hypervisor: Add get_msr_index_list method to the hypervisor trait

CPU profiles will describe a list of MSRs they require when applying
the profile we want to check that the host has all the required MSRs
otherwise we have an incompatibility issue.

In order to check which MSRs the host supports we start by exposing the
hypervisor's get_msr_index_list method.

The MSRs required by a chosen CPU profile will be checked against the
output of the get_msr_index_list and get_feature_msrs on the hypervisor
in a follow up commit.

The get_msr_index_list method does not have an obvious implementation
for MSHV, because in that case one needs to obtain MSR indices from
the VM fd, after the VM has been initialized.

Since CPU profiles are only intended for the KVM hypervisor to begin
with, we leave the MSHV implementation as unimplemented for now. A
proper solution for MSHV should rather be found if/when CPU profiles
are also desired in that context.

Signed-off-by: Oliver Anderson <oliver.anderson@cyberus-technology.de>
On-behalf-of: SAP oliver.anderson@sap.com

hypervisor/src/hypervisor.rs

@@ -146,6 +146,11 @@ pub trait Hypervisor: Send + Sync {
     /// Get feature MSRs supported by the hardware and hypervisor
     ///
     fn get_feature_msrs(&self) -> Result<Vec<MsrEntry>>;
+    #[cfg(target_arch = "x86_64")]
+    ///
+    /// Get the MSR indices supported by the hardware and hypervisor
+    ///
+    fn get_msr_index_list(&self) -> Result<Vec<u32>>;
     ///
     /// Check particular extensions if any
     ///

hypervisor/src/kvm/mod.rs

@@ -1861,6 +1861,11 @@ impl hypervisor::Hypervisor for KvmHypervisor {
         }
     }
 
+    #[cfg(target_arch = "x86_64")]
+    fn get_msr_index_list(&self) -> hypervisor::Result<Vec<u32>> {
+        self.get_msr_list().map(|list| list.as_slice().to_vec())
+    }
+
     #[cfg(target_arch = "aarch64")]
     ///
     /// Retrieve AArch64 host maximum IPA size supported by KVM.

hypervisor/src/mshv/mod.rs

@@ -399,6 +399,12 @@ impl hypervisor::Hypervisor for MshvHypervisor {
         }
         Ok(cpuid)
     }
+
+    #[cfg(target_arch = "x86_64")]
+    fn get_msr_index_list(&self) -> hypervisor::Result<Vec<u32>> {
+        unimplemented!()
+    }
+
     #[cfg(target_arch = "x86_64")]
     fn get_feature_msrs(&self) -> hypervisor::Result<Vec<MsrEntry>> {
         unimplemented!()