x86: pass through cpuid leaves 15h and 16h

CHANGELOG.md

@@ -21,6 +21,9 @@ and this project adheres to
   so users need to regenerate snapshots.
 - [#4731](https://github.com/firecracker-microvm/firecracker/pull/4731): Added
   support for modifying the host TAP device name during snapshot restore.
+- [#5186](https://github.com/firecracker-microvm/firecracker/pull/5186): Pass
+  through CPUID leaves 15h and 16h on Intel CPUs (Crystal clock, processor, and
+  and bus frequencies).
 
 ### Changed
 

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

@@ -5,7 +5,7 @@
     CheckedAssignError, get_range, set_bit, set_range,
 };
 use crate::cpu_config::x86_64::cpuid::{
-    BRAND_STRING_LENGTH, CpuidKey, CpuidRegisters, CpuidTrait, MissingBrandStringLeaves,
+    BRAND_STRING_LENGTH, CpuidKey, CpuidRegisters, CpuidTrait, MissingBrandStringLeaves, cpuid,
     host_brand_string,
 };
 
@@ -14,12 +14,8 @@
 pub enum NormalizeCpuidError {
     /// Failed to set deterministic cache leaf: {0}
     DeterministicCache(#[from] DeterministicCacheError),
-    /// Leaf 0x6 is missing from CPUID.
-    MissingLeaf6,
-    /// Leaf 0x7 / subleaf 0 is missing from CPUID.
-    MissingLeaf7,
-    /// Leaf 0xA is missing from CPUID.
-    MissingLeafA,
+    /// Leaf {0} is missing from CPUID.
+    MissingLeaf(usize),
     /// Failed to get brand string: {0}
     GetBrandString(DefaultBrandStringError),
     /// Failed to set brand string: {0}
@@ -75,10 +71,53 @@
         self.update_performance_monitoring_entry()?;
         self.update_extended_topology_v2_entry();
         self.update_brand_string_entry()?;
+        self.update_frequency_information();
 
         Ok(())
     }
 
+    /// Passes through the host value of cpuid leaves 15h and 16h if they
+    /// are not already configured via cpu template.
+    fn update_frequency_information(&mut self) {
+        let Some(leaf_15h) = self.get_mut(&CpuidKey::leaf(0x15)) else {
+            return;
+        };
+
+        if leaf_15h.result == CpuidRegisters::default() {
+            let host_leaf_15 = cpuid(0x15);
+
+            // CPUID.15H:EAX[31:0]
+            // Ratio of TSC frequency to Core Crystal Clock frequency, denominator
+            leaf_15h.result.eax = host_leaf_15.eax;
+            // CPUID.15H:EBX[31:0]
+            // Ratio of TSC frequency to Core Crystal Clock frequency, numerator
+            leaf_15h.result.ebx = host_leaf_15.ebx;
+            // CPUID.15H:ECX[31:0]
+            // Core Crystal Clock frequency, in units of Hz
+            leaf_15h.result.ecx = host_leaf_15.ecx;
+            // edx is reserved
+        }
+
+        let Some(leaf_16h) = self.get_mut(&CpuidKey::leaf(0x16)) else {
+            return;
+        };
+
+        if leaf_16h.result == CpuidRegisters::default() {
+            let host_leaf_16 = cpuid(0x16);
+
+            // CPUID.16H:EAX[15:0]
+            // Processor Base Frequency (in MHz)
+            leaf_16h.result.eax = host_leaf_16.eax;
+            // CPUID.16H:EBX[15:0]
+            // Processor Maximum Frequency (in MHz)
+            leaf_16h.result.ebx = host_leaf_16.ebx;
+            // CPUID.16H:ECX[15:0]
+            // Bus/Reference frequency (in MHz)
+            leaf_16h.result.ecx = host_leaf_16.ecx;
+            // edx is reserved
+        }
+    }
+
     /// Update deterministic cache entry
     #[allow(clippy::unwrap_in_result)]
     fn update_deterministic_cache_entry(
@@ -164,7 +203,7 @@
     fn update_power_management_entry(&mut self) -> Result<(), NormalizeCpuidError> {
         let leaf_6 = self
             .get_mut(&CpuidKey::leaf(0x6))
-            .ok_or(NormalizeCpuidError::MissingLeaf6)?;
+            .ok_or(NormalizeCpuidError::MissingLeaf(6))?;
 
         // CPUID.06H:EAX[1]
         // Intel Turbo Boost Technology available (see description of IA32_MISC_ENABLE[38]).
@@ -184,7 +223,7 @@
     fn update_extended_feature_flags_entry(&mut self) -> Result<(), NormalizeCpuidError> {
         let leaf_7_0 = self
             .get_mut(&CpuidKey::subleaf(0x7, 0))
-            .ok_or(NormalizeCpuidError::MissingLeaf7)?;
+            .ok_or(NormalizeCpuidError::MissingLeaf(7))?;
 
         // Set the following bits as recommended in kernel doc. These bits are reserved in AMD.
         // - CPUID.07H:EBX[6] (FDP_EXCPTN_ONLY)
@@ -243,7 +282,7 @@
     fn update_performance_monitoring_entry(&mut self) -> Result<(), NormalizeCpuidError> {
         let leaf_a = self
             .get_mut(&CpuidKey::leaf(0xA))
-            .ok_or(NormalizeCpuidError::MissingLeafA)?;
+            .ok_or(NormalizeCpuidError::MissingLeaf(0xA))?;
         leaf_a.result = CpuidRegisters {
             eax: 0,
             ebx: 0,