vmm: add pci_segment mmio aperture configs

When using multiple PCI segments, the 32-bit and 64-bit mmio
aperture is split equally between each segment. Add an option
to configure the 'weight'. For example, a PCI segment with a
`mmio32_aperture_weight` of 2 will be allocated twice as much
32-bit mmio space as a normal PCI segment.

Signed-off-by: Thomas Barrett <tbarrett@crusoeenergy.com>

src/main.rs

@@ -355,6 +355,13 @@ fn create_app(default_vcpus: String, default_memory: String, default_rng: String
                 .num_args(1..)
                 .group("vm-config"),
         )
+        .arg(
+            Arg::new("pci-segment")
+                .long("pci-segment")
+                .help(config::PciSegmentConfig::SYNTAX)
+                .num_args(1..)
+                .group("vm-config"),
+        )
         .arg(
             Arg::new("watchdog")
                 .long("watchdog")
@@ -934,6 +941,7 @@ mod unit_tests {
             watchdog: false,
             #[cfg(feature = "guest_debug")]
             gdb: false,
+            pci_segments: None,
             platform: None,
             tpm: None,
             preserved_fds: None,