vmm: Introduce option --platform iommufd=on|off

This option allows user to configure VFIO device pass-through with
iommufd (e.g. vfio cdev mode) or not (e.g. vfio legacy mode).

Signed-off-by: Bo Chen <bchen@crusoe.ai>

vmm/src/api/openapi/cloud-hypervisor.yaml

@@ -794,6 +794,9 @@ components:
         sev_snp:
           type: boolean
           default: false
+        iommufd:
+          type: boolean
+          default: false
 
     MemoryZoneConfig:
       required:

vmm/src/config.rs

@@ -804,7 +804,7 @@ impl PlatformConfig {
             let mut syntax = "Platform configuration parameters \
             \"num_pci_segments=<num_pci_segments>,iommu_segments=<list_of_segments>,\
             iommu_address_width=<bits>,serial_number=<dmi_device_serial_number>,\
-            uuid=<dmi_device_uuid>,oem_strings=<list_of_strings>"
+            uuid=<dmi_device_uuid>,oem_strings=<list_of_strings>,iommufd=on|off"
                 .to_string();
 
             if cfg!(feature = "tdx") {
@@ -831,7 +831,8 @@ impl PlatformConfig {
             .add("iommu_address_width")
             .add("serial_number")
             .add("uuid")
-            .add("oem_strings");
+            .add("oem_strings")
+            .add("iommufd");
         #[cfg(feature = "tdx")]
         parser.add("tdx");
         #[cfg(feature = "sev_snp")]
@@ -858,6 +859,11 @@ impl PlatformConfig {
             .convert::<StringList>("oem_strings")
             .map_err(Error::ParsePlatform)?
             .map(|v| v.0);
+        let iommufd = parser
+            .convert::<Toggle>("iommufd")
+            .map_err(Error::ParsePlatform)?
+            .unwrap_or(Toggle(false))
+            .0;
         #[cfg(feature = "tdx")]
         let tdx = parser
             .convert::<Toggle>("tdx")
@@ -877,6 +883,7 @@ impl PlatformConfig {
             serial_number,
             uuid,
             oem_strings,
+            iommufd,
             #[cfg(feature = "tdx")]
             tdx,
             #[cfg(feature = "sev_snp")]
@@ -4824,6 +4831,7 @@ id=\"{id}\",pci_segment={pci_segment},queue_sizes={queue_sizes}"
             serial_number: None,
             uuid: None,
             oem_strings: None,
+            iommufd: false,
             #[cfg(feature = "tdx")]
             tdx: false,
             #[cfg(feature = "sev_snp")]

vmm/src/vm_config.rs

@@ -133,6 +133,8 @@ pub struct PlatformConfig {
     #[cfg(feature = "sev_snp")]
     #[serde(default)]
     pub sev_snp: bool,
+    #[serde(default)]
+    pub iommufd: bool,
 }
 
 pub const DEFAULT_PCI_SEGMENT_APERTURE_WEIGHT: u32 = 1;