Add serde support for various bindings

Add implementations of `serde::{Serialize, Deserialize}` for
kvm-bindings structures commonly used for live migration/snapshotting.
The selections of structures to add the derives to was determined by
finding the minimal set that allows both Firecracker and CloudHypervisor
to compile against this branch.

Signed-off-by: Patrick Roy <roypat@amazon.co.uk>

Cargo.toml

@@ -14,6 +14,11 @@ rustdoc-args = ["--cfg", "docsrs"]
 
 [features]
 fam-wrappers = ["vmm-sys-util"]
+# If the 'fam-wrappers' feature is not enabled, the below 'vmm-sys-util/with-serde' flag will be ignored (e.g. it will not enable the vmm-sys-util dependency). Only if both 'fam-wrappers' and 'with-serde' are enaled is the 'with-serde' feature of vmm-sys-util enabled.
+with-serde = ["dep:serde", "serde/derive", "dep:serde-big-array", "vmm-sys-util/with-serde"]
+
 
 [dependencies]
 vmm-sys-util = { version = "0.12.1", optional = true }
+serde = { version = "1.0.0", optional = true, features = ["derive"] }
+serde-big-array = { version = "0.5.1", optional = true}

src/arm64/bindings.rs

@@ -955,6 +955,7 @@ pub type __wsum = __u32;
 pub type __poll_t = ::std::os::raw::c_uint;
 #[repr(C)]
 #[derive(Debug, Default, Copy, Clone, PartialEq)]
+#[cfg_attr(feature = "with-serde", derive(serde::Deserialize, serde::Serialize))]
 pub struct user_pt_regs {
     pub regs: [__u64; 31usize],
     pub sp: __u64,
@@ -1019,6 +1020,7 @@ fn bindgen_test_layout_user_pt_regs() {
 #[repr(C)]
 #[repr(align(16))]
 #[derive(Debug, Default, Copy, Clone, PartialEq)]
+#[cfg_attr(feature = "with-serde", derive(serde::Deserialize, serde::Serialize))]
 pub struct user_fpsimd_state {
     pub vregs: [__uint128_t; 32usize],
     pub fpsr: __u32,
@@ -1499,6 +1501,7 @@ fn bindgen_test_layout_user_za_header() {
 #[repr(C)]
 #[repr(align(16))]
 #[derive(Debug, Default, Copy, Clone, PartialEq)]
+#[cfg_attr(feature = "with-serde", derive(serde::Deserialize, serde::Serialize))]
 pub struct kvm_regs {
     pub regs: user_pt_regs,
     pub sp_el1: __u64,
@@ -1574,6 +1577,7 @@ fn bindgen_test_layout_kvm_regs() {
 }
 #[repr(C)]
 #[derive(Debug, Default, Copy, Clone, PartialEq)]
+#[cfg_attr(feature = "with-serde", derive(serde::Deserialize, serde::Serialize))]
 pub struct kvm_vcpu_init {
     pub target: __u32,
     pub features: [__u32; 7usize],
@@ -6511,6 +6515,7 @@ fn bindgen_test_layout_kvm_vapic_addr() {
 }
 #[repr(C)]
 #[derive(Debug, Default, Copy, Clone, PartialEq)]
+#[cfg_attr(feature = "with-serde", derive(serde::Deserialize, serde::Serialize))]
 pub struct kvm_mp_state {
     pub mp_state: __u32,
 }
@@ -8786,6 +8791,7 @@ fn bindgen_test_layout_kvm_reg_list() {
 }
 #[repr(C)]
 #[derive(Debug, Default, Copy, Clone, PartialEq)]
+#[cfg_attr(feature = "with-serde", derive(serde::Deserialize, serde::Serialize))]
 pub struct kvm_one_reg {
     pub id: __u64,
     pub addr: __u64,

