[PATCH 0/2] gpu: nova-core: add two prerequisites for the r000 GSP firmware

[PATCH 0/2] gpu: nova-core: add two prerequisites for the r000 GSP firmware

[John Hubbard]

Here are two preparatory changes for (or more accurately, from) the r000
GSP firmware series [1], which enables nova-core to work with the GSP
firmware for r615+ releases.

Both of these patches stand on their own, so posting them now helps
avoid reviewing a huge-er r000 series. :)

* For the Rust PCI abstraction, add an accessor for the PCI domain
  number.

* Factor out the shutdown path's check for a suspended GSP. The r000
  boot sequence needs the same check, so it gets factored out and
  cleaned up a bit at the same time, by using register!() for the bit 31
  access.

This applies to today's drm-rust-next: commit a7cdb17ca0d7.

An LLM coding assistant (Claude Code) helped write both patches, but I
have fussed over every line of both the code and the commit messages.
The LLM also drafted the first version of this letter, which I've
completely rewritten, because it totally missed the point. All of the
points. :)

Testing: booted nova-core on my 3-GPU test system (Turing, Ampere and
Blackwell GPUs) with all KUnit and built-in Nova tests enabled, as
usual.

[1] https://lore.kernel.org/all/20260918010719.1176945-1-jhubbard@nvidia.com/


John Hubbard (2):
  rust: pci: add domain_nr() accessor
  gpu: nova-core: factor out and expose Falcon::is_processor_suspended()

 drivers/gpu/nova-core/falcon/gsp.rs |  7 +++++++
 drivers/gpu/nova-core/gsp/boot.rs   |  6 ++----
 drivers/gpu/nova-core/regs.rs       |  5 +++++
 rust/helpers/pci.c                  |  5 +++++
 rust/kernel/pci.rs                  | 14 ++++++++++++++
 5 files changed, 33 insertions(+), 4 deletions(-)


base-commit: a7cdb17ca0d7ce67e9f3a52d39edd60f03223729
-- 
2.56.0

[PATCH 1/2] rust: pci: add domain_nr() accessor

[John Hubbard]

The nova-core driver has to send the GPU's PCI location to the GPU's
firmware as one word that holds the domain, the bus and the device
number.

The PCI abstraction has dev_id(), which packs the bus, the device and
the function into one value. It has no accessor that reports the domain.

Add an accessor for the domain number.

Suggested-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---
 rust/helpers/pci.c |  5 +++++
 rust/kernel/pci.rs | 14 ++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/rust/helpers/pci.c b/rust/helpers/pci.c
index a8540f90b13c..49f2c089d236 100644
--- a/rust/helpers/pci.c
+++ b/rust/helpers/pci.c
@@ -7,6 +7,11 @@ __rust_helper u16 rust_helper_pci_dev_id(struct pci_dev *dev)
 	return PCI_DEVID(dev->bus->number, dev->devfn);
 }
 
+__rust_helper int rust_helper_pci_domain_nr(struct pci_dev *dev)
+{
+	return pci_domain_nr(dev->bus);
+}
+
 __rust_helper resource_size_t
 rust_helper_pci_resource_start(struct pci_dev *pdev, int bar)
 {
diff --git a/rust/kernel/pci.rs b/rust/kernel/pci.rs
index 769d01d23429..57718e48208d 100644
--- a/rust/kernel/pci.rs
+++ b/rust/kernel/pci.rs
@@ -408,6 +408,20 @@ pub fn dev_id(&self) -> u16 {
         unsafe { bindings::pci_dev_id(self.as_raw()) }
     }
 
+    /// Returns the PCI domain number of the bus that this device is on.
+    #[inline]
+    pub fn domain_nr(&self) -> u32 {
+        // SAFETY: By its type invariant `self.as_raw` is always a valid pointer to a
+        // `struct pci_dev`.
+        let domain_nr = unsafe { bindings::pci_domain_nr(self.as_raw()) };
+
+        // CAST: `pci_domain_nr()` returns an `int`, but a registered bus never has a negative
+        // domain, because `pci_register_host_bridge()` fails when the domain allocation fails.
+        // A negative value here is a kernel bug rather than a condition for a caller to handle.
+        debug_assert!(domain_nr >= 0);
+        domain_nr as u32
+    }
+
     /// Returns the PCI subsystem vendor ID.
     #[inline]
     pub fn subsystem_vendor_id(&self) -> u16 {
-- 
2.56.0

[PATCH 2/2] gpu: nova-core: factor out and expose Falcon::is_processor_suspended()

[John Hubbard]

The r000 boot protocol requires the driver to wait for the GSP suspend
bit after each load-and-execute event. The shutdown path already does
this.

