resources+pci: allocator rework (allocation tags)

AddressAllocator now maintains a HashMap<Alloc, (u64, u64, u64)>,
which uniquely maps a Allocation enum (e.g: PciBar(bus, dev, bar),
GpuRenderNode, etc...) to it's address, size, and human-readable tag
/ description.

The interface has also been modified to use Error instead of Option.

Aside from improving debugging, tracking allocations will have
numerous uses in the future. For example, when allocating guest memory
over VmControl sockets, it will be possible to restrict allocations to
pre-allocated slices of memory owned by the requesting device.

To plumb through PCI information to PCI devices, this CL necessitated
the addition of a PciDevice method called `assign_bus_dev`, which
notifies PCI devices of their uniquely assigned Bus and Device numbers.

BUG=chromium:936567
TEST=cargo test -p resources && cargo build --features="gpu gpu-forward"

Change-Id: I8b4b0e32c6f3168138739249ede53d03143ee5c3
Reviewed-on: https://chromium-review.googlesource.com/1536207
Commit-Ready: Daniel Prilik <prilik@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Zach Reizner <zachr@chromium.org>

1 files changed, 97 insertions, 25 deletions

diff --git a/resources/src/address_allocator.rs b/resources/src/address_allocator.rs
index 6c8513d..45927e0 100644
--- a/resources/src/address_allocator.rs
+++ b/resources/src/address_allocator.rs
@@ -2,16 +2,25 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+use std::collections::HashMap;
+
+use crate::{Alloc, Error, Result};
+
 /// Manages allocating address ranges.
 /// Use `AddressAllocator` whenever an address range needs to be allocated to different users.
+/// Allocations must be uniquely tagged with an Alloc enum, which can be used for lookup.
+/// An human-readable tag String must also be provided for debugging / reference.
 ///
 /// # Examples
 ///
 /// ```
-/// # use resources::AddressAllocator;
+/// // Anon is used for brevity. Don't manually instantiate Anon allocs!
+/// # use resources::{Alloc, AddressAllocator};
 ///   AddressAllocator::new(0x1000, 0x10000, Some(0x100)).map(|mut pool| {
-///       assert_eq!(pool.allocate(0x110), Some(0x1000));
-///       assert_eq!(pool.allocate(0x100), Some(0x1200));
+///       assert_eq!(pool.allocate(0x110, Alloc::Anon(0), "caps".to_string()), Ok(0x1000));
+///       assert_eq!(pool.allocate(0x100, Alloc::Anon(1), "cache".to_string()), Ok(0x1200));
+///       assert_eq!(pool.allocate(0x100, Alloc::Anon(2), "etc".to_string()), Ok(0x1300));
+///       assert_eq!(pool.get(&Alloc::Anon(1)), Some(&(0x1200, 0x100, "cache".to_string())));
 ///   });
 /// ```
 #[derive(Debug, Eq, PartialEq)]
@@ -20,6 +29,7 @@ pub struct AddressAllocator {
     pool_end: u64,
     alignment: u64,
     next_addr: u64,
+    allocs: HashMap<Alloc, (u64, u64, String)>,
 }
 
 impl AddressAllocator {
@@ -30,43 +40,64 @@ impl AddressAllocator {
     /// * `pool_base` - The starting address of the range to manage.
     /// * `pool_size` - The size of the address range in bytes.
     /// * `align_size` - The minimum size of an address region to align to, defaults to four.
-    pub fn new(pool_base: u64, pool_size: u64, align_size: Option<u64>) -> Option<Self> {
+    pub fn new(pool_base: u64, pool_size: u64, align_size: Option<u64>) -> Result<Self> {
         if pool_size == 0 {
-            return None;
+            return Err(Error::PoolSizeZero);
         }
-        let pool_end = pool_base.checked_add(pool_size - 1)?;
+        let pool_end = pool_base
+            .checked_add(pool_size - 1)
+            .ok_or(Error::PoolOverflow {
+                base: pool_base,
+                size: pool_size,
+            })?;
         let alignment = align_size.unwrap_or(4);
         if !alignment.is_power_of_two() || alignment == 0 {
-            return None;
+            return Err(Error::BadAlignment);
         }
-        Some(AddressAllocator {
+        Ok(AddressAllocator {
             pool_base,
             pool_end,
             alignment,
             next_addr: pool_base,
+            allocs: HashMap::new(),
         })
     }
 
