Manage PCI MSI/PCI MSI-x interrupts

Implement interrupt source driver to manage PCI MSI/MSI-x interrupts.

Signed-off-by: Liu Jiang <[email protected]>
Signed-off-by: Bin Zha <[email protected]>

Cargo.toml

@@ -18,3 +18,4 @@ vm-memory = { git = "https://github.com/rust-vmm/vm-memory" }
 kvm_irq = ["kvm-ioctls", "kvm-bindings"]
 legacy_irq = []
 msi_irq = []
+pci_msi_irq = ["msi_irq"]

src/interrupt/kvm/mod.rs

@@ -36,6 +36,11 @@ use self::legacy_irq::LegacyIrq;
 #[cfg(feature = "msi_irq")]
 mod msi_irq;
 
+#[cfg(feature = "pci_msi_irq")]
+mod pci_msi_irq;
+#[cfg(feature = "pci_msi_irq")]
+use self::pci_msi_irq::PciMsiIrq;
+
 /// Structure to manage interrupt sources for a virtual machine based on the Linux KVM framework.
 ///
 /// The KVM framework provides methods to inject interrupts into the target virtual machines,
@@ -119,7 +124,7 @@ impl KvmIrqManagerObj {
                 LegacyIrq::new(base, count, self.vmfd.clone(), self.routes.clone())?
             }
             #[cfg(feature = "pci_msi_irq")]
-            InterruptSourceType::MsiIrq => {
+            InterruptSourceType::PciMsiIrq => {
                 PciMsiIrq::new(base, count, self.vmfd.clone(), self.routes.clone())?
             }
         };

src/interrupt/kvm/pci_msi_irq.rs

@@ -0,0 +1,147 @@
+// Copyright (C) 2019 Alibaba Cloud. All rights reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+//! Manage virtual device's PCI MSI/PCI MSIx interrupts based on Linux KVM framework.
+//!
+//! To optimize for performance by avoiding unnecessary locking and state checking, we assume that
+//! the caller will take the responsibility to maintain the interrupt states and only issue valid
+//! requests to this driver. If the caller doesn't obey the contract, only the current virtual
+//! machine will be affected, it shouldn't break the host or other virtual machines.
+
+use super::msi_irq::{create_msi_routing_entries, new_msi_routing_entry, MsiConfig};
+use super::*;
+
+pub(super) struct PciMsiIrq {
+    base: InterruptIndex,
+    count: InterruptIndex,
+    vmfd: Arc<VmFd>,
+    irq_routing: Arc<KvmIrqRouting>,
+    msi_configs: Vec<MsiConfig>,
+}
+
+impl PciMsiIrq {
+    #[allow(clippy::new_ret_no_self)]
+    pub(super) fn new(
+        base: InterruptIndex,
+        count: InterruptIndex,
+        vmfd: Arc<VmFd>,
+        irq_routing: Arc<KvmIrqRouting>,
+    ) -> Result<Arc<Box<dyn InterruptSourceGroup>>> {
+        if count > MAX_MSI_IRQS_PER_DEVICE || base >= MAX_IRQS || base + count > MAX_IRQS {
+            return Err(std::io::Error::from_raw_os_error(libc::EINVAL));
+        }
+
+        let mut msi_configs = Vec::with_capacity(count as usize);
+        for _ in 0..count {
+            msi_configs.push(MsiConfig::new());
+        }
+
+        Ok(Arc::new(Box::new(PciMsiIrq {
+            base,
+            count,
+            vmfd,
+            irq_routing,
+            msi_configs,
+        })))
+    }
+}
+
+impl InterruptSourceGroup for PciMsiIrq {
+    fn interrupt_type(&self) -> InterruptSourceType {
+        InterruptSourceType::PciMsiIrq
+    }
+
+    fn len(&self) -> u32 {
+        self.count
+    }
+
+    fn base(&self) -> u32 {
+        self.base
+    }
+
+    fn irqfd(&self, index: InterruptIndex) -> Option<&EventFd> {
+        if index >= self.count {
+            None
+        } else {
+            let msi_config = &self.msi_configs[index as usize];
+            Some(&msi_config.irqfd)
+        }
+    }
+
+    fn enable(&self, configs: &[InterruptSourceConfig]) -> Result<()> {
+        if configs.len() != self.count as usize {
+            return Err(std::io::Error::from_raw_os_error(libc::EINVAL));
+        }
+
+        // First add IRQ routings for all the MSI interrupts.
+        let entries = create_msi_routing_entries(self.base, configs)?;
+        self.irq_routing.add(&entries)?;
+
+        // Then register irqfds to the KVM module.
+        for i in 0..self.count {
+            let irqfd = &self.msi_configs[i as usize].irqfd;
+            self.vmfd.register_irqfd(irqfd, self.base + i)?;
+        }
+
+        Ok(())
+    }
+
+    fn disable(&self) -> Result<()> {
+        // First unregister all irqfds, so it won't trigger anymore.
+        for i in 0..self.count {
+            let irqfd = &self.msi_configs[i as usize].irqfd;
+            self.vmfd.unregister_irqfd(irqfd, self.base + i)?;
+        }
+
+        // Then tear down the IRQ routings for all the MSI interrupts.
+        let mut entries = Vec::with_capacity(self.count as usize);
+        for i in 0..self.count {
+            // Safe to unwrap because there's no legal way to break the mutex.
+            let msicfg = self.msi_configs[i as usize].config.lock().unwrap();
+            let entry = new_msi_routing_entry(self.base + i, &*msicfg);
+            entries.push(entry);
+        }
+        self.irq_routing.remove(&entries)?;
+
+        Ok(())
+    }
+
+    #[allow(irrefutable_let_patterns)]
+    fn update(&self, index: InterruptIndex, config: &InterruptSourceConfig) -> Result<()> {
+        if index >= self.count {
+            return Err(std::io::Error::from_raw_os_error(libc::EINVAL));
+        }
+
+        if let InterruptSourceConfig::MsiIrq(ref cfg) = config {
+            // Safe to unwrap because there's no legal way to break the mutex.
+            let entry = {
+                let mut msicfg = self.msi_configs[index as usize].config.lock().unwrap();
+                msicfg.high_addr = cfg.high_addr;
+                msicfg.low_addr = cfg.low_addr;
+                msicfg.data = cfg.data;
+                new_msi_routing_entry(self.base + index, &*msicfg)
+            };
+            self.irq_routing.modify(&entry)
+        } else {
+            Err(std::io::Error::from_raw_os_error(libc::EINVAL))
+        }
+    }
+
+    fn trigger(&self, index: InterruptIndex, flags: u32) -> Result<()> {
+        // Assume that the caller will maintain the interrupt states and only call this function
+        // when suitable.
+        if index >= self.count || flags != 0 {
+            return Err(std::io::Error::from_raw_os_error(libc::EINVAL));
+        }
+        let msi_config = &self.msi_configs[index as usize];
+        msi_config.irqfd.write(1)
+    }
+
+    fn ack(&self, index: InterruptIndex, flags: u32) -> Result<()> {
+        // It's a noop to acknowledge an edge triggered MSI interrupts.
+        if index >= self.count || flags != 0 {
+            return Err(std::io::Error::from_raw_os_error(libc::EINVAL));
+        }
+        Ok(())
+    }
+}