fix(vmm): Add vendor ID normalization

The custom CPU template feature allows users to modify vendor ID. This
results in a situation where the vendor ID mismatch the brand string,
because the normalization is enforced on the brand string based on the
host value.

Adds additional normalization on the vendor ID to prevent the above
situation.

Signed-off-by: Takahiro Itazuri <[email protected]>

Author: zulinx86

src/vmm/src/cpu_config/x86_64/cpuid/normalize.rs

@@ -27,6 +27,17 @@ pub enum NormalizeCpuidError {
     /// Failed to set extended cache features leaf.
     #[error("Failed to set extended cache features leaf: {0}")]
     ExtendedCacheFeatures(#[from] ExtendedCacheFeaturesError),
+    /// Failed to set vendor ID in leaf 0x0.
+    #[error("Failed to set vendor ID in leaf 0x0: {0}")]
+    VendorId(#[from] VendorIdError),
+}
+
+/// Error type for setting leaf 0 section.
+#[derive(Debug, thiserror::Error, Eq, PartialEq)]
+pub enum VendorIdError {
+    /// Leaf 0x0 is missing from CPUID.
+    #[error("Leaf 0x0 is missing from CPUID.")]
+    MissingLeaf0,
 }
 
 /// Error type for setting leaf 1 section of `IntelCpuid::normalize`.
@@ -193,6 +204,7 @@ impl super::Cpuid {
         let cpus_per_core = 1u8
             .checked_shl(u32::from(cpu_bits))
             .ok_or(NormalizeCpuidError::CpuBits(cpu_bits))?;
+        self.update_vendor_id()?;
         self.update_feature_info_entry(cpu_index, cpu_count)
             .map_err(NormalizeCpuidError::FeatureInformation)?;
         self.update_extended_topology_entry(cpu_index, cpu_count, cpu_bits, cpus_per_core)
@@ -213,6 +225,22 @@ impl super::Cpuid {
         }
     }
 
+    /// Pass-through the vendor ID from the host. This is used to prevent modification of the vendor
+    /// ID via custom CPU templates.
+    fn update_vendor_id(&mut self) -> Result<(), VendorIdError> {
+        let leaf_0 = self
+            .get_mut(&CpuidKey::leaf(0x0))
+            .ok_or(VendorIdError::MissingLeaf0)?;
+
+        let host_leaf_0 = cpuid(0x0);
+
+        leaf_0.result.ebx = host_leaf_0.ebx;
+        leaf_0.result.ecx = host_leaf_0.ecx;
+        leaf_0.result.edx = host_leaf_0.edx;
+
+        Ok(())
+    }
+
     // Update feature information entry
     fn update_feature_info_entry(
         &mut self,