[PATCH v3 04/31] gpu: nova-core: gpu: add a channel ID pool for vGPU

[Zhi Wang]

Channel ID reservations need a GPU-owned pool shared by vGPU instances.

The pool must remain at a stable address while its reservations exist.
Its storage also needs to remain available throughout GPU cleanup.

Create a private pinned ChannelIdPool with a single 2048-channel
capacity constant.

Cc: Alexandre Courbot <acourbot@xxxxxxxxxx>
Suggested-by: Eliot Courtney <ecourtney@xxxxxxxxxx>
Signed-off-by: Zhi Wang <zhiw@xxxxxxxxxx>
---
 drivers/gpu/nova-core/gpu.rs         | 9 +++++++++
 drivers/gpu/nova-core/gpu/channel.rs | 4 ++++
 2 files changed, 13 insertions(+)

diff --git a/drivers/gpu/nova-core/gpu.rs b/drivers/gpu/nova-core/gpu.rs
index 650bef8b5f44..c239b6614d44 100644
--- a/drivers/gpu/nova-core/gpu.rs
+++ b/drivers/gpu/nova-core/gpu.rs
@@ -48,6 +48,7 @@
         GpuMm,
         VramAddress, //
     },
+    num,
     vgpu::VgpuState, //
 };
 
@@ -56,6 +57,10 @@
 mod hal;
 mod regs;
 
+use self::channel::TOTAL_CHANNELS;
+
+pub(crate) use self::channel::ChannelIdPool;
+
 macro_rules! define_chipset {
     ({ $($variant:ident = $value:expr),* $(,)* }) =>
     {
@@ -335,6 +340,8 @@ pub(crate) struct Gpu<'gpu> {
     /// GSP and its resources.
     #[pin]
     gsp_resources: GspResources<'gpu>,
+    #[pin]
+    chid_pool: ChannelIdPool,
     /// System memory page required for flushing all pending GPU-side memory writes done through
     /// PCIE into system memory, via sysmembar (A GPU-initiated HW memory-barrier operation).
     ///
@@ -417,6 +424,8 @@ pub(crate) fn new<'a>(
             // Initialize this early because `gsp_resources` depends on it.
             sysmem_flush: SysmemFlush::register(dev, bar, spec.chipset)?,
 
+            chid_pool <- ChannelIdPool::new(cv!(num::u32_as_usize(TOTAL_CHANNELS))),
+
             gsp_resources <- try_pin_init!(GspResources {
                 device: pdev,
 
diff --git a/drivers/gpu/nova-core/gpu/channel.rs b/drivers/gpu/nova-core/gpu/channel.rs
index 485efaba059d..75666c6768e6 100644
--- a/drivers/gpu/nova-core/gpu/channel.rs
+++ b/drivers/gpu/nova-core/gpu/channel.rs
@@ -21,6 +21,10 @@
     }, //
 };
 
+// TODO: Query the channel capacity through GMCAPI once an equivalent of
+// NV2080_CTRL_CMD_INTERNAL_FIFO_GET_NUM_CHANNELS is available.
+pub(super) const TOTAL_CHANNELS: u32 = 2048;
+
 /// Pool for tracking reservations of channel IDs.
 #[pin_data]
 pub(crate) struct ChannelIdPool {