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vmm: device_manager: handle short ACPI hotplug MMIO width gracefully

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The BusDevice read and write arms for B0EJ_FIELD_OFFSET and
PSEG_FIELD_OFFSET opened with assert!/assert_eq! on data.len(), so a
guest 1/2/8-byte MMIO access to either register panicked the vCPU
thread.  Replace each assert with a warn! and early return so unusual
access widths are logged and ignored instead of crashing the VMM.

Signed-off-by: Dylan Reid <dgreid@fb.com>
This commit is contained in:
Dylan Reid
2026-05-04 23:34:31 -07:00
committed by Rob Bradford
parent e1c2b179e7
commit 6111d549b7
1 changed files with 16 additions and 4 deletions
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20
vmm/src/device_manager.rs
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@@ -5645,13 +5645,19 @@ impl BusDevice for DeviceManager {
self.pci_segments[self.selected_segment].pci_devices_down = 0;
}
B0EJ_FIELD_OFFSET => {
assert!(data.len() == B0EJ_FIELD_SIZE);
if data.len() != B0EJ_FIELD_SIZE {
warn!("Unexpected B0EJ read width: {}", data.len());
return;
}
// Always return an empty bitmap since the eject is always
// taken care of right away during a write access.
data.fill(0);
}
PSEG_FIELD_OFFSET => {
assert_eq!(data.len(), PSEG_FIELD_SIZE);
if data.len() != PSEG_FIELD_SIZE {
warn!("Unexpected PSEG read width: {}", data.len());
return;
}
data.copy_from_slice(&(self.selected_segment as u32).to_le_bytes());
}
_ => error!("Accessing unknown location at base 0x{base:x}, offset 0x{offset:x}"),
@@ -5663,7 +5669,10 @@ impl BusDevice for DeviceManager {
fn write(&mut self, base: u64, offset: u64, data: &[u8]) -> Option<Arc<std::sync::Barrier>> {
match offset {
B0EJ_FIELD_OFFSET => {
assert!(data.len() == B0EJ_FIELD_SIZE);
if data.len() != B0EJ_FIELD_SIZE {
warn!("Unexpected B0EJ write width: {}", data.len());
return None;
}
let mut data_array: [u8; 4] = [0, 0, 0, 0];
data_array.copy_from_slice(data);
let mut slot_bitmap = u32::from_le_bytes(data_array);
@@ -5678,7 +5687,10 @@ impl BusDevice for DeviceManager {
}
}
PSEG_FIELD_OFFSET => {
assert_eq!(data.len(), PSEG_FIELD_SIZE);
if data.len() != PSEG_FIELD_SIZE {
warn!("Unexpected PSEG write width: {}", data.len());
return None;
}
let mut data_array: [u8; 4] = [0, 0, 0, 0];
data_array.copy_from_slice(data);
let selected_segment = u32::from_le_bytes(data_array) as usize;