src/x86_64/bindings.rs

@@ -82,6 +82,7 @@ where
 }
 #[repr(C)]
 #[derive(Default)]
+#[cfg_attr(feature = "with-serde", derive(serde::Deserialize, serde::Serialize))]
 pub struct __IncompleteArrayField<T>(::std::marker::PhantomData<T>, [T; 0]);
 impl<T> __IncompleteArrayField<T> {
     #[inline]
@@ -1426,6 +1427,7 @@ impl ::std::fmt::Debug for kvm_ioapic_state {
 }
 #[repr(C)]
 #[derive(Debug, Default, Copy, Clone, PartialEq)]
+#[cfg_attr(feature = "with-serde", derive(serde::Deserialize, serde::Serialize))]
 pub struct kvm_regs {
     pub rax: __u64,
     pub rbx: __u64,
@@ -1643,7 +1645,9 @@ fn bindgen_test_layout_kvm_regs() {
 }
 #[repr(C)]
 #[derive(Debug, Copy, Clone, PartialEq)]
+#[cfg_attr(feature = "with-serde", derive(serde::Deserialize, serde::Serialize))]
 pub struct kvm_lapic_state {
+    #[cfg_attr(feature = "with-serde", serde(with = "serde_big_array::BigArray"))]
     pub regs: [::std::os::raw::c_char; 1024usize],
 }
 #[test]
@@ -1682,6 +1686,7 @@ impl Default for kvm_lapic_state {
 }
 #[repr(C)]
 #[derive(Debug, Default, Copy, Clone, PartialEq)]
+#[cfg_attr(feature = "with-serde", derive(serde::Deserialize, serde::Serialize))]
 pub struct kvm_segment {
     pub base: __u64,
     pub limit: __u32,
@@ -1844,6 +1849,7 @@ fn bindgen_test_layout_kvm_segment() {
 }
 #[repr(C)]
 #[derive(Debug, Default, Copy, Clone, PartialEq)]
+#[cfg_attr(feature = "with-serde", derive(serde::Deserialize, serde::Serialize))]
 pub struct kvm_dtable {
     pub base: __u64,
     pub limit: __u16,
@@ -1896,6 +1902,7 @@ fn bindgen_test_layout_kvm_dtable() {
 }
 #[repr(C)]
 #[derive(Debug, Default, Copy, Clone, PartialEq)]
+#[cfg_attr(feature = "with-serde", derive(serde::Deserialize, serde::Serialize))]
 pub struct kvm_sregs {
     pub cs: kvm_segment,
     pub ds: kvm_segment,
@@ -2481,6 +2488,7 @@ fn bindgen_test_layout_kvm_fpu() {
 }
 #[repr(C)]
 #[derive(Debug, Default, Copy, Clone, PartialEq)]
+#[cfg_attr(feature = "with-serde", derive(serde::Deserialize, serde::Serialize))]
 pub struct kvm_msr_entry {
     pub index: __u32,
     pub reserved: __u32,
@@ -2533,6 +2541,7 @@ fn bindgen_test_layout_kvm_msr_entry() {
 }
 #[repr(C)]
 #[derive(Debug, Default)]
+#[cfg_attr(feature = "with-serde", derive(serde::Deserialize, serde::Serialize))]
 pub struct kvm_msrs {
     pub nmsrs: __u32,
     pub pad: __u32,
@@ -2885,6 +2894,7 @@ fn bindgen_test_layout_kvm_cpuid() {
 }
 #[repr(C)]
 #[derive(Debug, Default, Copy, Clone, PartialEq)]
+#[cfg_attr(feature = "with-serde", derive(serde::Deserialize, serde::Serialize))]
 pub struct kvm_cpuid_entry2 {
     pub function: __u32,
     pub index: __u32,
@@ -2992,6 +3002,7 @@ fn bindgen_test_layout_kvm_cpuid_entry2() {
 }
 #[repr(C)]
 #[derive(Debug, Default)]
+#[cfg_attr(feature = "with-serde", derive(serde::Deserialize, serde::Serialize))]
