crosvm: Add plumbing for split-irqchip interrupts

Devices use irqfd to inject interrupts, we listen to them in the main
thread and activate userspace pic/ioapic accordingly.

BUG=chromium:908689
TEST=lanuch linux guest with `--split-irqchip` flag

Change-Id: If30d17ce7ec9e26dba782c89cc1b9b2ff897a70d
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/1945798
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Stephen Barber <smbarber@chromium.org>
Reviewed-by: Daniel Verkamp <dverkamp@chromium.org>
Commit-Queue: Zhuocheng Ding <zhuocheng.ding@intel.corp-partner.google.com>

1 files changed, 34 insertions, 0 deletions

diff --git a/devices/src/split_irqchip_common.rs b/devices/src/split_irqchip_common.rs
index b54c35a..1e513f2 100644
--- a/devices/src/split_irqchip_common.rs
+++ b/devices/src/split_irqchip_common.rs
@@ -5,6 +5,7 @@
 // Common constants and types used for Split IRQ chip devices (e.g. PIC, PIT, IOAPIC).
 
 use bit_field::*;
+use sys_util::EventFd;
 
 #[bitfield]
 #[derive(Clone, Copy, Debug, PartialEq)]
@@ -58,3 +59,36 @@ pub struct MsiDataMessage {
     trigger: TriggerMode,
     reserved2: BitField16,
 }
+
+/// Acts as a relay of interrupt signals between devices and IRQ chips.
+#[derive(Default)]
+pub struct GsiRelay {
+    pub irqfd: [Option<EventFd>; kvm::NUM_IOAPIC_PINS],
+    pub irqfd_resample: [Option<EventFd>; kvm::NUM_IOAPIC_PINS],
+}
+
+impl GsiRelay {
+    pub fn new() -> GsiRelay {
+        GsiRelay {
+            irqfd: Default::default(),
+            irqfd_resample: Default::default(),
+        }
+    }
+
+    pub fn register_irqfd(&mut self, evt: EventFd, gsi: usize) {
+        if gsi >= kvm::NUM_IOAPIC_PINS {
+            // Invalid gsi; ignore.
+            return;
+        }
+        self.irqfd[gsi] = Some(evt);
+    }
+
+    pub fn register_irqfd_resample(&mut self, evt: EventFd, resample_evt: EventFd, gsi: usize) {
+        if gsi >= kvm::NUM_IOAPIC_PINS {
+            // Invalid gsi; ignore.
+            return;
+        }
+        self.irqfd[gsi] = Some(evt);
+        self.irqfd_resample[gsi] = Some(resample_evt);
+    }
+}