[PATCH v12 19/22] gpu: nova-core: mm: Add BAR1 memory management self-tests

Joel Fernandes
2026-04-25T21:15:54Z

Add self-tests for BAR1 access during driver probe when
CONFIG_NOVA_MM_SELFTESTS is enabled (default disabled). This results in
testing the Vmm, GPU buddy allocator and BAR1 region all of which should
function correctly for the tests to pass.

Cc: Nikola Djukic <ndjukic@nvidia.com>
Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
---
drivers/gpu/nova-core/Kconfig | 10 ++
drivers/gpu/nova-core/driver.rs | 2 +
drivers/gpu/nova-core/gpu.rs | 31 ++++
drivers/gpu/nova-core/mm/bar_user.rs | 244 ++++++++++++++++++++++++++
drivers/gpu/nova-core/mm/pagetable.rs | 35 +++-
5 files changed, 321 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/nova-core/Kconfig b/drivers/gpu/nova-core/Kconfig
index 6513007bf66f..35de55aabcfc 100644
--- a/drivers/gpu/nova-core/Kconfig
+++ b/drivers/gpu/nova-core/Kconfig
@@ -15,3 +15,13 @@ config NOVA_CORE
This driver is work in progress and may not be functional.

If M is selected, the module will be called nova_core.
+
+config NOVA_MM_SELFTESTS
+ bool "Memory management self-tests"
+ depends on NOVA_CORE
+ help
+ Enable self-tests for the memory management subsystem. When enabled,
+ tests are run during GPU probe to verify PRAMIN aperture access,
+ page table walking, and BAR1 virtual memory mapping functionality.
+
+ This is a testing option and is default-disabled.
diff --git a/drivers/gpu/nova-core/driver.rs b/drivers/gpu/nova-core/driver.rs
index e78a682a7f2a..6f95f8672158 100644
--- a/drivers/gpu/nova-core/driver.rs
+++ b/drivers/gpu/nova-core/driver.rs
@@ -97,6 +97,8 @@ fn probe(pdev: &pci::Device<Core>, _info: &Self::IdInfo) -> impl PinInit<Self, E

Ok(try_pin_init!(Self {
gpu <- Gpu::new(pdev, bar.clone(), bar.access(pdev.as_ref())?),
+ // Run optional GPU selftests.
+ _: { gpu.run_selftests(pdev)? },
_reg <- auxiliary::Registration::new(
pdev.as_ref(),
c"nova-drm",
diff --git a/drivers/gpu/nova-core/gpu.rs b/drivers/gpu/nova-core/gpu.rs
index 73a48dba391d..e94f5374eb67 100644
--- a/drivers/gpu/nova-core/gpu.rs
+++ b/drivers/gpu/nova-core/gpu.rs
@@ -346,4 +346,35 @@ pub(crate) fn unbind(&self, dev: &device::Device<device::Core>) {
.inspect(|bar| self.sysmem_flush.unregister(bar))
.is_err());
}
+
+ /// Run selftests on the constructed [`Gpu`].
+ pub(crate) fn run_selftests(
+ mut self: Pin<&mut Self>,
+ pdev: &pci::Device<device::Bound>,
+ ) -> Result {
+ self.as_mut().run_mm_selftests(pdev)?;
+ Ok(())
+ }
+
+ #[cfg(CONFIG_NOVA_MM_SELFTESTS)]
+ fn run_mm_selftests(self: Pin<&mut Self>, pdev: &pci::Device<device::Bound>) -> Result {
+ // BAR1 self-tests.
+ let bar1 = Arc::pin_init(pdev.iomap_region(1, c"nova-core/bar1"), GFP_KERNEL)?;
+ let bar1_access = bar1.access(pdev.as_ref())?;
+
+ crate::mm::bar_user::run_self_test(
+ pdev.as_ref(),
+ &self.mm,
+ bar1_access,
+ self.gsp_static_info.bar1_pde_base,
+ self.spec.chipset,
+ )?;
+
+ Ok(())
+ }
+
+ #[cfg(not(CONFIG_NOVA_MM_SELFTESTS))]
+ fn run_mm_selftests(self: Pin<&mut Self>, _pdev: &pci::Device<device::Bound>) -> Result {
+ Ok(())
+ }
}
diff --git a/drivers/gpu/nova-core/mm/bar_user.rs b/drivers/gpu/nova-core/mm/bar_user.rs
index ab56ecd66fb9..8d996e7eaebe 100644
--- a/drivers/gpu/nova-core/mm/bar_user.rs
+++ b/drivers/gpu/nova-core/mm/bar_user.rs
@@ -154,3 +154,247 @@ fn drop(&mut self) {
}
}
}
+
+/// Run MM subsystem self-tests during probe.
