vmm: cpu: x86: Enable MTRR feature in CPUID

The MTRR feature was missing from the CPUID, which is causing the guest
to ignore the MTRR settings exposed through dedicated MSRs.

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>

vmm/src/cpu.rs

@@ -59,6 +59,8 @@ use vmm_sys_util::signal::{register_signal_handler, SIGRTMIN};
 const TSC_DEADLINE_TIMER_ECX_BIT: u8 = 24; // tsc deadline timer ecx bit.
 #[cfg(target_arch = "x86_64")]
 const HYPERVISOR_ECX_BIT: u8 = 31; // Hypervisor ecx bit.
+#[cfg(target_arch = "x86_64")]
+const MTRR_EDX_BIT: u8 = 12; // Hypervisor ecx bit.
 
 // Debug I/O port
 #[cfg(target_arch = "x86_64")]
@@ -742,6 +744,17 @@ impl CpuManager {
             edx_bit: None,
         });
 
+        // Enable MTRR feature
+        cpuid_patches.push(CpuidPatch {
+            function: 1,
+            index: 0,
+            flags_bit: None,
+            eax_bit: None,
+            ebx_bit: None,
+            ecx_bit: None,
+            edx_bit: Some(MTRR_EDX_BIT),
+        });
+
         // Supported CPUID
         let mut cpuid = hypervisor
             .get_cpuid()