Add the page table mapping and unmapping API to the Virtual Memory Manager, implementing a two-phase prepare/execute model suitable for use both inside and outside the DMA fence signalling critical path.
Signed-off-by: Joel Fernandes <[email protected]> --- drivers/gpu/nova-core/mm/pagetable.rs | 1 + drivers/gpu/nova-core/mm/pagetable/map.rs | 367 ++++++++++++++++++++++ drivers/gpu/nova-core/mm/vmm.rs | 270 ++++++++++++++-- 3 files changed, 619 insertions(+), 19 deletions(-) create mode 100644 drivers/gpu/nova-core/mm/pagetable/map.rs diff --git a/drivers/gpu/nova-core/mm/pagetable.rs b/drivers/gpu/nova-core/mm/pagetable.rs index 5e192679f27c..042584e5178b 100644 --- a/drivers/gpu/nova-core/mm/pagetable.rs +++ b/drivers/gpu/nova-core/mm/pagetable.rs @@ -8,6 +8,7 @@ #![expect(dead_code)] +pub(super) mod map; pub(super) mod ver2; pub(super) mod ver3; pub(super) mod walk; diff --git a/drivers/gpu/nova-core/mm/pagetable/map.rs b/drivers/gpu/nova-core/mm/pagetable/map.rs new file mode 100644 index 000000000000..b0678a36d406 --- /dev/null +++ b/drivers/gpu/nova-core/mm/pagetable/map.rs @@ -0,0 +1,367 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Page table mapping operations for NVIDIA GPUs. + +use core::marker::PhantomData; + +use kernel::{ + device, + gpu::buddy::{ + AllocatedBlocks, + GpuBuddyAllocFlags, + GpuBuddyAllocMode, // + }, + prelude::*, + ptr::Alignment, + rbtree::{RBTree, RBTreeNode}, + sizes::SZ_4K, // +}; + +use super::{ + walk::{ + PtWalkInner, + WalkPdeResult, + WalkResult, // + }, + AperturePde, + AperturePte, + DualPdeOps, + MmuConfig, + MmuV2, + MmuV3, + MmuVersion, + PageTableLevel, + PdeOps, + PteOps, // +}; +use crate::{ + mm::{ + GpuMm, + Pfn, + Vfn, + VramAddress, + PAGE_SIZE, // + }, + num::{ + IntoSafeCast, // + }, +}; + +/// A pre-allocated and zeroed page table page. +/// +/// Created during the mapping prepare phase and consumed during the execute phase. +/// Stored in an [`RBTree`] keyed by the PDE slot address (`install_addr`). +pub(in crate::mm) struct PreparedPtPage { + /// The allocated and zeroed page table page. + pub(in crate::mm) alloc: Pin<KBox<AllocatedBlocks>>, + /// Page table level -- needed to determine if this PT page is for a dual PDE. + pub(in crate::mm) level: PageTableLevel, +} + +/// Page table mapper. +pub(in crate::mm) struct PtMapInner<M: MmuConfig> { + walker: PtWalkInner<M>, + pdb_addr: VramAddress, + _phantom: PhantomData<M>, +} + +impl<M: MmuConfig> PtMapInner<M> { + /// Create a new [`PtMapInner`]. + pub(super) fn new(pdb_addr: VramAddress) -> Self { + Self { + walker: PtWalkInner::<M>::new(pdb_addr), + pdb_addr, + _phantom: PhantomData, + } + } + + /// Allocate and zero a physical page table page. + fn alloc_and_zero_page( + dev: &device::Device<device::Bound>, + mm: &GpuMm, + level: PageTableLevel, + ) -> Result<PreparedPtPage> { + let blocks = KBox::pin_init( + mm.buddy().alloc_blocks( + GpuBuddyAllocMode::Simple, + SZ_4K.into_safe_cast(), + Alignment::new::<SZ_4K>(), + GpuBuddyAllocFlags::default(), + ), + GFP_KERNEL, + )?; + + let page_vram = VramAddress::new(blocks.iter().next().ok_or(ENOMEM)?.offset()); + + // Zero via PRAMIN. + let mut window = mm.pramin().get_window(dev)?; + for off in (0..PAGE_SIZE).step_by(8) { + let off_u64: u64 = off.into_safe_cast(); + window.try_write64(page_vram + off_u64, 0)?; + } + + Ok(PreparedPtPage { + alloc: blocks, + level, + }) + } + + /// Ensure all intermediate page table pages exist for a single VFN. + /// + /// PRAMIN is released before each allocation and re-acquired after. Memory + /// allocations are done outside of holding this lock to prevent deadlocks with + /// the fence signalling critical path. + fn ensure_single_pte_path( + &self, + dev: &device::Device<device::Bound>, + mm: &GpuMm, + vfn: Vfn, + pt_pages: &mut RBTree<VramAddress, PreparedPtPage>, + ) -> Result { + let max_iter = 2 * M::PDE_LEVELS.len(); + + for _ in 0..max_iter { + let mut window = mm.pramin().get_window(dev)?; + + let result = self + .walker + .walk_pde_levels(&mut window, vfn, |install_addr| { + pt_pages + .get(&install_addr) + .and_then(|p| p.alloc.iter().next().map(|b| VramAddress::new(b.offset()))) + })?; + + match result { + WalkPdeResult::Complete { .. } => { + return Ok(()); + } + WalkPdeResult::Missing { + install_addr, + level, + } => { + // Drop PRAMIN before allocation. + drop(window); + let page = Self::alloc_and_zero_page(dev, mm, level)?; + let node = RBTreeNode::new(install_addr, page, GFP_KERNEL)?; + let old = pt_pages.insert(node); + if old.is_some() { + kernel::pr_warn_once!( + "VMM: duplicate install_addr in pt_pages (internal consistency error)\n" + ); + return Err(EIO); + } + } + } + } + + kernel::pr_warn!( + "VMM: ensure_pte_path: loop exhausted after {} iters (VFN {:?})\n", + max_iter, + vfn + ); + Err(EIO) + } + + /// Prepare page table resources for mapping `num_pages` pages starting at `vfn_start`. + /// + /// Reserves capacity in `page_table_allocs`, then walks the hierarchy + /// per-VFN to prepare pages for all missing PDEs. + pub(super) fn prepare_map( + &self, + dev: &device::Device<device::Bound>, + mm: &GpuMm, + vfn_start: Vfn, + num_pages: usize, + page_table_allocs: &mut KVec<Pin<KBox<AllocatedBlocks>>>, + pt_pages: &mut RBTree<VramAddress, PreparedPtPage>, + ) -> Result { + // Pre-reserve so install_mappings() can use push_within_capacity (no alloc + // in fence signalling critical path). + let pt_upper_bound = M::pt_pages_upper_bound(num_pages); + page_table_allocs.reserve(pt_upper_bound, GFP_KERNEL)?; + + // Walk the hierarchy per-VFN to prepare pages for all missing PDEs. + for i in 0..num_pages { + let i_u64: u64 = i.into_safe_cast(); + let vfn = Vfn::new(vfn_start.raw() + i_u64); + self.ensure_single_pte_path(dev, mm, vfn, pt_pages)?; + } + Ok(()) + } + + /// Install prepared PDEs and write PTEs, then flush TLB. + /// + /// Drains `pt_pages` and moves allocations into `page_table_allocs`. + #[expect(clippy::too_many_arguments)] + pub(super) fn install_mappings( + &self, + dev: &device::Device<device::Bound>, + mm: &GpuMm, + pt_pages: &mut RBTree<VramAddress, PreparedPtPage>, + page_table_allocs: &mut KVec<Pin<KBox<AllocatedBlocks>>>, + vfn_start: Vfn, + pfns: &[Pfn], + writable: bool, + ) -> Result { + let mut window = mm.pramin().get_window(dev)?; + + // Drain prepared PT pages, install all pending PDEs. + let mut cursor = pt_pages.cursor_front_mut(); + while let Some(c) = cursor { + let (next, node) = c.remove_current(); + let (install_addr, page) = node.to_key_value(); + let page_vram = VramAddress::new(page.alloc.iter().next().ok_or(ENOMEM)?.offset()); + + if page.level == M::DUAL_PDE_LEVEL { + let new_dpde = M::DualPde::new_small(Pfn::from(page_vram)); + new_dpde.write(&mut window, install_addr)?; + } else { + let new_pde = M::Pde::new(AperturePde::VideoMemory, Pfn::from(page_vram)); + new_pde.write(&mut window, install_addr)?; + } + + page_table_allocs + .push_within_capacity(page.alloc) + .map_err(|_| ENOMEM)?; + + cursor = next; + } + + // Write PTEs (all PDEs now installed in HW). + for (i, &pfn) in pfns.iter().enumerate() { + let i_u64: u64 = i.into_safe_cast(); + let vfn = Vfn::new(vfn_start.raw() + i_u64); + let result = self + .walker + .walk_to_pte_lookup_with_window(&mut window, vfn)?; + + match result { + WalkResult::Unmapped { pte_addr } | WalkResult::Mapped { pte_addr, .. } => { + let pte = M::Pte::new(AperturePte::VideoMemory, pfn, writable); + pte.write(&mut window, pte_addr)?; + } + WalkResult::PageTableMissing => { + kernel::pr_warn_once!("VMM: page table missing for VFN {vfn:?}\n"); + return Err(EIO); + } + } + } + + drop(window); + + // Flush TLB. + mm.tlb().flush(dev, self.pdb_addr) + } + + /// Invalidate PTEs for a range and flush TLB. + pub(super) fn invalidate_ptes( + &self, + dev: &device::Device<device::Bound>, + mm: &GpuMm, + vfn_start: Vfn, + num_pages: usize, + ) -> Result { + let invalid_pte = M::Pte::invalid(); + + let mut window = mm.pramin().get_window(dev)?; + for i in 0..num_pages { + let i_u64: u64 = i.into_safe_cast(); + let vfn = Vfn::new(vfn_start.raw() + i_u64); + let result = self + .walker + .walk_to_pte_lookup_with_window(&mut window, vfn)?; + + match result { + WalkResult::Mapped { pte_addr, .. } | WalkResult::Unmapped { pte_addr } => { + invalid_pte.write(&mut window, pte_addr)?; + } + WalkResult::PageTableMissing => { + continue; + } + } + } + drop(window); + + mm.tlb().flush(dev, self.pdb_addr) + } +} + +macro_rules! pt_map_dispatch { + ($self:expr, $method:ident ( $($arg:expr),* $(,)? )) => { + match $self { + PtMap::V2(inner) => inner.$method($($arg),*), + PtMap::V3(inner) => inner.$method($($arg),*), + } + }; +} + +/// Page table mapper dispatch. +pub(in crate::mm) enum PtMap { + /// MMU v2 (Turing/Ampere/Ada). + V2(PtMapInner<MmuV2>), + /// MMU v3 (Hopper+). + V3(PtMapInner<MmuV3>), +} + +impl PtMap { + /// Create a new page table mapper for the given MMU version. + pub(in crate::mm) fn new(pdb_addr: VramAddress, version: MmuVersion) -> Self { + match version { + MmuVersion::V2 => Self::V2(PtMapInner::<MmuV2>::new(pdb_addr)), + MmuVersion::V3 => Self::V3(PtMapInner::<MmuV3>::new(pdb_addr)), + } + } + + /// Prepare page table resources for a mapping. + pub(in crate::mm) fn prepare_map( + &self, + dev: &device::Device<device::Bound>, + mm: &GpuMm, + vfn_start: Vfn, + num_pages: usize, + page_table_allocs: &mut KVec<Pin<KBox<AllocatedBlocks>>>, + pt_pages: &mut RBTree<VramAddress, PreparedPtPage>, + ) -> Result { + pt_map_dispatch!