[PATCH v2 23/31] gpu: nova-core: gsp: add the GSP_INIT request builder

[John Hubbard]

The r000 GSP boot protocol replaces the separate system-info, registry
and static-info commands with one GSP_INIT request, whose payload is an
NVKV key-value blob rather than a packed struct.

Nova-core has the NVKV codec and the GSP_INIT schema, but nothing that
fills the schema in from a PCI device.

Add the builder. It encodes the PCI identifiers and config mirror range
the RPC path already sends, and the registry entries, whose names carry
the NULL that GSP-RM counts in the encoded length. The PCI location goes
out as domain, bus and device in bits 63:32, 15:8 and 7:0, which is what
GSP-RM decodes, rather than the bus, device and function that PCI_DEVID
packs.

Assisted-by: Cursor:claude-opus-5
Reviewed-by: Timur Tabi <ttabi@xxxxxxxxxx>
Signed-off-by: John Hubbard <jhubbard@xxxxxxxxxx>
---
 drivers/gpu/nova-core/gsp/commands.rs    | 52 +++++++++++++++
 drivers/gpu/nova-core/gsp/fw/commands.rs | 84 +++++++++++++++++++++++-
 2 files changed, 134 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/nova-core/gsp/commands.rs b/drivers/gpu/nova-core/gsp/commands.rs
index d5575c036eb9..0c3832ccf726 100644
--- a/drivers/gpu/nova-core/gsp/commands.rs
+++ b/drivers/gpu/nova-core/gsp/commands.rs
@@ -30,8 +30,16 @@
         },
         fw::{
             self,
+            commands::{
+                GspInitRequest,
+                RegKey, //
+            },
             MsgFunction, //
         },
+        nvkv::{
+            Encodeable,
+            Encoder, //
+        },
     },
     sbuffer::SBufferIter,
     vgpu::VgpuState, //
@@ -259,6 +267,50 @@ pub(crate) fn gpu_name(&self) -> core::result::Result<&str, GpuNameError> {
     }
 }
 
+/// Registry entries the driver sends to GSP-RM on every boot, each with the NULL terminator that
+/// Open RM counts in the encoded name length.
+///
+/// `RMSecBusResetEnable` enables PCI secondary bus reset. `RMForcePcieConfigSave` makes GSP-RM
+/// preserve PCI configuration registers across any PCI reset. `RMDevidCheckIgnore` lets GSP-RM
+/// boot when the PCI device id is absent from its product name database.
+///
+/// [`SetRegistry::new`] carries the same entries for the RPC path, where the names have no
+/// terminator because that encoding appends one.
+const REGISTRY_ENTRIES: &[(&[u8], u32)] = &[
+    (b"RMSecBusResetEnable\0", 1),
+    (b"RMForcePcieConfigSave\0", 1),
+    (b"RMDevidCheckIgnore\0", 1),
+];
+
+/// Builds the NVKV-encoded payload of a `GSP_INIT` request.
+///
+/// The payload carries the system information GSP-RM reads before it starts, and
+/// [`REGISTRY_ENTRIES`] as `REGKEY_NAME` and `REGKEY_VALUE_U32` pairs. GSP-RM requires each name
+/// to be followed by its value, which is the order [`RegKey`] declares them in.
+///
+/// # Errors
+///
+/// - `ENOMEM` if the registry list or the encoder buffer cannot be allocated.
+#[expect(dead_code)]
+pub(crate) fn build_gsp_init_payload(
+    pdev: &pci::Device<device::Bound>,
+    chipset: Chipset,
+    vgpu_state: VgpuState,
+) -> Result<KVVec<u64>> {
+    let mut regkeys = KVVec::new();
+    for &(name, value) in REGISTRY_ENTRIES {
+        regkeys.push(RegKey::new(name, value), GFP_KERNEL)?;
+    }
+    if matches!(vgpu_state, VgpuState::Enabled { .. }) {
+        regkeys.push(RegKey::new(b"RMSetSriovMode\0", 1), GFP_KERNEL)?;
+    }
+
+    let mut encoder = Encoder::new();
+    GspInitRequest::new(pdev, chipset, regkeys).encode(&mut encoder)?;
+
+    Ok(encoder.finish())
+}
+
 pub(crate) use fw::commands::PowerStateLevel;
 
 /// The `UnloadingGuestDriver` command, used to shut down the GSP.
diff --git a/drivers/gpu/nova-core/gsp/fw/commands.rs b/drivers/gpu/nova-core/gsp/fw/commands.rs
index 5cd2d9646de3..c9deee8d23c8 100644
--- a/drivers/gpu/nova-core/gsp/fw/commands.rs
+++ b/drivers/gpu/nova-core/gsp/fw/commands.rs
@@ -245,6 +245,25 @@ pub(crate) enum OorArch {
     Riscv64 = 5,
 }
 
