vmm: add NVIDIA GPUDirect P2P support

On platforms where PCIe P2P is supported, inject a PCI capability into
NVIDIA GPU to indicate support.

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

pci/src/vfio.rs

@@ -419,6 +419,7 @@ pub(crate) struct VfioCommon {
     pub(crate) legacy_interrupt_group: Option<Arc<dyn InterruptSourceGroup>>,
     pub(crate) vfio_wrapper: Arc<dyn Vfio>,
     pub(crate) patches: HashMap<usize, ConfigPatch>,
+    x_nv_gpudirect_clique: Option<u8>,
 }
 
 impl VfioCommon {
@@ -429,6 +430,7 @@ impl VfioCommon {
         subclass: &dyn PciSubclass,
         bdf: PciBdf,
         snapshot: Option<Snapshot>,
+        x_nv_gpudirect_clique: Option<u8>,
     ) -> Result<Self, VfioPciError> {
         let pci_configuration_state =
             vm_migration::versioned_state_from_id(snapshot.as_ref(), PCI_CONFIGURATION_ID)
@@ -465,6 +467,7 @@ impl VfioCommon {
             legacy_interrupt_group,
             vfio_wrapper,
             patches: HashMap::new(),
+            x_nv_gpudirect_clique,
         };
 
         let state: Option<VfioCommonState> = snapshot
@@ -859,15 +862,15 @@ impl VfioCommon {
     }
 
     pub(crate) fn parse_capabilities(&mut self, bdf: PciBdf) {
-        let mut cap_next = self
+        let mut cap_iter = self
             .vfio_wrapper
             .read_config_byte(PCI_CONFIG_CAPABILITY_OFFSET);
 
         let mut pci_express_cap_found = false;
         let mut power_management_cap_found = false;
 
-        while cap_next != 0 {
-            let cap_id = self.vfio_wrapper.read_config_byte(cap_next.into());
+        while cap_iter != 0 {
+            let cap_id = self.vfio_wrapper.read_config_byte(cap_iter.into());
 
             match PciCapabilityId::from(cap_id) {
                 PciCapabilityId::MessageSignalledInterrupts => {
@@ -875,8 +878,8 @@ impl VfioCommon {
                         if irq_info.count > 0 {
                             // Parse capability only if the VFIO device
                             // supports MSI.
-                            let msg_ctl = self.parse_msi_capabilities(cap_next);
-                            self.initialize_msi(msg_ctl, cap_next as u32, None);
+                            let msg_ctl = self.parse_msi_capabilities(cap_iter);
+                            self.initialize_msi(msg_ctl, cap_iter as u32, None);
                         }
                     }
                 }
@@ -886,8 +889,8 @@ impl VfioCommon {
                         if irq_info.count > 0 {
                             // Parse capability only if the VFIO device
                             // supports MSI-X.
-                            let msix_cap = self.parse_msix_capabilities(cap_next);
-                            self.initialize_msix(msix_cap, cap_next as u32, bdf, None);
+                            let msix_cap = self.parse_msix_capabilities(cap_iter);
+                            self.initialize_msix(msix_cap, cap_iter as u32, bdf, None);
                         }
                     }
                 }
@@ -896,7 +899,16 @@ impl VfioCommon {
                 _ => {}
             };
 
-            cap_next = self.vfio_wrapper.read_config_byte((cap_next + 1).into());
+            let cap_next = self.vfio_wrapper.read_config_byte((cap_iter + 1).into());
+            if cap_next == 0 {
+                break;
+            }
+
+            cap_iter = cap_next;
+        }
+
+        if let Some(clique_id) = self.x_nv_gpudirect_clique {
+            self.add_nv_gpudirect_clique_cap(cap_iter, clique_id);
         }
 
         if pci_express_cap_found && power_management_cap_found {
@@ -904,6 +916,37 @@ impl VfioCommon {
         }
     }
 
