agent: implement NVDIMM/PMEM block driver

Support pmem-csi[1] k8s pluging, unlike SCSI and virtio devices,
NVDIMM/PMEM devices support DAX, improving IO Read and Write
operations.

fixes #1289

Signed-off-by: Julio Montes <julio.montes@intel.com>

[1]: https://github.com/intel/pmem-csi

src/agent/src/device.rs

@@ -162,6 +162,14 @@ pub async fn get_pci_device_name(sandbox: &Arc<Mutex<Sandbox>>, pci_id: &str) ->
     get_device_name(sandbox, &pci_addr).await
 }
 
+pub async fn get_pmem_device_name(
+    sandbox: &Arc<Mutex<Sandbox>>,
+    pmem_devname: &str,
+) -> Result<String> {
+    let dev_sub_path = format!("/{}/{}", SCSI_BLOCK_SUFFIX, pmem_devname);
+    get_device_name(sandbox, &dev_sub_path).await
+}
+
 /// Scan SCSI bus for the given SCSI address(SCSI-Id and LUN)
 fn scan_scsi_bus(scsi_addr: &str) -> Result<()> {
     let tokens: Vec<&str> = scsi_addr.split(':').collect();

src/agent/src/linux_abi.rs

@@ -58,6 +58,13 @@ pub fn create_pci_root_bus_path() -> String {
     ret
 }
 
+// From https://www.kernel.org/doc/Documentation/acpi/namespace.txt
+// The Linux kernel's core ACPI subsystem creates struct acpi_device
+// objects for ACPI namespace objects representing devices, power resources
+// processors, thermal zones. Those objects are exported to user space via
+// sysfs as directories in the subtree under /sys/devices/LNXSYSTM:00
+pub const ACPI_DEV_PATH: &str = "/devices/LNXSYSTM";
+
 pub const SYSFS_CPU_ONLINE_PATH: &str = "/sys/devices/system/cpu";
 
 pub const SYSFS_MEMORY_BLOCK_SIZE_PATH: &str = "/sys/devices/system/memory/block_size_bytes";

src/agent/src/mount.rs

@@ -22,7 +22,9 @@ use regex::Regex;
 use std::fs::File;
 use std::io::{BufRead, BufReader};
 
-use crate::device::{get_pci_device_name, get_scsi_device_name, online_device};
+use crate::device::{
+    get_pci_device_name, get_pmem_device_name, get_scsi_device_name, online_device,
+};
 use crate::linux_abi::*;
 use crate::protocols::agent::Storage;
 use crate::Sandbox;
@@ -122,7 +124,7 @@ lazy_static! {
     ];
 }
 
-pub const STORAGE_HANDLER_LIST: [&str; 7] = [
+pub const STORAGE_HANDLER_LIST: [&str; 8] = [
     DRIVERBLKTYPE,
     DRIVER9PTYPE,
     DRIVERVIRTIOFSTYPE,
@@ -130,6 +132,7 @@ pub const STORAGE_HANDLER_LIST: [&str; 7] = [
     DRIVERMMIOBLKTYPE,
     DRIVERLOCALTYPE,
     DRIVERSCSITYPE,
+    DRIVERNVDIMMTYPE,
 ];
 
 #[derive(Debug, Clone)]
@@ -347,6 +350,32 @@ fn common_storage_handler(logger: &Logger, storage: &Storage) -> Result<String>
     mount_storage(logger, storage).and(Ok(mount_point))
 }
 
+// nvdimm_storage_handler handles the storage for NVDIMM driver.
+async fn nvdimm_storage_handler(
+    logger: &Logger,
+    storage: &Storage,
+    sandbox: Arc<Mutex<Sandbox>>,
+) -> Result<String> {
+    let mut storage = storage.clone();
+    // If hot-plugged, get the device node path based on the PCI address else
+    // use the virt path provided in Storage Source
+    let pmem_devname = match storage.source.strip_prefix("/dev/") {
+        Some(dev) => dev,
+        None => {
+            return Err(anyhow!(
+                "Storage source '{}' must start with /dev/",
+                storage.source
+            ))
+        }
+    };
+
+    // Retrieve the device path from NVDIMM address.
+    let dev_path = get_pmem_device_name(&sandbox, pmem_devname).await?;
+    storage.source = dev_path;
+
+    common_storage_handler(logger, &storage)
+}
+
 // mount_storage performs the mount described by the storage structure.
 fn mount_storage(logger: &Logger, storage: &Storage) -> Result<()> {
     let logger = logger.new(o!("subsystem" => "mount"));
@@ -441,6 +470,7 @@ pub async fn add_storages(
             }
             DRIVERLOCALTYPE => local_storage_handler(&logger, &storage, sandbox.clone()).await,
             DRIVERSCSITYPE => virtio_scsi_storage_handler(&logger, &storage, sandbox.clone()).await,
+            DRIVERNVDIMMTYPE => nvdimm_storage_handler(&logger, &storage, sandbox.clone()).await,
             _ => {
                 return Err(anyhow!(
                     "Failed to find the storage handler {}",

src/agent/src/uevent.rs

@@ -54,7 +54,10 @@ impl Uevent {
         let pci_root_bus_path = create_pci_root_bus_path();
         self.action == U_EVENT_ACTION_ADD
             && self.subsystem == "block"
-            && self.devpath.starts_with(&pci_root_bus_path)
+            && {
+                self.devpath.starts_with(pci_root_bus_path.as_str())
+                    || self.devpath.starts_with(ACPI_DEV_PATH) // NVDIMM/PMEM devices
+            }
             && self.devname != ""
     }
 
@@ -84,6 +87,13 @@ impl Uevent {
                 {
                     (*dev_addr).ends_with(SCSI_BLOCK_SUFFIX) &&
                         devpath.contains(*dev_addr)
+                } ||
+                // nvdimm/pmem device
+                {
+                    let pmem_suffix = format!("/{}/{}", SCSI_BLOCK_SUFFIX, self.devname);
+                    devpath.starts_with(ACPI_DEV_PATH) &&
+                        devpath.ends_with(pmem_suffix.as_str()) &&
+                        dev_addr.ends_with(pmem_suffix.as_str())
                 }
             })
             .map(|(k, sender)| {