[PATCH v9 22/23] gpu: nova-core: mm: Add PRAMIN aperture self-tests

[Joel Fernandes <joelagnelf@nvidia.com>]

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 022b156de0da..5f4199e41d16 100644
--- a/drivers/gpu/nova-core/gpu.rs
+++ b/drivers/gpu/nova-core/gpu.rs
@@ -365,6 +365,9 @@ fn run_mm_selftests(self: Pin<&mut Self>, pdev: &pci::Device<device::Bound>) ->
 
         let mmu_version = MmuVersion::from(self.spec.chipset.arch());
 
+        // 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 707794f49add..bf87eb84805f 100644
--- a/drivers/gpu/nova-core/mm/pramin.rs
+++ b/drivers/gpu/nova-core/mm/pramin.rs
@@ -195,6 +195,11 @@ 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.
@@ -291,3 +296,207 @@ 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.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