[pvmfw] Move MemorySharer from pvmfw to vmbase
This cl mvoes MemorySharer and two utility functions
virt_to_phys and phys_to_virt from pvmfw to vmbase for reuse in
rialto later.
Bug: 284462758
Test: m pvmfw_img
Change-Id: I48a410792370beaa531ea0408670b8d831150272
diff --git a/vmbase/src/memory/shared.rs b/vmbase/src/memory/shared.rs
new file mode 100644
index 0000000..0a2444f
--- /dev/null
+++ b/vmbase/src/memory/shared.rs
@@ -0,0 +1,78 @@
+// Copyright 2023, The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Shared memory management.
+
+use super::util::virt_to_phys;
+use alloc::alloc::{alloc_zeroed, dealloc, handle_alloc_error};
+use alloc::vec::Vec;
+use buddy_system_allocator::FrameAllocator;
+use core::alloc::Layout;
+use core::ptr::NonNull;
+use hyp::get_hypervisor;
+use log::trace;
+
+/// Allocates memory on the heap and shares it with the host.
+///
+/// Unshares all pages when dropped.
+pub struct MemorySharer {
+ granule: usize,
+ shared_regions: Vec<(usize, Layout)>,
+}
+
+impl MemorySharer {
+ /// Constructs a new `MemorySharer` instance with the specified granule size and capacity.
+ /// `granule` must be a power of 2.
+ pub fn new(granule: usize, capacity: usize) -> Self {
+ assert!(granule.is_power_of_two());
+ Self { granule, shared_regions: Vec::with_capacity(capacity) }
+ }
+
+ /// Get from the global allocator a granule-aligned region that suits `hint` and share it.
+ pub fn refill(&mut self, pool: &mut FrameAllocator<32>, hint: Layout) {
+ let layout = hint.align_to(self.granule).unwrap().pad_to_align();
+ assert_ne!(layout.size(), 0);
+ // SAFETY - layout has non-zero size.
+ let Some(shared) = NonNull::new(unsafe { alloc_zeroed(layout) }) else {
+ handle_alloc_error(layout);
+ };
+
+ let base = shared.as_ptr() as usize;
+ let end = base.checked_add(layout.size()).unwrap();
+ trace!("Sharing memory region {:#x?}", base..end);
+ for vaddr in (base..end).step_by(self.granule) {
+ let vaddr = NonNull::new(vaddr as *mut _).unwrap();
+ get_hypervisor().mem_share(virt_to_phys(vaddr).try_into().unwrap()).unwrap();
+ }
+ self.shared_regions.push((base, layout));
+
+ pool.add_frame(base, end);
+ }
+}
+
+impl Drop for MemorySharer {
+ fn drop(&mut self) {
+ while let Some((base, layout)) = self.shared_regions.pop() {
+ let end = base.checked_add(layout.size()).unwrap();
+ trace!("Unsharing memory region {:#x?}", base..end);
+ for vaddr in (base..end).step_by(self.granule) {
+ let vaddr = NonNull::new(vaddr as *mut _).unwrap();
+ get_hypervisor().mem_unshare(virt_to_phys(vaddr).try_into().unwrap()).unwrap();
+ }
+
+ // SAFETY - The region was obtained from alloc_zeroed() with the recorded layout.
+ unsafe { dealloc(base as *mut _, layout) };
+ }
+ }
+}