+///
+/// Tests page table infrastructure and `BAR1` MMIO access using the `BAR1`
+/// address space. Uses the `GpuMm`'s buddy allocator to allocate page tables
+/// and test pages as needed.
+#[cfg(CONFIG_NOVA_MM_SELFTESTS)]
+pub(crate) fn run_self_test(
+ pdev: &device::Device<device::Bound>,
+ mm: &GpuMm,
+ bar1: &Bar1,
+ bar1_pdb: u64,
+ chipset: Chipset,
+) -> Result {
+ use kernel::gpu::buddy::{
+ GpuBuddyAllocFlags,
+ GpuBuddyAllocMode, //
+ };
+ use kernel::ptr::Alignment;
+ use kernel::sizes::{
+ SZ_16K,
+ SZ_32K,
+ SZ_4K,
+ SZ_64K, //
+ };
+
+ // Test patterns.
+ const PATTERN_PRAMIN: u32 = 0xDEAD_BEEF;
+ const PATTERN_BAR1: u32 = 0xCAFE_BABE;
+
+ let dev = pdev;
+ dev_info!(dev, "MM: Starting self-test...\n");
+
+ let pdb_addr = VramAddress::new(bar1_pdb);
+
+ // Check if initial page tables are in VRAM.
+ if crate::mm::pagetable::check_pdb_valid(pdev, mm.pramin(), pdb_addr, chipset).is_err() {
+ dev_info!(dev, "MM: Self-test SKIPPED - no valid VRAM page tables\n");
+ return Ok(());
+ }
+
+ // Set up a test page from the buddy allocator.
+ let test_page_blocks = KBox::pin_init(
+ mm.buddy().alloc_blocks(
+ GpuBuddyAllocMode::Simple,
+ SZ_4K.into_safe_cast(),
+ Alignment::new::<SZ_4K>(),
+ GpuBuddyAllocFlags::default(),
+ ),
+ GFP_KERNEL,
+ )?;
+ let test_vram_offset = test_page_blocks.iter().next().ok_or(ENOMEM)?.offset();
+ let test_vram = VramAddress::new(test_vram_offset);
+ let test_pfn = Pfn::from(test_vram);
+
+ // Create a VMM of size 64K to track virtual memory mappings.
+ let mut vmm = Vmm::new(pdb_addr, chipset.mmu_version(), SZ_64K.into_safe_cast())?;
+
+ // Create a test mapping.
+ let mapped = vmm.map_pages(pdev, mm, &[test_pfn], None, true)?;
+ let test_vfn = mapped.vfn_start;
+
+ // Pre-compute test addresses for the PRAMIN to BAR1 read test.
+ let vfn_offset: usize = test_vfn.raw().into_safe_cast();
+ let bar1_base_offset = vfn_offset.checked_mul(PAGE_SIZE).ok_or(EOVERFLOW)?;
+ let bar1_read_offset: usize = bar1_base_offset + 0x100;
+ let vram_read_addr: usize = test_vram.raw() + 0x100;
+
+ // Test 1: Write via PRAMIN, read via BAR1.
+ {
+ let mut window = mm.pramin().get_window(pdev)?;
+ window.try_write32(vram_read_addr, PATTERN_PRAMIN)?;
+ }
+
+ // Read back via BAR1 aperture.
+ let bar1_value = bar1.try_read32(bar1_read_offset)?;
+
+ let test1_passed = if bar1_value == PATTERN_PRAMIN {
+ true
+ } else {
+ dev_err!(
+ dev,
+ "MM: Test 1 FAILED - Expected {:#010x}, got {:#010x}\n",
+ PATTERN_PRAMIN,
+ bar1_value
+ );
+ false
+ };
+
+ // Cleanup - invalidate PTE.