 pub struct kvm_cpuid2 {
     pub nent: __u32,
     pub padding: __u32,
@@ -3044,6 +3055,7 @@ fn bindgen_test_layout_kvm_cpuid2() {
 }
 #[repr(C)]
 #[derive(Debug, Default, Copy, Clone, PartialEq)]
+#[cfg_attr(feature = "with-serde", derive(serde::Deserialize, serde::Serialize))]
 pub struct kvm_pit_channel_state {
     pub count: __u32,
     pub latched_count: __u16,
@@ -3341,6 +3353,7 @@ fn bindgen_test_layout_kvm_pit_state() {
 }
 #[repr(C)]
 #[derive(Debug, Default, Copy, Clone, PartialEq)]
+#[cfg_attr(feature = "with-serde", derive(serde::Deserialize, serde::Serialize))]
 pub struct kvm_pit_state2 {
     pub channels: [kvm_pit_channel_state; 3usize],
     pub flags: __u32,
@@ -3434,6 +3447,7 @@ fn bindgen_test_layout_kvm_reinject_control() {
 }
 #[repr(C)]
 #[derive(Debug, Default, Copy, Clone, PartialEq)]
+#[cfg_attr(feature = "with-serde", derive(serde::Deserialize, serde::Serialize))]
 pub struct kvm_vcpu_events {
     pub exception: kvm_vcpu_events__bindgen_ty_1,
     pub interrupt: kvm_vcpu_events__bindgen_ty_2,
@@ -3448,6 +3462,7 @@ pub struct kvm_vcpu_events {
 }
 #[repr(C)]
 #[derive(Debug, Default, Copy, Clone, PartialEq)]
+#[cfg_attr(feature = "with-serde", derive(serde::Deserialize, serde::Serialize))]
 pub struct kvm_vcpu_events__bindgen_ty_1 {
     pub injected: __u8,
     pub nr: __u8,
@@ -3523,6 +3538,7 @@ fn bindgen_test_layout_kvm_vcpu_events__bindgen_ty_1() {
 }
 #[repr(C)]
 #[derive(Debug, Default, Copy, Clone, PartialEq)]
+#[cfg_attr(feature = "with-serde", derive(serde::Deserialize, serde::Serialize))]
 pub struct kvm_vcpu_events__bindgen_ty_2 {
     pub injected: __u8,
     pub nr: __u8,
@@ -3587,6 +3603,7 @@ fn bindgen_test_layout_kvm_vcpu_events__bindgen_ty_2() {
 }
 #[repr(C)]
 #[derive(Debug, Default, Copy, Clone, PartialEq)]
+#[cfg_attr(feature = "with-serde", derive(serde::Deserialize, serde::Serialize))]
 pub struct kvm_vcpu_events__bindgen_ty_3 {
     pub injected: __u8,
     pub pending: __u8,
@@ -3651,6 +3668,7 @@ fn bindgen_test_layout_kvm_vcpu_events__bindgen_ty_3() {
 }
 #[repr(C)]
 #[derive(Debug, Default, Copy, Clone, PartialEq)]
+#[cfg_attr(feature = "with-serde", derive(serde::Deserialize, serde::Serialize))]
 pub struct kvm_vcpu_events__bindgen_ty_4 {
     pub smm: __u8,
     pub pending: __u8,
@@ -3715,6 +3733,7 @@ fn bindgen_test_layout_kvm_vcpu_events__bindgen_ty_4() {
 }
 #[repr(C)]
 #[derive(Debug, Default, Copy, Clone, PartialEq)]
+#[cfg_attr(feature = "with-serde", derive(serde::Deserialize, serde::Serialize))]
 pub struct kvm_vcpu_events__bindgen_ty_5 {
     pub pending: __u8,
 }
@@ -3861,6 +3880,7 @@ fn bindgen_test_layout_kvm_vcpu_events() {
 }
 #[repr(C)]
 #[derive(Debug, Default, Copy, Clone, PartialEq)]
+#[cfg_attr(feature = "with-serde", derive(serde::Deserialize, serde::Serialize))]
 pub struct kvm_debugregs {
