[PATCH v10 20/21] gpu: nova-core: mm: Add PRAMIN aperture self-tests

Joel Fernandes
2026-03-31T21:21:56Z

Add self-tests for the PRAMIN aperture mechanism to verify correct
operation during GPU probe. The tests validate various alignment
requirements and corner cases.

The tests are default disabled and behind CONFIG_NOVA_MM_SELFTESTS.
When enabled, tests run after GSP boot during probe.

Cc: Nikola Djukic <ndjukic@nvidia.com>
Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
---
drivers/gpu/nova-core/gpu.rs | 3 +
drivers/gpu/nova-core/mm/pramin.rs | 209 +++++++++++++++++++++++++++++
2 files changed, 212 insertions(+)

diff --git a/drivers/gpu/nova-core/gpu.rs b/drivers/gpu/nova-core/gpu.rs
index 021fc7cc7247..8206ec015b26 100644
--- a/drivers/gpu/nova-core/gpu.rs
+++ b/drivers/gpu/nova-core/gpu.rs
@@ -355,6 +355,9 @@ pub(crate) fn run_selftests(
fn run_mm_selftests(self: Pin<&mut Self>, pdev: &pci::Device<device::Bound>) -> Result {
use crate::driver::BAR1_SIZE;

+ // PRAMIN aperture self-tests.
+ crate::mm::pramin::run_self_test(pdev.as_ref(), self.mm.pramin(), self.spec.chipset)?;
+
// BAR1 self-tests.
let bar1 = Arc::pin_init(
pdev.iomap_region_sized::<BAR1_SIZE>(1, c"nova-core/bar1"),
diff --git a/drivers/gpu/nova-core/mm/pramin.rs b/drivers/gpu/nova-core/mm/pramin.rs
index fde0eb30eaeb..059d00c49611 100644
--- a/drivers/gpu/nova-core/mm/pramin.rs
+++ b/drivers/gpu/nova-core/mm/pramin.rs
@@ -180,6 +180,11 @@ pub(crate) fn new(
}))
}

