crosvm: support kvm's hyper-v cpuid ioctl

Kvm can emulate the hyper-v paravirt interface.  Newer versions of kvm
can advertise the features they support via an ioctl() that reports the
cpuid leafs for this interface.  This change adds some support for the
ioctl() and plumbs it through the plugin interface so that plugins can
determine the level of support available in kvm.

BUG=b:144746965
TEST=Ran build_test on kernel that supports the ioctl.  Added temporary
code to print the cpuid leafs and verified that the output is as
expected.  Instrumented failure as expected from older kernels and
verified that results still passed.

Change-Id: I6cd7dade1793e4edb52b331d5b960685541f7ba3
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/2037919
Tested-by: Matt Delco <delco@chromium.org>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Daniel Verkamp <dverkamp@chromium.org>
Commit-Queue: Matt Delco <delco@chromium.org>

1 files changed, 11 insertions, 0 deletions

diff --git a/src/plugin/vcpu.rs b/src/plugin/vcpu.rs
index c623bda..6bae9c4 100644
--- a/src/plugin/vcpu.rs
+++ b/src/plugin/vcpu.rs
@@ -595,6 +595,17 @@ impl PluginVcpu {
                 response.mut_set_state();
                 let set_state = request.get_set_state();
                 set_vcpu_state(vcpu, set_state.set, set_state.get_state())
+            } else if request.has_get_hyperv_cpuid() {
+                let cpuid_response = &mut response.mut_get_hyperv_cpuid().entries;
+                match vcpu.get_hyperv_cpuid() {
+                    Ok(mut cpuid) => {
+                        for entry in cpuid.mut_entries_slice() {
+                            cpuid_response.push(cpuid_kvm_to_proto(entry));
+                        }
+                        Ok(())
+                    }
+                    Err(e) => Err(e),
+                }
             } else if request.has_get_msrs() {
                 let entry_data = &mut response.mut_get_msrs().entry_data;
                 let entry_indices = &request.get_get_msrs().entry_indices;