+ vmm.unmap_pages(pdev, mm, mapped)?;
+
+ // Test 2: Two-phase prepare/execute API.
+ let prepared = vmm.prepare_map(pdev, mm, 1, None)?;
+ let mapped2 = vmm.execute_map(pdev, mm, prepared, &[test_pfn], true)?;
+ let readback = vmm.read_mapping(pdev, mm, mapped2.vfn_start)?;
+ let test2_passed = if readback == Some(test_pfn) {
+ true
+ } else {
+ dev_err!(dev, "MM: Test 2 FAILED - Two-phase map readback mismatch\n");
+ false
+ };
+ vmm.unmap_pages(pdev, mm, mapped2)?;
+
+ // Test 3: Range-constrained allocation with a hole — exercises block.size()-driven
+ // BAR1 mapping. A 4K hole is punched at base+16K, then a single 32K allocation
+ // is requested within [base, base+36K). The buddy allocator must split around the
+ // hole, returning multiple blocks (expected: {16K, 4K, 8K, 4K} = 32K total).
+ // Each block is mapped into BAR1 and verified via PRAMIN read-back.
+ //
+ // Address layout (base = 0x10000):
+ // [ 16K ] [HOLE 4K] [4K] [ 8K ] [4K]
+ // 0x10000 0x14000 0x15000 0x16000 0x18000 0x19000
+ let range_base: u64 = SZ_64K.into_safe_cast();
+ let sz_4k: u64 = SZ_4K.into_safe_cast();
+ let sz_16k: u64 = SZ_16K.into_safe_cast();
+ let sz_32k_4k: u64 = (SZ_32K + SZ_4K).into_safe_cast();
+
+ // Punch a 4K hole at base+16K so the subsequent 32K allocation must split.
+ let _hole = KBox::pin_init(
+ mm.buddy().alloc_blocks(
+ GpuBuddyAllocMode::Range(range_base + sz_16k..range_base + sz_16k + sz_4k),
+ SZ_4K.into_safe_cast(),
+ Alignment::new::<SZ_4K>(),
+ GpuBuddyAllocFlags::default(),
+ ),
+ GFP_KERNEL,
+ )?;
+
+ // Allocate 32K within [base, base+36K). The hole forces the allocator to return
+ // split blocks whose sizes are determined by buddy alignment.
+ let blocks = KBox::pin_init(
+ mm.buddy().alloc_blocks(
+ GpuBuddyAllocMode::Range(range_base..range_base + sz_32k_4k),
+ SZ_32K.into_safe_cast(),
+ Alignment::new::<SZ_4K>(),
+ GpuBuddyAllocFlags::default(),
+ ),
+ GFP_KERNEL,
+ )?;
+
+ let mut test3_passed = true;
+ let mut total_size = 0usize;
+
+ for block in blocks.iter() {
+ total_size += IntoSafeCast::<usize>::into_safe_cast(block.size());
+
+ // Map all pages of this block.
+ let page_size: u64 = PAGE_SIZE.into_safe_cast();
+ let num_pages: usize = (block.size() / page_size).into_safe_cast();
+
+ let mut pfns = KVec::new();
+ for j in 0..num_pages {
+ let j_u64: u64 = j.into_safe_cast();
+ pfns.push(
+ Pfn::from(VramAddress::new(
+ block.offset() + j_u64.checked_mul(page_size).ok_or(EOVERFLOW)?,
+ )),
+ GFP_KERNEL,
+ )?;
+ }
+
+ let mapped = vmm.map_pages(pdev, mm, &pfns, None, true)?;
+ let bar1_base_vfn: usize = mapped.vfn_start.raw().into_safe_cast();
+ let bar1_base = bar1_base_vfn.checked_mul(PAGE_SIZE).ok_or(EOVERFLOW)?;
+
+ for j in 0..num_pages {
+ let page_bar1_off = bar1_base + j * PAGE_SIZE;
+ let j_u64: u64 = j.into_safe_cast();
+ let page_phys = block.offset()
+ + j_u64
+ .checked_mul(PAGE_SIZE.into_safe_cast())
+ .ok_or(EOVERFLOW)?;
+
+ bar1.try_write32(PATTERN_BAR1, page_bar1_off)?;
+
+ let pramin_val = {
+ let mut window = mm.pramin().get_window(pdev)?;
+ window.try_read32(page_phys.into_safe_cast())?
