Map PCI CAM MMIO region and register pages with the MMIO guard.
Crosvm uses a memory-mapped Configuration Access Mechanism for PCI,
which we can find in the device tree. We need to map this as device
memory and register it with the hypervisor MMIO guard before trying to
access any PCI devices.
Bug: 237249346
Test: Ran pVM firmware manually.
Change-Id: Ide892c307e0c77a968560ecc6cb64f336002edf2
diff --git a/pvmfw/src/pci.rs b/pvmfw/src/pci.rs
new file mode 100644
index 0000000..7baabed
--- /dev/null
+++ b/pvmfw/src/pci.rs
@@ -0,0 +1,74 @@
+// Copyright 2022, 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.
+
+//! Functions to scan the PCI bus for VirtIO device and allocate BARs.
+
+use crate::{entry::RebootReason, memory::MemoryTracker};
+use core::ffi::CStr;
+use libfdt::{Fdt, FdtNode};
+use log::{debug, error};
+
+/// PCI MMIO configuration region size.
+const PCI_CFG_SIZE: usize = 0x100_0000;
+
+/// Finds an FDT node with compatible=pci-host-cam-generic.
+pub fn pci_node(fdt: &Fdt) -> Result<FdtNode, RebootReason> {
+ fdt.compatible_nodes(CStr::from_bytes_with_nul(b"pci-host-cam-generic\0").unwrap())
+ .map_err(|e| {
+ error!("Failed to find PCI bus in FDT: {}", e);
+ RebootReason::InvalidFdt
+ })?
+ .next()
+ .ok_or(RebootReason::InvalidFdt)
+}
+
+pub fn map_cam(pci_node: &FdtNode, memory: &mut MemoryTracker) -> Result<(), RebootReason> {
+ // Parse reg property to find CAM.
+ let pci_reg = pci_node
+ .reg()
+ .map_err(|e| {
+ error!("Error getting reg property from PCI node: {}", e);
+ RebootReason::InvalidFdt
+ })?
+ .ok_or_else(|| {
+ error!("PCI node missing reg property.");
+ RebootReason::InvalidFdt
+ })?
+ .next()
+ .ok_or_else(|| {
+ error!("Empty reg property on PCI node.");
+ RebootReason::InvalidFdt
+ })?;
+ let cam_addr = pci_reg.addr as usize;
+ let cam_size = pci_reg.size.ok_or_else(|| {
+ error!("PCI reg property missing size.");
+ RebootReason::InvalidFdt
+ })? as usize;
+ debug!("Found PCI CAM at {:#x}-{:#x}", cam_addr, cam_addr + cam_size);
+ // Check that the CAM is the size we expect, so we don't later try accessing it beyond its
+ // bounds. If it is a different size then something is very wrong and we shouldn't continue to
+ // access it; maybe there is some new version of PCI we don't know about.
+ if cam_size != PCI_CFG_SIZE {
+ error!("FDT says PCI CAM is {} bytes but we expected {}.", cam_size, PCI_CFG_SIZE);
+ return Err(RebootReason::InvalidFdt);
+ }
+
+ // Map the CAM as MMIO.
+ memory.map_mmio_range(cam_addr..cam_addr + cam_size).map_err(|e| {
+ error!("Failed to map PCI CAM: {}", e);
+ RebootReason::InternalError
+ })?;
+
+ Ok(())
+}