-    /// Allocates a range of addresses from the managed region. Returns `Some(allocated_address)`
-    /// when successful, or `None` if an area of `size` can't be allocated.
-    pub fn allocate(&mut self, size: u64) -> Option<u64> {
+    /// Allocates a range of addresses from the managed region with an optional tag.
+    /// Returns allocated_address. (allocated_address, size, tag) can be retrieved
+    /// through the `get` method.
+    pub fn allocate(&mut self, size: u64, alloc: Alloc, tag: String) -> Result<u64> {
+        if self.allocs.contains_key(&alloc) {
+            return Err(Error::ExistingAlloc(alloc));
+        }
         if size == 0 {
-            return None;
+            return Err(Error::AllocSizeZero);
         }
         let align_adjust = if self.next_addr % self.alignment != 0 {
             self.alignment - (self.next_addr % self.alignment)
         } else {
             0
         };
-        let addr = self.next_addr.checked_add(align_adjust)?;
-        let end_addr = addr.checked_add(size - 1)?;
+        let addr = self
+            .next_addr
+            .checked_add(align_adjust)
+            .ok_or(Error::OutOfSpace)?;
+        let end_addr = addr.checked_add(size - 1).ok_or(Error::OutOfSpace)?;
         if end_addr > self.pool_end {
-            return None;
+            return Err(Error::OutOfSpace);
         }
+
         // TODO(dgreid): Use a smarter allocation strategy. The current strategy is just
         // bumping this pointer, meaning it will eventually exhaust available addresses.
         self.next_addr = end_addr.saturating_add(1);
-        Some(addr)
+
+        self.allocs.insert(alloc, (addr, size, tag));
+        Ok(addr)
+    }
+
+    /// Returns allocation associated with `alloc`, or None if no such allocation exists.
+    pub fn get(&self, alloc: &Alloc) -> Option<&(u64, u64, String)> {
+        self.allocs.get(alloc)
     }
 }
 
@@ -76,36 +107,77 @@ mod tests {
 
     #[test]
     fn new_fails_overflow() {
-        assert_eq!(AddressAllocator::new(u64::max_value(), 0x100, None), None);
+        assert!(AddressAllocator::new(u64::max_value(), 0x100, None).is_err());
     }
 
     #[test]
     fn new_fails_size_zero() {
-        assert_eq!(AddressAllocator::new(0x1000, 0, None), None);
+        assert!(AddressAllocator::new(0x1000, 0, None).is_err());
     }
 
     #[test]
     fn new_fails_alignment_zero() {
-        assert_eq!(AddressAllocator::new(0x1000, 0x10000, Some(0)), None);
+        assert!(AddressAllocator::new(0x1000, 0x10000, Some(0)).is_err());
     }
 
     #[test]
     fn new_fails_alignment_non_power_of_two() {
-        assert_eq!(AddressAllocator::new(0x1000, 0x10000, Some(200)), None);
+        assert!(AddressAllocator::new(0x1000, 0x10000, Some(200)).is_err());
+    }
+
+    #[test]
+    fn allocate_fails_exising_alloc() {
+        let mut pool = AddressAllocator::new(0x1000, 0x1000, Some(0x100)).unwrap();
+        assert_eq!(
+            pool.allocate(0x800, Alloc::Anon(0), String::from("bar0")),
+            Ok(0x1000)
+        );
+        assert_eq!(
+            pool.allocate(0x800, Alloc::Anon(0), String::from("bar0")),
+            Err(Error::ExistingAlloc(Alloc::Anon(0)))
+        );
     }
 
     #[test]
     fn allocate_fails_not_enough_space() {
         let mut pool = AddressAllocator::new(0x1000, 0x1000, Some(0x100)).unwrap();
-        assert_eq!(pool.allocate(0x800), Some(0x1000));
-        assert_eq!(pool.allocate(0x900), None);
-        assert_eq!(pool.allocate(0x800), Some(0x1800));
+        assert_eq!(
+            pool.allocate(0x800, Alloc::Anon(0), String::from("bar0")),
+            Ok(0x1000)
+        );
+        assert_eq!(
+            pool.allocate(0x900, Alloc::Anon(1), String::from("bar1")),
+            Err(Error::OutOfSpace)
+        );
+        assert_eq!(
+            pool.allocate(0x800, Alloc::Anon(2), String::from("bar2")),
+            Ok(0x1800)
+        );
     }
 
     #[test]
     fn allocate_alignment() {
         let mut pool = AddressAllocator::new(0x1000, 0x10000, Some(0x100)).unwrap();
-        assert_eq!(pool.allocate(0x110), Some(0x1000));
-        assert_eq!(pool.allocate(0x100), Some(0x1200));
+        assert_eq!(
+            pool.allocate(0x110, Alloc::Anon(0), String::from("bar0")),
+            Ok(0x1000)
+        );
+        assert_eq!(
+            pool.allocate(0x100, Alloc::Anon(1), String::from("bar1")),
+            Ok(0x1200)
+        );
+    }
+
+    #[test]
+    fn allocate_retrieve_alloc() {
+        let mut pool = AddressAllocator::new(0x1000, 0x10000, Some(0x100)).unwrap();
+        assert_eq!(
+            pool.allocate(0x110, Alloc::Anon(0), String::from("bar0")),
+            Ok(0x1000)
+        );
+        assert_eq!(
+            pool.get(&Alloc::Anon(0)),
+            Some(&(0x1000, 0x110, String::from("bar0")))
+        );
     }
 }