( + self, + prepare_map(dev, mm, vfn_start, num_pages, page_table_allocs, pt_pages) + ) + } + + /// Install prepared PDEs and write PTEs, then flush TLB. + #[expect(clippy::too_many_arguments)] + pub(in crate::mm) fn install_mappings( + &self, + dev: &device::Device<device::Bound>, + mm: &GpuMm, + pt_pages: &mut RBTree<VramAddress, PreparedPtPage>, + page_table_allocs: &mut KVec<Pin<KBox<AllocatedBlocks>>>, + vfn_start: Vfn, + pfns: &[Pfn], + writable: bool, + ) -> Result { + pt_map_dispatch!( + self, + install_mappings( + dev, + mm, + pt_pages, + page_table_allocs, + vfn_start, + pfns, + writable + ) + ) + } + + /// Invalidate PTEs for a range and flush TLB. + pub(in crate::mm) fn invalidate_ptes( + &self, + dev: &device::Device<device::Bound>, + mm: &GpuMm, + vfn_start: Vfn, + num_pages: usize, + ) -> Result { + pt_map_dispatch!(self, invalidate_ptes(dev, mm, vfn_start, num_pages)) + } +} diff --git a/drivers/gpu/nova-core/mm/vmm.rs b/drivers/gpu/nova-core/mm/vmm.rs index 05ff77c5f888..1cceea759f6a 100644 --- a/drivers/gpu/nova-core/mm/vmm.rs +++ b/drivers/gpu/nova-core/mm/vmm.rs @@ -3,22 +3,31 @@ //! Virtual Memory Manager for NVIDIA GPU page table management. //! //! The [`Vmm`] provides high-level page mapping and unmapping operations for GPU -//! virtual address spaces (Channels, BAR1, BAR2). It wraps the page table walker -//! and handles TLB flushing after modifications. +//! virtual address spaces (Channels, BAR1, BAR2). use kernel::{ device, gpu::buddy::AllocatedBlocks, maple_tree::MapleTreeAlloc, - prelude::*, // + prelude::*, + rbtree::RBTree, // }; -use core::ops::Range; +use core::{ + cell::Cell, + ops::Range, // +}; use crate::{ mm::{ pagetable::{ - walk::{PtWalk, WalkResult}, + map::{ + PtMap, // + }, + walk::{ + PtWalk, + WalkResult, // + }, MmuVersion, // }, GpuMm, @@ -32,22 +41,108 @@ }, }; +/// Multi-page prepared mapping -- VA range allocated, ready for execute. +/// +/// Produced by [`Vmm::prepare_map()`], consumed by [`Vmm::execute_map()`]. +/// The VA space allocation is tracked in the [`Vmm`]'s maple tree and freed +/// on error or via [`Vmm::unmap_pages()`]. +/// +/// Dropping without calling [`Vmm::execute_map()`] logs a warning and leaks +/// the VA range in the maple tree. +pub(crate) struct PreparedMapping { + vfn_start: Vfn, + num_pages: usize, + /// Logs a warning if dropped without executing. + _drop_guard: MustExecuteGuard, +} + +/// Result of a mapping operation -- tracks the active mapped range. +/// +/// Returned by [`Vmm::execute_map()`] and [`Vmm::map_pages()`]. +/// Callers must call [`Vmm::unmap_pages()`] before dropping to invalidate +/// PTEs and free the VA range. Dropping without unmapping logs a warning +/// and leaks the VA range in the maple tree. +pub(crate) struct MappedRange { + pub(super) vfn_start: Vfn, + pub(super) num_pages: usize, + /// Logs a warning if dropped without unmapping. + _drop_guard: MustUnmapGuard, +} + +/// Guard that logs a warning if a [`PreparedMapping`] is dropped without +/// being consumed by [`Vmm::execute_map()`]. +struct MustExecuteGuard { + armed: Cell<bool>, +} + +impl MustExecuteGuard { + const fn new() -> Self { + Self { + armed: Cell::new(true), + } + } + + fn disarm(&self) { + self.armed.set(false); + } +} + +impl Drop for MustExecuteGuard { + fn drop(&mut self) { + if self.armed.get() { + kernel::pr_warn!