Start render node host service in crosvm

BUG=b:118408510
TEST=manual - build crosvm with/without crosvm-gpu-forward USE flag and run arcvm.

Change-Id: Ibb85d52dc679aa8524b29d86148ca28d82d8fe98
Reviewed-on: https://chromium-review.googlesource.com/1347330
Commit-Ready: Lepton Wu <lepton@chromium.org>
Tested-by: Lepton Wu <lepton@chromium.org>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Lepton Wu <lepton@chromium.org>
Reviewed-by: Zach Reizner <zachr@chromium.org>

2 files changed, 72 insertions, 0 deletions

diff --git a/render_node_forward/Cargo.toml b/render_node_forward/Cargo.toml
new file mode 100644
index 0000000..accd36d
--- /dev/null
+++ b/render_node_forward/Cargo.toml
@@ -0,0 +1,10 @@
+[package]
+name = "render_node_forward"
+version = "0.1.0"
+authors = ["The Chromium OS Authors"]
+
+[lib]
+path = "lib.rs"
+
+[dependencies]
+sys_util = { path = "../sys_util" }
diff --git a/render_node_forward/lib.rs b/render_node_forward/lib.rs
new file mode 100644
index 0000000..8c04eb9
--- /dev/null
+++ b/render_node_forward/lib.rs
@@ -0,0 +1,62 @@
+// Copyright 2019 The Chromium OS Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+extern crate sys_util;
+
+use sys_util::{GuestAddress, GuestMemory, MemoryMapping};
+
+#[link(name = "rendernodehost")]
+extern "C" {
+    fn start_render_node_host(
+        gpu_host_mem: *mut u8,
+        gpu_guest_mem_start: u64,
+        gpu_guest_mem_size: u64,
+        host_start: *const u8,
+        host_4g_start: *const u8,
+    );
+}
+
+/// The number of bytes in 4 GiB.
+pub const FOUR_GB: u64 = (1 << 32);
+/// The size required for the render node host in host and guest address space.
+pub const RENDER_NODE_HOST_SIZE: u64 = FOUR_GB;
+
+/// A render node host device that interfaces with the guest render node forwarder.
+pub struct RenderNodeHost {
+    #[allow(dead_code)]
+    guest_mem: GuestMemory,
+}
+
+impl RenderNodeHost {
+    /// Starts the render node host forwarding service over the given guest and host address ranges.
+    pub fn start(
+        mmap: &MemoryMapping,
+        gpu_guest_address: u64,
+        guest_mem: GuestMemory,
+    ) -> RenderNodeHost {
+        // Render node forward library need to do address translation between host user space
+        // address and guest physical address. We could call Rust function from C library. But
+        // since it's actually a linear mapping now, we just pass the host start address to
+        // render node forward library. We need two start address here since there would be a
+        // hole below 4G if guest memory size is bigger than 4G.
+
+        let host_start_addr = guest_mem.get_host_address(GuestAddress(0)).unwrap();
+        let host_4g_addr = if guest_mem.memory_size() > FOUR_GB {
+            guest_mem.get_host_address(GuestAddress(FOUR_GB)).unwrap()
+        } else {
+            host_start_addr
+        };
+        // Safe because only valid addresses are given.
+        unsafe {
+            start_render_node_host(
+                mmap.as_ptr(),
+                gpu_guest_address,
+                mmap.size() as u64,
+                host_start_addr,
+                host_4g_addr,
+            )
+        }
+        RenderNodeHost { guest_mem }
+    }
+}