[PATCH v8 24/25] gpu: nova-core: mm: Add BAR1 memory management self-tests

[Joel Fernandes]

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@xxxxxxxxxx>
Signed-off-by: Joel Fernandes <joelagnelf@xxxxxxxxxx>
---
 drivers/gpu/nova-core/Kconfig        |  10 ++
 drivers/gpu/nova-core/driver.rs      |   2 +
 drivers/gpu/nova-core/gpu.rs         |  42 +++++
 drivers/gpu/nova-core/mm/bar_user.rs | 250 +++++++++++++++++++++++++++
 4 files changed, 304 insertions(+)

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 d8b2e967ba4c..7d0d09939835 100644
--- a/drivers/gpu/nova-core/driver.rs
+++ b/drivers/gpu/nova-core/driver.rs
@@ -92,6 +92,8 @@ 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 4281487ca52e..fba6ddba6a3f 100644
--- a/drivers/gpu/nova-core/gpu.rs
+++ b/drivers/gpu/nova-core/gpu.rs
@@ -380,4 +380,46 @@ 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(mut self: Pin<&mut Self>, pdev: &pci::Device<device::Bound>) -> Result {
+        use crate::driver::BAR1_SIZE;
+
+        let mmu_version = MmuVersion::from(self.spec.chipset.arch());
+
+        // BAR1 self-tests.
+        let bar1 = Arc::pin_init(
+            pdev.iomap_region_sized::<BAR1_SIZE>(1, c"nova-core/bar1"),
+            GFP_KERNEL,
+        )?;
+        let bar1_access = bar1.access(pdev.as_ref())?;
+
+        let proj = self.as_mut().project();
+        let bar1_pde_base = proj.gsp_static_info.bar1_pde_base();
+        let mm = proj.mm.as_ref().get_ref();
+
+        crate::mm::bar_user::run_self_test(
+            pdev.as_ref(),
+            mm,
+            bar1_access,
+            bar1_pde_base,
+            mmu_version,
+        )?;
+
+        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 4af56ac628b6..28dfb10e7cea 100644
--- a/drivers/gpu/nova-core/mm/bar_user.rs
+++ b/drivers/gpu/nova-core/mm/bar_user.rs
@@ -154,3 +154,253 @@ fn drop(&mut self) {
         }
     }
 }
+
+/// Check if the PDB has valid, VRAM-backed page tables.
+///
+/// Returns `Err(ENOENT)` if page tables are missing or not in VRAM.
+#[cfg(CONFIG_NOVA_MM_SELFTESTS)]
+fn check_valid_page_tables(mm: &GpuMm, pdb_addr: VramAddress) -> Result {
+    use crate::mm::pagetable::{
+        ver2::Pde,
+        AperturePde, //
+    };
+
+    let mut window = mm.pramin().window()?;
+    let pdb_entry_raw = window.try_read64(pdb_addr.raw())?;
+    let pdb_entry = Pde::new(pdb_entry_raw);
+
+    if !pdb_entry.is_valid() {
+        return Err(ENOENT);
+    }
+
+    if pdb_entry.aperture() != AperturePde::VideoMemory {
+        return Err(ENOENT);
+    }
+
+    Ok(())
+}
+
+/// 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(
+    dev: &kernel::device::Device,
+    mm: &GpuMm,
+    bar1: &crate::driver::Bar1,
+    bar1_pdb: u64,
+    mmu_version: MmuVersion,
+) -> Result {
+    use crate::mm::{
+        vmm::Vmm,
+        PAGE_SIZE, //
+    };
+    use kernel::gpu::buddy::{
+        BuddyFlags,
+        GpuBuddyAllocParams, //
+    };
+    use kernel::sizes::{
+        SZ_4K,
+        SZ_16K,
+        SZ_32K,
+        SZ_64K, //
+    };
+
+    // Self-tests only support MMU v2 for now.
+    if mmu_version != MmuVersion::V2 {
+        dev_info!(
+            dev,
+            "MM: Skipping self-tests for MMU {:?} (only V2 supported)\n",
+            mmu_version
+        );
+        return Ok(());
+    }
+
+    // Test patterns.
+    const PATTERN_PRAMIN: u32 = 0xDEAD_BEEF;
+    const PATTERN_BAR1: u32 = 0xCAFE_BABE;
+
+    dev_info!(dev, "MM: Starting self-test...\n");
+
+    let pdb_addr = VramAddress::new(bar1_pdb);
+
+    // Check if initial page tables are in VRAM.
+    if check_valid_page_tables(mm, pdb_addr).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 alloc_params = GpuBuddyAllocParams {
+        start_range_address: 0,
+        end_range_address: 0,
+        size_bytes: SZ_4K.into_safe_cast(),
+        min_block_size_bytes: SZ_4K.into_safe_cast(),
+        buddy_flags: BuddyFlags::try_new(0)?,
+    };
+
+    let test_page_blocks = KBox::pin_init(mm.buddy().alloc_blocks(&alloc_params), 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, MmuVersion::V2, SZ_64K.into_safe_cast())?;
+
+    // Create a test mapping.
+    let mapped = vmm.map_pages(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().window()?;
+        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(mm, mapped)?;
+
+    // Test 2: Two-phase prepare/execute API.
+    let prepared = vmm.prepare_map(mm, 1, None)?;
+    let mapped2 = vmm.execute_map(mm, prepared, &[test_pfn], true)?;
+    let readback = vmm.read_mapping(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(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 range_flag = BuddyFlags::try_new(BuddyFlags::RANGE_ALLOCATION)?;
+    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(&GpuBuddyAllocParams {
+        start_range_address: range_base + sz_16k,
+        end_range_address: range_base + sz_16k + sz_4k,
+        size_bytes: SZ_4K.into_safe_cast(),
+        min_block_size_bytes: SZ_4K.into_safe_cast(),
+        buddy_flags: range_flag,
+    }), 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(&GpuBuddyAllocParams {
+        start_range_address: range_base,
+        end_range_address: range_base + sz_32k_4k,
+        size_bytes: SZ_32K.into_safe_cast(),
+        min_block_size_bytes: SZ_4K.into_safe_cast(),
+        buddy_flags: range_flag,
+    }), GFP_KERNEL)?;
+
+    let mut test3_passed = true;
+    let mut total_size = 0u64;
+
+    for block in blocks.iter() {
+        total_size += 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(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().window()?;
+                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(mm, mapped)?;
+    }
+
+    // Verify aggregate: all returned block sizes must sum to allocation size.
+    if total_size != SZ_32K.into_safe_cast() {
+        dev_err!(
+            dev,
+            "MM: Test 3 FAILED - total size {} != expected {}\n",
+            total_size,
+            SZ_32K
+        );
+        test3_passed = false;
+    }
+
+    if test1_passed && test2_passed && test3_passed {
+        dev_info!(dev, "MM: All self-tests PASSED\n");
+        Ok(())
+    } else {
+        dev_err!(dev, "MM: Self-tests FAILED\n");
+        Err(EIO)
+    }
+}
-- 
2.34.1