virtio-pci: allow configuration of pci from config json

 - pci can be enabled/disabled for all mmio devices
 - if pci is enabled, multiple vfio devices can be added

only one vfio device works. multiple tigger errno 16: device or resource
busy

Signed-off-by: Riccardo Mancini <[email protected]>

Author: Manciukic

src/vmm/src/acpi/mod.rs

@@ -79,7 +79,7 @@ impl<'a> AcpiTableWriter<'a> {
     fn build_dsdt(
         &mut self,
         mmio_device_manager: &MMIODeviceManager,
-        pci_segment: &PciSegment,
+        pci_segment: Option<&PciSegment>,
         acpi_device_manager: &ACPIDeviceManager,
     ) -> Result<u64, AcpiError> {
         let mut dsdt_data = Vec::new();
@@ -93,7 +93,9 @@ impl<'a> AcpiTableWriter<'a> {
         // Architecture specific DSDT data
         setup_arch_dsdt(&mut dsdt_data);
 
-        pci_segment.append_aml_bytes(&mut dsdt_data);
+        if let Some(pci_segment) = pci_segment {
+            pci_segment.append_aml_bytes(&mut dsdt_data);
+        }
 
         let mut dsdt = Dsdt::new(OEM_ID, *b"FCVMDSDT", OEM_REVISION, dsdt_data);
         self.write_acpi_table(&mut dsdt)
@@ -130,12 +132,17 @@ impl<'a> AcpiTableWriter<'a> {
     /// Build the XSDT table for the guest
     ///
     /// Currently, we pass to the guest just FADT and MADT tables.
-    fn build_xsdt(&mut self, fadt_addr: u64, madt_addr: u64, mcfg_addr: u64) -> Result<u64, AcpiError> {
+    fn build_xsdt(&mut self, fadt_addr: u64, madt_addr: u64, mcfg_addr: Option<u64>) -> Result<u64, AcpiError> {
+        let tables = if let Some(mcfg_addr) = mcfg_addr {
+            vec![fadt_addr, madt_addr, mcfg_addr]
+        } else {
+            vec![fadt_addr, madt_addr]
+        };
         let mut xsdt = Xsdt::new(
             OEM_ID,
             *b"FCMVXSDT",
             OEM_REVISION,
-            vec![fadt_addr, madt_addr, mcfg_addr],
+            tables,
         );
         self.write_acpi_table(&mut xsdt)
     }
@@ -181,7 +188,7 @@ pub(crate) fn create_acpi_tables(
     resource_allocator: &mut ResourceAllocator,
     mmio_device_manager: &MMIODeviceManager,
     acpi_device_manager: &ACPIDeviceManager,
-    pci_segment: &PciSegment,
+    pci_segment: Option<&PciSegment>,
     pci_mmio_config_addr: u64,
     vcpus: &[Vcpu],
 ) -> Result<(), AcpiError> {
@@ -193,7 +200,7 @@ pub(crate) fn create_acpi_tables(
     let dsdt_addr = writer.build_dsdt(mmio_device_manager, pci_segment, acpi_device_manager)?;
     let fadt_addr = writer.build_fadt(dsdt_addr)?;
     let madt_addr = writer.build_madt(vcpus.len().try_into().unwrap())?;
-    let mcfg_addr = writer.build_mcfg(pci_mmio_config_addr)?;
+    let mcfg_addr = pci_segment.map(|_| writer.build_mcfg(pci_mmio_config_addr)).transpose()?;
     let xsdt_addr = writer.build_xsdt(fadt_addr, madt_addr, mcfg_addr)?;
     writer.build_rsdp(xsdt_addr)
 }