The boot sequence will soon need this same functionality, so factor it
out into a method, and put it in it's logical location as well, as a new
method of Falcon<Gsp>.

Also, use register!() for this, instead of manually masking off bit 31.
As usual, that results in much more readable code.

No functional changes.

Co-developed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---
 drivers/gpu/nova-core/falcon/gsp.rs | 7 +++++++
 drivers/gpu/nova-core/gsp/boot.rs   | 6 ++----
 drivers/gpu/nova-core/regs.rs       | 5 +++++
 3 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/nova-core/falcon/gsp.rs b/drivers/gpu/nova-core/falcon/gsp.rs
index 1faefaede9fe..54247691b53c 100644
--- a/drivers/gpu/nova-core/falcon/gsp.rs
+++ b/drivers/gpu/nova-core/falcon/gsp.rs
@@ -47,6 +47,13 @@ fn pfalcon2(io: Bar0<'_>) -> Mmio<'_, super::PFalcon2Registers> {
 }
 
 impl<'a> Falcon<'a, Gsp> {
+    /// Returns `true` if GSP-RM has suspended the RISC-V core.
+    pub(crate) fn is_processor_suspended(&self) -> bool {
+        self.pfalcon
+            .read(regs::NV_PFALCON_FALCON_MAILBOX0_LIBOS)
+            .processor_suspended()
+    }
+
     /// Clears the SWGEN0 latch in the GSP falcon.
     ///
     /// While the latch is set, no later message signals the tree, so a caller that consumed a
diff --git a/drivers/gpu/nova-core/gsp/boot.rs b/drivers/gpu/nova-core/gsp/boot.rs
index 1887806dc330..9d5da5b165ac 100644
--- a/drivers/gpu/nova-core/gsp/boot.rs
+++ b/drivers/gpu/nova-core/gsp/boot.rs
@@ -2,7 +2,6 @@
 // SPDX-FileCopyrightText: Copyright (c) 2025-2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
 
 use kernel::{
-    bits,
     io::poll::read_poll_timeout,
     prelude::*,
     time::Delta,
@@ -98,10 +97,9 @@ fn shutdown_gsp(
         cmdq.send_rpc_command(commands::rpc::UnloadingGuestDriver::new(mode))?;
 
         // Wait until GSP signals it is suspended.
-        const LIBOS_INTERRUPT_PROCESSOR_SUSPENDED: u32 = bits::bit_u32(31);
         read_poll_timeout(
-            || Ok(gsp_falcon.read_mailbox0()),
-            |&mb0| mb0 & LIBOS_INTERRUPT_PROCESSOR_SUSPENDED != 0,
+            || Ok(gsp_falcon.is_processor_suspended()),
+            |suspended| *suspended,
             Delta::from_millis(10),
             Delta::from_secs(5),
         )
diff --git a/drivers/gpu/nova-core/regs.rs b/drivers/gpu/nova-core/regs.rs
index df2eddc58efb..3a0c7159fa7e 100644
--- a/drivers/gpu/nova-core/regs.rs
+++ b/drivers/gpu/nova-core/regs.rs
@@ -147,6 +147,11 @@ pub(crate) fn usable_fb_size(self) -> u64 {
         31:0    value => u32;
     }
 
+    /// `MAILBOX0` as LibOS, the kernel that GSP-RM runs on, writes it.
+    pub(crate) NV_PFALCON_FALCON_MAILBOX0_LIBOS(u32) => NV_PFALCON_FALCON_MAILBOX0 {
+        31:31   processor_suspended => bool;
+    }
+
     pub(crate) NV_PFALCON_FALCON_MAILBOX1(u32) @ 0x00000044 {
         31:0    value => u32;
     }
-- 
2.56.0