From 1c7997c5c3c0473177f6c4278b9f29896aeb1842 Mon Sep 17 00:00:00 2001
From: Wei Liu <liuwe@microsoft.com>
Date: Fri, 9 Aug 2024 03:24:11 +0000
Subject: [PATCH] hypervisor: x86: emulate MOVSQ

Signed-off-by: Wei Liu <liuwe@microsoft.com>
---
 .../arch/x86/emulator/instructions/movs.rs    | 41 ++++++++++++++++++-
 hypervisor/src/arch/x86/emulator/mod.rs       |  1 +
 2 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/hypervisor/src/arch/x86/emulator/instructions/movs.rs b/hypervisor/src/arch/x86/emulator/instructions/movs.rs
index 330ebce81..f660bd5a7 100644
--- a/hypervisor/src/arch/x86/emulator/instructions/movs.rs
+++ b/hypervisor/src/arch/x86/emulator/instructions/movs.rs
@@ -40,7 +40,7 @@ macro_rules! movs {
             let len = std::mem::size_of::<$bound>();
 
             while count > 0 {
-                let mut memory: [u8; 4] = [0; 4];
+                let mut memory: [u8; 8] = [0; 8];
 
                 let src = state
                     .linearize(Register::DS, rsi, false)
@@ -83,6 +83,11 @@ macro_rules! movs {
     };
 }
 
+pub struct Movsq_m64_m64;
+impl<T: CpuStateManager> InstructionHandler<T> for Movsq_m64_m64 {
+    movs!(u64);
+}
+
 pub struct Movsd_m32_m32;
 impl<T: CpuStateManager> InstructionHandler<T> for Movsd_m32_m32 {
     movs!(u32);
@@ -103,6 +108,40 @@ mod tests {
     use super::*;
     use crate::arch::x86::emulator::mock_vmm::*;
 
+    #[test]
+    fn test_rep_movsq_m64_m64() {
+        let ip: u64 = 0x1000;
+        let memory: [u8; 32] = [
+            0x78, 0x56, 0x34, 0x12, // 0x12345678
+            0xdd, 0xcc, 0xbb, 0xaa, // 0xaabbccdd
+            0xa5, 0x5a, 0xa5, 0x5a, // 0x5aa55aa5
+            0xcd, 0xcd, 0xcd, 0xcd, // 0xcdcdcdcd
+            0x00, 0x00, 0x00, 0x00, // 0x00000000
+            0x00, 0x00, 0x00, 0x00, // 0x00000000
+            0x00, 0x00, 0x00, 0x00, // 0x00000000
+            0x00, 0x00, 0x00, 0x00, // 0x00000000
+        ];
+        let insn = [0xf3, 0x48, 0xa5]; // rep movsq
+        let regs = vec![
+            (Register::ECX, 2),
+            (Register::ESI, 0),
+            (Register::EDI, 0x10),
+        ];
+        let mut data = [0u8; 8];
+
+        let mut vmm = MockVmm::new(ip, regs, Some((0, &memory)));
+
+        assert!(vmm.emulate_first_insn(0, &insn).is_ok());
+
+        vmm.read_memory(0x10, &mut data).unwrap();
+        assert_eq!(0xaabbccdd12345678, <u64>::from_le_bytes(data));
+        vmm.read_memory(0x18, &mut data).unwrap();
+        assert_eq!(0xcdcdcdcd5aa55aa5, <u64>::from_le_bytes(data));
+        // The rest should be default value 0 from MockVmm
+        vmm.read_memory(0x20, &mut data).unwrap();
+        assert_eq!(0x0, <u64>::from_le_bytes(data));
+    }
+
     #[test]
     fn test_rep_movsd_m32_m32() {
         let ip: u64 = 0x1000;
diff --git a/hypervisor/src/arch/x86/emulator/mod.rs b/hypervisor/src/arch/x86/emulator/mod.rs
index 9153aec71..d08ab5b90 100644
--- a/hypervisor/src/arch/x86/emulator/mod.rs
+++ b/hypervisor/src/arch/x86/emulator/mod.rs
@@ -532,6 +532,7 @@ impl<'a, T: CpuStateManager> Emulator<'a, T> {
             (mov, Mov_moffs64_RAX),
             (mov, Mov_RAX_moffs64),
             // MOVS
+            (movs, Movsq_m64_m64),
             (movs, Movsd_m32_m32),
             (movs, Movsw_m16_m16),
             (movs, Movsb_m8_m8),