+    fn add_nv_gpudirect_clique_cap(&mut self, cap_iter: u8, clique_id: u8) {
+        // Turing, Ampere, Hopper, and Lovelace GPUs have dedicated space
+        // at 0xD4 for this capability.
+        let cap_offset = 0xd4u32;
+
+        let reg_idx = (cap_iter / 4) as usize;
+        self.patches.insert(
+            reg_idx,
+            ConfigPatch {
+                mask: 0x0000_ff00,
+                patch: cap_offset << 8,
+            },
+        );
+
+        let reg_idx = (cap_offset / 4) as usize;
+        self.patches.insert(
+            reg_idx,
+            ConfigPatch {
+                mask: 0xffff_ffff,
+                patch: 0x50080009u32,
+            },
+        );
+        self.patches.insert(
+            reg_idx + 1,
+            ConfigPatch {
+                mask: 0xffff_ffff,
+                patch: u32::from(clique_id) << 19 | 0x5032,
+            },
+        );
+    }
+
     fn parse_extended_capabilities(&mut self) {
         let mut current_offset = PCI_CONFIG_EXTENDED_CAPABILITY_OFFSET;
 
@@ -1351,6 +1394,7 @@ impl VfioPciDevice {
         bdf: PciBdf,
         memory_slot: Arc<dyn Fn() -> u32 + Send + Sync>,
         snapshot: Option<Snapshot>,
+        x_nv_gpudirect_clique: Option<u8>,
     ) -> Result<Self, VfioPciError> {
         let device = Arc::new(device);
         device.reset();
@@ -1364,6 +1408,7 @@ impl VfioPciDevice {
             &PciVfioSubclass::VfioSubclass,
             bdf,
             vm_migration::snapshot_from_id(snapshot.as_ref(), VFIO_COMMON_ID),
+            x_nv_gpudirect_clique,
         )?;
 
         let vfio_pci_device = VfioPciDevice {

pci/src/vfio_user.rs

@@ -94,6 +94,7 @@ impl VfioUserPciDevice {
             &PciVfioUserSubclass::VfioUserSubclass,
             bdf,
             vm_migration::snapshot_from_id(snapshot.as_ref(), VFIO_COMMON_ID),
+            None,
         )
         .map_err(VfioUserPciDeviceError::CreateVfioCommon)?;
 

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

@@ -1046,7 +1046,9 @@ components:
           format: int16
         id:
           type: string
-
+        x_nv_gpudirect_clique:
+          type: integer
+          format: int8
     TpmConfig:
       required:
         - socket

vmm/src/config.rs

@@ -1746,7 +1746,12 @@ impl DeviceConfig {
 
     pub fn parse(device: &str) -> Result<Self> {
         let mut parser = OptionParser::new();
-        parser.add("path").add("id").add("iommu").add("pci_segment");
+        parser
+            .add("path")
+            .add("id")
+            .add("iommu")
+            .add("pci_segment")
+            .add("x_nv_gpudirect_clique");
         parser.parse(device).map_err(Error::ParseDevice)?;
 
         let path = parser
@@ -1763,12 +1768,15 @@ impl DeviceConfig {
             .convert::<u16>("pci_segment")
             .map_err(Error::ParseDevice)?
             .unwrap_or_default();
-
+        let x_nv_gpudirect_clique = parser
+            .convert::<u8>("x_nv_gpudirect_clique")
+            .map_err(Error::ParseDevice)?;
         Ok(DeviceConfig {
             path,
             iommu,
             id,
             pci_segment,
+            x_nv_gpudirect_clique,
         })
     }
 
@@ -3324,6 +3332,7 @@ mod tests {
             id: None,
             iommu: false,
             pci_segment: 0,
+            x_nv_gpudirect_clique: None,
         }
     }
 

vmm/src/device_manager.rs

@@ -3510,6 +3510,7 @@ impl DeviceManager {
             pci_device_bdf,
             Arc::new(move || memory_manager.lock().unwrap().allocate_memory_slot()),
             vm_migration::snapshot_from_id(self.snapshot.as_ref(), vfio_name.as_str()),
+            device_cfg.x_nv_gpudirect_clique,
         )
         .map_err(DeviceManagerError::VfioPciCreate)?;
 

vmm/src/vm_config.rs

@@ -434,6 +434,8 @@ pub struct DeviceConfig {
     pub id: Option<String>,
     #[serde(default)]
     pub pci_segment: u16,
+    #[serde(default)]
+    pub x_nv_gpudirect_clique: Option<u8>,
 }
 
 #[derive(Clone, Debug, PartialEq, Eq, Deserialize, Serialize)]