+ /// Returns the valid VRAM region for this PRAMIN instance.
+ pub(crate) fn vram_region(&self) -> &Range<u64> {
+ &self.vram_region
+ }
+
/// Acquire exclusive PRAMIN access.
///
/// Returns a [`PraminWindow`] guard that provides VRAM read/write accessors.
@@ -278,3 +283,207 @@ fn compute_window(
define_pramin_write!(try_write32, u32);
define_pramin_write!(try_write64, u64);
}
+
+/// Offset within the VRAM region to use as the self-test area.
+#[cfg(CONFIG_NOVA_MM_SELFTESTS)]
+const SELFTEST_REGION_OFFSET: usize = 0x1000;
+
+/// Test read/write at byte-aligned locations.
+#[cfg(CONFIG_NOVA_MM_SELFTESTS)]
+fn test_byte_readwrite(
+ dev: &kernel::device::Device,
+ win: &mut PraminWindow<'_>,
+ base: usize,
+) -> Result {
+ for i in 0u8..4 {
+ let offset = base + 1 + usize::from(i);
+ let val = 0xA0 + i;
+ win.try_write8(offset, val)?;
+ let read_val = win.try_read8(offset)?;
+ if read_val != val {
+ dev_err!(
+ dev,
+ "PRAMIN: FAIL - offset {:#x}: wrote {:#x}, read {:#x}\n",
+ offset,
+ val,
+ read_val
+ );
+ return Err(EIO);
+ }
+ }
+ Ok(())
+}
+
+/// Test writing a `u32` and reading back as individual `u8`s.
+#[cfg(CONFIG_NOVA_MM_SELFTESTS)]
+fn test_u32_as_bytes(
+ dev: &kernel::device::Device,
+ win: &mut PraminWindow<'_>,
+ base: usize,
+) -> Result {
+ let offset = base + 0x10;
+ let val: u32 = 0xDEADBEEF;
+ win.try_write32(offset, val)?;
+
+ // Read back as individual bytes (little-endian: EF BE AD DE).
+ let expected_bytes: [u8; 4] = [0xEF, 0xBE, 0xAD, 0xDE];
+ for (i, &expected) in expected_bytes.iter().enumerate() {
+ let read_val = win.try_read8(offset + i)?;
+ if read_val != expected {
+ dev_err!(
+ dev,
+ "PRAMIN: FAIL - offset {:#x}: expected {:#x}, read {:#x}\n",
+ offset + i,
+ expected,
+ read_val
+ );
+ return Err(EIO);
+ }
+ }
+ Ok(())
+}
+
+/// Test window repositioning across 1MB boundaries.
+#[cfg(CONFIG_NOVA_MM_SELFTESTS)]
+fn test_window_reposition(
+ dev: &kernel::device::Device,
+ win: &mut PraminWindow<'_>,
+ base: usize,
+) -> Result {
+ let offset_a: usize = base;
+ let offset_b: usize = base + 0x200000; // base + 2MB (different 1MB region).
+ let val_a: u32 = 0x11111111;
+ let val_b: u32 = 0x22222222;
+
+ win.try_write32(offset_a, val_a)?;
+ win.try_write32(offset_b, val_b)?;
+
+ let read_b = win.try_read32(offset_b)?;
+ if read_b != val_b {
+ dev_err!(
+ dev,
+ "PRAMIN: FAIL - offset {:#x}: expected {:#x}, read {:#x}\n",
+ offset_b,
+ val_b,
+ read_b
+ );
+ return Err(EIO);
+ }
+
+ let read_a = win.try_read32(offset_a)?;
+ if read_a != val_a {
+ dev_err!(
+ dev,
+ "PRAMIN: FAIL - offset {:#x}: expected {:#x}, read {:#x}\n",
+ offset_a,
+ val_a,
+ read_a
+ );
+ return Err(EIO);
+ }
+ Ok(())
+}
+
+/// Test that offsets outside the VRAM region are rejected.
+#[cfg(CONFIG_NOVA_MM_SELFTESTS)]
+fn test_invalid_offset(
+ dev: &kernel::device::Device,
+ win: &mut PraminWindow<'_>,
+ vram_end: u64,
+) -> Result {
+ let invalid_offset: usize = vram_end.into_safe_cast();
+ let result = win.try_read32(invalid_offset);
+ if result.is_ok() {
+ dev_err!(
+ dev,
+ "PRAMIN: FAIL - read at invalid offset {:#x} should have failed\n",
+ invalid_offset
+ );
+ return Err(EIO);
+ }
+ Ok(())
+}
+
+/// Test that misaligned multi-byte accesses are rejected.
+#[cfg(CONFIG_NOVA_MM_SELFTESTS)]
+fn test_misaligned_access(
+ dev: &kernel::device::Device,
+ win: &mut PraminWindow<'_>,
+ base: usize,
+) -> Result {
+ // `u16` at odd offset (not 2-byte aligned).
+ let offset_u16 = base + 0x21;
+ if win.try_write16(offset_u16, 0xABCD).is_ok() {
+ dev_err!(
+ dev,
+ "PRAMIN: FAIL - misaligned u16 write at {:#x} should have failed\n",
+ offset_u16
+ );
+ return Err(EIO);
+ }
+
+ // `u32` at 2-byte-aligned (not 4-byte-aligned) offset.
+ let offset_u32 = base + 0x32;
+ if win.try_write32(offset_u32, 0x12345678).is_ok() {
+ dev_err!(
+ dev,
+ "PRAMIN: FAIL - misaligned u32 write at {:#x} should have failed\n",
+ offset_u32
+ );
+ return Err(EIO);
+ }
+
+ // `u64` read at 4-byte-aligned (not 8-byte-aligned) offset.
+ let offset_u64 = base + 0x44;
+ if win.try_read64(offset_u64).is_ok() {
+ dev_err!(
+ dev,
+ "PRAMIN: FAIL - misaligned u64 read at {:#x} should have failed\n",
+ offset_u64
+ );
+ return Err(EIO);
+ }
+ Ok(())
+}
+
+/// Run PRAMIN self-tests during boot if self-tests are enabled.
+#[cfg(CONFIG_NOVA_MM_SELFTESTS)]
+pub(crate) fn run_self_test(
+ dev: &kernel::device::Device,
+ pramin: &Pramin,
+ chipset: crate::gpu::Chipset,
+) -> Result {
+ use crate::gpu::Architecture;
+
+ // PRAMIN uses NV_PBUS_BAR0_WINDOW which is only available on pre-Hopper GPUs.
+ // Hopper+ uses NV_XAL_EP_BAR0_WINDOW instead, requiring a separate HAL that
+ // has not been implemented yet.
+ if !matches!(
+ chipset.arch(),
+ Architecture::Turing | Architecture::Ampere | Architecture::Ada
+ ) {
+ dev_info!(
+ dev,
+ "PRAMIN: Skipping self-tests for {:?} (only pre-Hopper supported)\n",
+ chipset
+ );
+ return Ok(());
+ }
+
+ dev_info!(dev, "PRAMIN: Starting self-test...\n");
+
+ let vram_region = pramin.vram_region();
+ let base: usize = vram_region.start.into_safe_cast();
+ let base = base + SELFTEST_REGION_OFFSET;
+ let vram_end = vram_region.end;
+ let mut win = pramin.get_window()?;
+
+ test_byte_readwrite(dev, &mut win, base)?;
+ test_u32_as_bytes(dev, &mut win, base)?;
+ test_window_reposition(dev, &mut win, base)?;
+ test_invalid_offset(dev, &mut win, vram_end)?;
+ test_misaligned_access(dev, &mut win, base)?;
+
+ dev_info!(dev, "PRAMIN: All self-tests PASSED\n");
+ Ok(())
+}
--
2.34.1