+impl OorArch {
+    /// Returns the variant naming the architecture this kernel is built for.
+    fn host() -> Self {
+        if cfg!(target_arch = "x86_64") {
+            Self::X86_64
+        } else if cfg!(target_arch = "aarch64") {
+            Self::Aarch64
+        } else if cfg!(target_arch = "powerpc64") {
+            Self::Ppc64le
+        } else if cfg!(target_arch = "arm") {
+            Self::Arm
+        } else if cfg!(target_arch = "riscv64") {
+            Self::Riscv64
+        } else {
+            Self::None
+        }
+    }
+}
+
 // TODO[FPRI]: This is a temporary solution to be replaced with the corresponding derive macros once
 // they land.
 impl TryFrom<u32> for OorArch {
@@ -271,7 +290,7 @@ fn from(value: OorArch) -> Self {
 
 nvkv_encode! {
     /// A GSP registry entry.
-    struct RegKey {
+    pub(crate) struct RegKey {
         key_name: Key<&'static [u8], { Self::REGKEY_NAME_KEY }>,
         key_value: Key<u32, { Self::REGKEY_VALUE_U32_KEY }>,
     }
@@ -280,6 +299,15 @@ struct RegKey {
 impl RegKey {
     const REGKEY_NAME_KEY: KeyId = 0x3070;
     const REGKEY_VALUE_U32_KEY: KeyId = 0x3071;
+
+    /// Creates a registry entry. `key_name` must include its NULL terminator, which GSP-RM counts
+    /// in the encoded name length.
+    pub(crate) fn new(key_name: &'static [u8], key_value: u32) -> Self {
+        Self {
+            key_name: key_name.into(),
+            key_value: key_value.into(),
+        }
+    }
 }
 
 impl Encodeable for KVVec<RegKey> {
@@ -317,7 +345,7 @@ impl VfInfo {
 nvkv_encode! {
     /// Payload of the `GSP_INIT` command.
     #[cfg_attr(not(CONFIG_KUNIT), allow(dead_code))]
-    struct GspInitRequest {
+    pub(crate) struct GspInitRequest {
         pci_device_id: Key<u32, { Self::PCI_DEVICE_ID_KEY }>,
         pci_sub_device_id: Key<u32, { Self::PCI_SUBDEVICE_ID_KEY }>,
         pci_revision_id: Key<u32, { Self::PCI_REVISION_ID_KEY }>,
@@ -330,6 +358,27 @@ struct GspInitRequest {
     }
 }
 
+bitfield! {
+    /// PCI bus, device and function, packed the way `PCI_DEVID` packs them, which is what
+    /// [`pci::Device::dev_id`] returns.
+    struct PciDevId(u16) {
+        15:8 bus;
+        7:3 device;
+        2:0 function;
+    }
+}
+
+bitfield! {
+    /// A GPU's PCI location, encoded the way GSP-RM decodes it, matching Open RM's
+    /// `gpuEncodeDomainBusDevice`. Despite the name GSP-RM gives the key, the function number
+    /// is not part of it.
+    struct DomainBusDevice(u64) {
+        63:32 domain;
+        15:8 bus;
+        7:0 device;
+    }
+}
+
 #[cfg_attr(not(CONFIG_KUNIT), allow(dead_code))]
 impl GspInitRequest {
     const PCI_DEVICE_ID_KEY: KeyId = 0x0001;
@@ -339,6 +388,37 @@ impl GspInitRequest {
     const PCI_CONFIG_MIRROR_SIZE_KEY: KeyId = 0x0011;
     const OOR_ARCH_KEY: KeyId = 0x0070;
     const NV_DOMAIN_BUS_DEVICE_FUNC_KEY: KeyId = 0x1020;
+
+    /// Describes `dev` to GSP-RM and asks it to apply `regkeys`.
+    ///
+    /// The same identifiers reach GSP-RM through [`GspSetSystemInfo::init`] on the RPC path.
+    pub(crate) fn new(
+        dev: &pci::Device<device::Bound>,
+        chipset: Chipset,
+        regkeys: KVVec<RegKey>,
+    ) -> Self {
+        let mirror = chipset.pci_config_mirror_range();
+        let dev_id = PciDevId::from(dev.dev_id());
+        let bus_device_func = DomainBusDevice::zeroed()
+            .with_domain(dev.domain_nr())
+            .with_bus(u8::from(dev_id.bus()))
+            .with_device(u8::from(dev_id.device()));
+        let device_id = (u32::from(dev.device_id()) << 16) | u32::from(dev.vendor_id().as_raw());
+        let sub_device_id =
+            (u32::from(dev.subsystem_device_id()) << 16) | u32::from(dev.subsystem_vendor_id());
+
+        Self {
+            pci_device_id: device_id.into(),
+            pci_sub_device_id: sub_device_id.into(),
+            pci_revision_id: u32::from(dev.revision_id()).into(),
+            pci_config_mirror_base: mirror.start.into(),
+            pci_config_mirror_size: (mirror.end - mirror.start).into(),
+            oor_arch: OorArch::host().into(),
+            bus_device_func: u64::from(bus_device_func).into(),
+            regkeys,
+            vf_info: None,
+        }
+    }
 }
 
 // Decode:
-- 
2.55.0