10 @@
 
 #[pin_data]
 pub(crate) struct NovaCore<'bound> {
+    #[cfg(CONFIG_PCI_IOV)]
+    #[allow(clippy::type_complexity)]
+    #[pin]
+    _vf_registration: pci::VfRegistration<'bound, CovariantForLt!(())>,
     #[pin]
     pub(crate) gpu: Gpu<'bound>,
     bar: pci::Bar<'bound, BAR0_SIZE>,
@@ -107,10 +111,18 @@ fn probe<'bound>(
         pin_init::pin_init_scope(move || {
             dev_dbg!(pdev, "Probe Nova Core GPU driver.\n");
 
-            pdev.enable_device_mem()?;
-            pdev.set_master();
-
             Ok(try_pin_init!(NovaCore {
+                #[cfg(CONFIG_PCI_IOV)]
+                // SAFETY:
+                // - probe has exclusive access before SR-IOV can be enabled;
+                // - the registration is pinned in driver data and is its first field;
+                // - no other registration is created for this device; and
+                // - the PCI adapter uses managed SR-IOV.
+                _vf_registration <- unsafe { pci::VfRegistration::new(pdev, Ok(())) },
+                _: {
+                    pdev.enable_device_mem()?;
+                    pdev.set_master();
+                },
                 bar: pdev.iomap_region_sized::<BAR0_SIZE>(0, c"nova-core/bar0")?,
                 bar1: {
                     let bar1_idx = bar1_resource_index(pdev)?;
@@ -149,4 +161,19 @@ fn probe<'bound>(
             }))
         })
     }
+
+    #[cfg(CONFIG_PCI_IOV)]
+    fn sriov_configure<'bound>(
+        dev: &'bound pci::sriov::Device<Core<'_>>,
+        _this: Pin<&Self::Data<'bound>>,
+        nr_virtfn: i32,
+    ) -> Result<i32> {
+        if nr_virtfn == 0 {
+            dev.disable_sriov();
+        } else {
+            dev.enable_sriov(nr_virtfn)?;
+        }
+
+        Ok(nr_virtfn)
+    }
 }