From e1a70f676a822a051df207ffede287a81f034277 Mon Sep 17 00:00:00 2001
From: Wei Liu <liuwe@microsoft.com>
Date: Thu, 28 Jul 2022 11:18:08 +0000
Subject: [PATCH] hypervisor: use serde_with with LapicState

Drop the hand-rolled serializer and deserializer.

Signed-off-by: Wei Liu <liuwe@microsoft.com>
---
 Cargo.lock                     | 70 ++++++++++++++++++++++++++++++++++
 hypervisor/Cargo.toml          |  1 +
 hypervisor/src/arch/x86/mod.rs | 27 ++-----------
 3 files changed, 74 insertions(+), 24 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index a8f727ae6..87e2edfbe 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -195,6 +195,41 @@ version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "55626594feae15d266d52440b26ff77de0e22230cf0c113abe619084c1ddc910"
 
+[[package]]
+name = "darling"
+version = "0.14.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4529658bdda7fd6769b8614be250cdcfc3aeb0ee72fe66f9e41e5e5eb73eac02"
+dependencies = [
+ "darling_core",
+ "darling_macro",
+]
+
+[[package]]
+name = "darling_core"
+version = "0.14.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "649c91bc01e8b1eac09fb91e8dbc7d517684ca6be8ebc75bb9cafc894f9fdb6f"
+dependencies = [
+ "fnv",
+ "ident_case",
+ "proc-macro2",
+ "quote",
+ "strsim",
+ "syn",
+]
+
+[[package]]
+name = "darling_macro"
+version = "0.14.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ddfc69c5bfcbd2fc09a0f38451d2daf0e372e367986a83906d1b0dbc88134fb5"
+dependencies = [
+ "darling_core",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "devices"
 version = "0.1.0"
@@ -273,6 +308,12 @@ version = "0.1.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b643857cf70949306b81d7e92cb9d47add673868edac9863c4a49c42feaf3f1e"
 
+[[package]]
+name = "fnv"
+version = "1.0.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3f9eec918d3f24069decb9af1554cad7c880e2da24a9afd88aca000531ab82c1"
+
 [[package]]
 name = "gdbstub"
 version = "0.6.2"
@@ -350,6 +391,7 @@ dependencies = [
  "mshv-bindings",
  "mshv-ioctls",
  "serde",
+ "serde_with",
  "thiserror",
  "vfio-ioctls",
  "vm-memory",
@@ -366,6 +408,12 @@ dependencies = [
  "static_assertions",
 ]
 
+[[package]]
+name = "ident_case"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b9e0384b61958566e926dc50660321d12159025e767c18e043daf26b70104c39"
+
 [[package]]
 name = "indexmap"
 version = "1.9.1"
@@ -939,6 +987,28 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "serde_with"
+version = "2.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "89df7a26519371a3cce44fbb914c2819c84d9b897890987fa3ab096491cc0ea8"
+dependencies = [
+ "serde",
+ "serde_with_macros",
+]
+
+[[package]]
+name = "serde_with_macros"
+version = "2.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "de337f322382fcdfbb21a014f7c224ee041a23785651db67b9827403178f698f"
+dependencies = [
+ "darling",
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "signal-hook"
 version = "0.3.14"
diff --git a/hypervisor/Cargo.toml b/hypervisor/Cargo.toml
index c36d63c4d..416e0ddfa 100644
--- a/hypervisor/Cargo.toml
+++ b/hypervisor/Cargo.toml
@@ -21,6 +21,7 @@ kvm-bindings = { git = "https://github.com/cloud-hypervisor/kvm-bindings", branc
 mshv-bindings = { git = "https://github.com/rust-vmm/mshv", branch = "main", features = ["with-serde", "fam-wrappers"], optional  = true }
 mshv-ioctls = { git = "https://github.com/rust-vmm/mshv", branch = "main", optional  = true}
 serde = { version = "1.0.140", features = ["rc", "derive"] }
+serde_with = { version = "2.0.0", default-features = false, features = ["macros"] }
 vfio-ioctls = { git = "https://github.com/rust-vmm/vfio", branch = "main", default-features = false }
 vm-memory = { version = "0.8.0", features = ["backend-mmap", "backend-atomic"] }
 vmm-sys-util = { version = "0.10.0", features = ["with-serde"] }
diff --git a/hypervisor/src/arch/x86/mod.rs b/hypervisor/src/arch/x86/mod.rs
index 8bf0843cc..79d672284 100644
--- a/hypervisor/src/arch/x86/mod.rs
+++ b/hypervisor/src/arch/x86/mod.rs
@@ -252,8 +252,10 @@ pub struct FpuState {
     pub mxcsr: u32,
 }
 
-#[derive(Debug, Clone)]
+#[serde_with::serde_as]
+#[derive(Debug, Clone, serde::Serialize, serde::Deserialize)]
 pub struct LapicState {
+    #[serde_as(as = "[_; 1024usize]")]
     pub(crate) regs: [::std::os::raw::c_char; 1024usize],
 }
 
@@ -264,29 +266,6 @@ impl Default for LapicState {
     }
 }
 
-impl<'de> serde::Deserialize<'de> for LapicState {
-    fn deserialize<D>(deserializer: D) -> std::result::Result<Self, D::Error>
-    where
-        D: serde::Deserializer<'de>,
-    {
-        let regs: Vec<::std::os::raw::c_char> = Vec::deserialize(deserializer)?;
-        let mut val = LapicState::default();
-        // This panics if the source and destination have different lengths.
-        val.regs.copy_from_slice(&regs[..]);
-        Ok(val)
-    }
-}
-
-impl serde::Serialize for LapicState {
-    fn serialize<S>(&self, serializer: S) -> std::result::Result<S::Ok, S::Error>
-    where
-        S: serde::Serializer,
-    {
-        let regs = &self.regs[..];
-        regs.serialize(serializer)
-    }
-}
-
 impl LapicState {
     pub fn get_klapic_reg(&self, reg_offset: usize) -> u32 {
         use byteorder::{LittleEndian, ReadBytesExt};