     pub db: [__u64; 4usize],
     pub dr6: __u64,
@@ -3935,7 +3955,9 @@ fn bindgen_test_layout_kvm_debugregs() {
 }
 #[repr(C)]
 #[derive(Debug)]
+#[cfg_attr(feature = "with-serde", derive(serde::Deserialize, serde::Serialize))]
 pub struct kvm_xsave {
+    #[cfg_attr(feature = "with-serde", serde(with = "serde_big_array::BigArray"))]
     pub region: [__u32; 1024usize],
     pub extra: __IncompleteArrayField<__u32>,
 }
@@ -3985,6 +4007,7 @@ impl Default for kvm_xsave {
 }
 #[repr(C)]
 #[derive(Debug, Default, Copy, Clone, PartialEq)]
+#[cfg_attr(feature = "with-serde", derive(serde::Deserialize, serde::Serialize))]
 pub struct kvm_xcr {
     pub xcr: __u32,
     pub reserved: __u32,
@@ -4037,6 +4060,7 @@ fn bindgen_test_layout_kvm_xcr() {
 }
 #[repr(C)]
 #[derive(Debug, Default, Copy, Clone, PartialEq)]
+#[cfg_attr(feature = "with-serde", derive(serde::Deserialize, serde::Serialize))]
 pub struct kvm_xcrs {
     pub nr_xcrs: __u32,
     pub flags: __u32,
@@ -5032,6 +5056,7 @@ impl ::std::fmt::Debug for kvm_irq_level {
 }
 #[repr(C)]
 #[derive(Copy, Clone)]
+#[cfg_attr(feature = "with-serde", derive(serde::Deserialize, serde::Serialize))]
 pub struct kvm_irqchip {
     pub chip_id: __u32,
     pub pad: __u32,
@@ -5044,6 +5069,29 @@ pub union kvm_irqchip__bindgen_ty_1 {
     pub pic: kvm_pic_state,
     pub ioapic: kvm_ioapic_state,
 }
+
+#[cfg(feature = "with-serde")]
+impl serde::Serialize for kvm_irqchip__bindgen_ty_1 {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: serde::Serializer,
+    {
+        // SAFETY: Safe because this is a POD struct and we're only using the read result to
+        // serialize the underlying bytes.
+        unsafe { self.dummy.serialize(serializer) }
+    }
+}
+#[cfg(feature = "with-serde")]
+impl<'de> serde::Deserialize<'de> for kvm_irqchip__bindgen_ty_1 {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: serde::Deserializer<'de>,
+    {
+        let dummy = serde_big_array::BigArray::deserialize(deserializer)?;
+        assert_eq!(std::mem::size_of_val(&dummy), std::mem::size_of::<Self>());
+        Ok(Self { dummy })
+    }
+}
 #[test]
 fn bindgen_test_layout_kvm_irqchip__bindgen_ty_1() {
     const UNINIT: ::std::mem::MaybeUninit<kvm_irqchip__bindgen_ty_1> =
@@ -9167,6 +9215,7 @@ fn bindgen_test_layout_kvm_vapic_addr() {
 }
 #[repr(C)]
 #[derive(Debug, Default, Copy, Clone, PartialEq)]
+#[cfg_attr(feature = "with-serde", derive(serde::Deserialize, serde::Serialize))]
 pub struct kvm_mp_state {
     pub mp_state: __u32,
 }
@@ -11404,6 +11453,7 @@ fn bindgen_test_layout_kvm_irqfd() {
 }
 #[repr(C)]
 #[derive(Debug, Default, Copy, Clone, PartialEq)]
+#[cfg_attr(feature = "with-serde", derive(serde::Deserialize, serde::Serialize))]
 pub struct kvm_clock_data {
     pub clock: __u64,
     pub flags: __u32,