+ };
+
+ if pramin_val != PATTERN_BAR1 {
+ dev_err!(
+ dev,
+ "MM: Test 3 FAILED block offset {:#x} page {} (val={:#x})\n",
+ block.offset(),
+ j,
+ pramin_val
+ );
+ test3_passed = false;
+ }
+ }
+
+ vmm.unmap_pages(pdev, mm, mapped)?;
+ }
+
+ // Verify aggregate: all returned block sizes must sum to allocation size.
+ if total_size != SZ_32K {
+ dev_err!(
+ dev,
+ "MM: Test 3 FAILED - total size {} != expected {}\n",
+ total_size,
+ SZ_32K
+ );
+ test3_passed = false;
+ }
+
+ // Release Tests 1-3's Vmm before Test 4 constructs a fresh BarUser on
+ // the same PDB.
+ drop(vmm);
+
+ // Test 4: Exercise `BarUser::map()` end-to-end.
+ let mut bar_user = BarUser::new(pdb_addr, chipset, SZ_64K.into_safe_cast())?;
+ let test4_passed = {
+ let access = bar_user.map(pdev, mm, bar1, &[test_pfn], true)?;
+
+ // Write pattern via PRAMIN, read via BarUserAccess.
+ {
+ let mut window = mm.pramin().get_window(pdev)?;
+ window.try_write32(test_vram.raw(), PATTERN_BAR1)?;
+ }
+
+ let readback = access.try_read32(0)?;
+ if readback == PATTERN_BAR1 {
+ true
+ } else {
+ dev_err!(
+ dev,
+ "MM: Test 4 FAILED - Expected {:#010x}, got {:#010x}\n",
+ PATTERN_BAR1,
+ readback
+ );
+ false
+ }
+ };
+
+ if test1_passed && test2_passed && test3_passed && test4_passed {
+ dev_info!(dev, "MM: All self-tests PASSED\n");
+ Ok(())
+ } else {
+ dev_err!(dev, "MM: Self-tests FAILED\n");
+ Err(EIO)
+ }
+}
diff --git a/drivers/gpu/nova-core/mm/pagetable.rs b/drivers/gpu/nova-core/mm/pagetable.rs
index 4070070922a4..8fd179ce7476 100644
--- a/drivers/gpu/nova-core/mm/pagetable.rs
+++ b/drivers/gpu/nova-core/mm/pagetable.rs
@@ -22,7 +22,10 @@
VirtualAddress,
VramAddress, //
};
-use kernel::prelude::*;
+use kernel::{
+ device,
+ prelude::*, //
+};

/// Extracts the page table index at a given level from a virtual address.
pub(super) trait VaLevelIndex {
@@ -383,3 +386,33 @@ fn from(val: AperturePde) -> Self {
Bounded::from_expr(val as u64 & 0x3)
}
}
+
+/// Check if the PDB has valid, VRAM-backed page tables.
+#[cfg(CONFIG_NOVA_MM_SELFTESTS)]
+fn check_pdb_inner<M: MmuConfig>(
+ dev: &device::Device<device::Bound>,
+ pramin: &pramin::Pramin,
+ pdb_addr: VramAddress,
+) -> Result {
+ let mut window = pramin.get_window(dev)?;
+ let raw = window.try_read64(pdb_addr.raw())?;
+
+ if !M::Pde::new(raw).is_valid_vram() {
+ return Err(ENOENT);
+ }
+ Ok(())
+}
+
+/// Check if the PDB has valid, VRAM-backed page tables, dispatching by MMU version.
+#[cfg(CONFIG_NOVA_MM_SELFTESTS)]
+pub(super) fn check_pdb_valid(
+ dev: &device::Device<device::Bound>,
+ pramin: &pramin::Pramin,
+ pdb_addr: VramAddress,
+ chipset: crate::gpu::Chipset,
+) -> Result {
+ match MmuVersion::from(chipset.arch()) {
+ MmuVersion::V2 => check_pdb_inner::<MmuV2>(dev, pramin, pdb_addr),
+ MmuVersion::V3 => check_pdb_inner::<MmuV3>(dev, pramin, pdb_addr),
+ }
+}
--
2.34.1