("PreparedMapping dropped without calling execute_map()\n"); + } + } +} + +/// Guard that logs a warning if a [`MappedRange`] is dropped without +/// calling [`Vmm::unmap_pages()`]. +struct MustUnmapGuard { + armed: Cell<bool>, +} + +impl MustUnmapGuard { + const fn new() -> Self { + Self { + armed: Cell::new(true), + } + } + + fn disarm(&self) { + self.armed.set(false); + } +} + +impl Drop for MustUnmapGuard { + fn drop(&mut self) { + if self.armed.get() { + kernel::pr_warn!("MappedRange dropped without calling unmap_pages()\n"); + } + } +} + /// Virtual Memory Manager for a GPU address space. /// /// Each [`Vmm`] instance manages a single address space identified by its Page -/// Directory Base (`PDB`) address. The [`Vmm`] is used for Channel, BAR1 and -/// BAR2 mappings. +/// Directory Base (`PDB`) address. Used for Channel, BAR1 and BAR2 mappings. pub(crate) struct Vmm { /// Page Directory Base address for this address space. pdb_addr: VramAddress, - /// MMU version used for page table layout. - mmu_version: MmuVersion, + /// Page table walker for reading existing mappings. + pt_walk: PtWalk, + /// Page table mapper for prepare/execute operations. + pt_map: PtMap, /// Page table allocations required for mappings. page_table_allocs: KVec<Pin<KBox<AllocatedBlocks>>>, /// Maple tree allocator for virtual address range tracking. virt_alloc: Pin<KBox<MapleTreeAlloc<()>>>, /// Total number of pages in the virtual address space. va_pages: usize, + /// Prepared PT pages pending PDE installation, keyed by `install_addr`. + /// + /// Populated during prepare phase and drained in execute phase. Shared by all + /// pending maps, preventing races on the same PDE slot. + pt_pages: RBTree<VramAddress, super::pagetable::map::PreparedPtPage>, } impl Vmm { @@ -65,20 +160,16 @@ pub(crate) fn new( Ok(Self { pdb_addr, - mmu_version, + pt_walk: PtWalk::new(pdb_addr, mmu_version), + pt_map: PtMap::new(pdb_addr, mmu_version), page_table_allocs: KVec::new(), virt_alloc, va_pages, + pt_pages: RBTree::new(), }) } /// Allocate a contiguous virtual frame number range. - /// - /// # Arguments - /// - /// - `num_pages`: Number of pages to allocate. - /// - `va_range`: `None` = allocate anywhere, `Some(range)` = constrain allocation to the given - /// range. fn alloc_vfn_range(&self, num_pages: usize, va_range: Option<Range<u64>>) -> Result<Vfn> { let page_size: u64 = PAGE_SIZE.into_safe_cast(); @@ -119,11 +210,152 @@ pub(super) fn read_mapping( mm: &GpuMm, vfn: Vfn, ) -> Result<Option<Pfn>> { - let walker = PtWalk::new(self.pdb_addr, self.mmu_version); - - match walker.walk_to_pte(dev, mm, vfn)? { + match self.pt_walk.walk_to_pte(dev, mm, vfn)? { WalkResult::Mapped { pfn, .. } => Ok(Some(pfn)), WalkResult::Unmapped { .. } | WalkResult::PageTableMissing => Ok(None), } } + + /// Prepare resources for mapping `num_pages` pages. + /// + /// Allocates a contiguous VA range, then walks the hierarchy per-VFN to prepare pages + /// for all missing PDEs. Returns a [`PreparedMapping`] with the VA allocation. + /// + /// If `va_range` is not `None`, the VA range is constrained to the given range. Safe + /// to call outside the fence signalling critical path. + pub(crate) fn prepare_map( + &mut self, + dev: &device::Device<device::Bound>, + mm: &GpuMm, + num_pages: usize, + va_range: Option<Range<u64>>, + ) -> Result<PreparedMapping> { + if num_pages == 0 { + return Err(EINVAL); + } + + // Allocate contiguous VA range. + let vfn_start = self.alloc_vfn_range(num_pages, va_range)?; + + if let Err(e) = self.pt_map.prepare_map( + dev, + mm, + vfn_start, + num_pages, + &mut self.page_table_allocs, + &mut self.pt_pages, + ) { + self.free_vfn(vfn_start); + return Err(e); + } + + Ok(PreparedMapping { + vfn_start, + num_pages, + _drop_guard: MustExecuteGuard::new(), + }) + } + + /// Execute a prepared multi-page mapping. + /// + /// Installs all prepared PDEs and writes PTEs into the page table, then flushes TLB. + pub(crate) fn execute_map( + &mut self, + dev: &device::Device<device::Bound>, + mm: &GpuMm, + prepared: PreparedMapping, + pfns: &[Pfn], + writable: bool, + ) -> Result<MappedRange> { + if pfns.len() != prepared.num_pages { + self.free_vfn(prepared.vfn_start); + return Err(EINVAL); + } + + let PreparedMapping { + vfn_start, + num_pages, + _drop_guard, + } = prepared; + _drop_guard.disarm(); + + if let Err(e) = self.pt_map.install_mappings( + dev, + mm, + &mut self.pt_pages, + &mut self.page_table_allocs, + vfn_start, + pfns, + writable, + ) { + self.free_vfn(vfn_start); + return Err(e); + } + + Ok(MappedRange { + vfn_start, + num_pages, + _drop_guard: MustUnmapGuard::new(), + }) + } + + /// Map pages doing prepare and execute in the same call. + /// + /// This is a convenience wrapper for callers outside the fence signalling critical + /// path (e.g., BAR mappings). For DRM usecases, [`Vmm::prepare_map()`] and + /// [`Vmm::execute_map()`] will be called separately. + pub(crate) fn map_pages( + &mut self, + dev: &device::Device<device::Bound>, + mm: &GpuMm, + pfns: &[Pfn], + va_range: Option<Range<u64>>, + writable: bool, + ) -> Result<MappedRange> { + if pfns.is_empty() { + return Err(EINVAL); + } + + // Check if provided VA range is sufficient (if provided). + if let Some(ref range) = va_range { + let required: u64 = pfns + .len() + .checked_mul(PAGE_SIZE) + .ok_or(EOVERFLOW)? + .into_safe_cast(); + let available = range.end.checked_sub(range.start).ok_or(EINVAL)?; + if available < required { + return Err(EINVAL); + } + } + + let prepared = self.prepare_map(dev, mm, pfns.len(), va_range)?; + self.execute_map(dev, mm, prepared, pfns, writable) + } + + /// Unmap all pages in a [`MappedRange`] with a single TLB flush. + pub(crate) fn unmap_pages( + &mut self, + dev: &device::Device<device::Bound>, + mm: &GpuMm, + range: MappedRange, + ) -> Result { + let result = self + .pt_map + .invalidate_ptes(dev, mm, range.vfn_start, range.num_pages); + + // TODO: Internal page table pages (PDE, PTE pages) are still kept around. + // This is by design as repeated maps/unmaps will be fast. As a future TODO, + // we can add a reclaimer here to reclaim if VRAM is short. For now, the PT + // pages are dropped once the `Vmm` is dropped. + + // Free the VA range regardless of PTE invalidation success, so that the VA + // range is recovered even on failure (PTEs may be stale, but that is better + // than leaking both PTEs and VA range). + self.free_vfn(range.vfn_start); + + // Unmap complete, safe to drop `MappedRange`. + range._drop_guard.disarm(); + result + } } -- 2.34.1
