From 7df80220ec23deec254a4468b57a61a8b3c506c3 Mon Sep 17 00:00:00 2001
From: Anatol Belski <anbelski@linux.microsoft.com>
Date: Tue, 30 May 2023 14:39:57 +0200
Subject: [PATCH] hyperivsor: Add infrastructure to determine CPU vendor

Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
---
 hypervisor/src/cpu.rs        |  9 +++++++++
 hypervisor/src/hypervisor.rs | 32 ++++++++++++++++++++++++++++++++
 hypervisor/src/lib.rs        |  2 ++
 3 files changed, 43 insertions(+)

diff --git a/hypervisor/src/cpu.rs b/hypervisor/src/cpu.rs
index c2fc77057..919e1cc1f 100644
--- a/hypervisor/src/cpu.rs
+++ b/hypervisor/src/cpu.rs
@@ -21,6 +21,15 @@ use crate::MpState;
 use thiserror::Error;
 use vm_memory::GuestAddress;
 
+#[cfg(target_arch = "x86_64")]
+#[derive(Copy, Clone, Default)]
+pub enum CpuVendor {
+    #[default]
+    Unknown,
+    Intel,
+    AMD,
+}
+
 #[derive(Error, Debug)]
 ///
 /// Enum for CPU error
diff --git a/hypervisor/src/hypervisor.rs b/hypervisor/src/hypervisor.rs
index 778ba7b95..1905b85f0 100644
--- a/hypervisor/src/hypervisor.rs
+++ b/hypervisor/src/hypervisor.rs
@@ -9,10 +9,14 @@
 //
 #[cfg(target_arch = "x86_64")]
 use crate::arch::x86::CpuIdEntry;
+#[cfg(target_arch = "x86_64")]
+use crate::cpu::CpuVendor;
 #[cfg(feature = "tdx")]
 use crate::kvm::TdxCapabilities;
 use crate::vm::Vm;
 use crate::HypervisorType;
+#[cfg(target_arch = "x86_64")]
+use std::arch::x86_64;
 use std::sync::Arc;
 use thiserror::Error;
 
@@ -75,6 +79,11 @@ pub enum HypervisorError {
     ///
     #[error("Failed to set partition property:{0}")]
     SetPartitionProperty(#[source] anyhow::Error),
+    ///
+    /// Running on an unsupported CPU
+    ///
+    #[error("Unsupported CPU:{0}")]
+    UnsupportedCpu(#[source] anyhow::Error),
 }
 
 ///
@@ -136,4 +145,27 @@ pub trait Hypervisor: Send + Sync {
 
     /// Get maximum number of vCPUs
     fn get_max_vcpus(&self) -> u32;
+    #[cfg(target_arch = "x86_64")]
+    ///
+    /// Determine CPU vendor
+    ///
+    fn get_cpu_vendor(&self) -> CpuVendor {
+        // SAFETY: call cpuid with valid leaves
+        unsafe {
+            let leaf = x86_64::__cpuid(0x0);
+
+            if leaf.ebx == 0x756e_6547 && leaf.ecx == 0x6c65_746e && leaf.edx == 0x4965_6e69 {
+                // Vendor string GenuineIntel
+                CpuVendor::Intel
+            } else if leaf.ebx == 0x6874_7541 && leaf.ecx == 0x444d_4163 && leaf.edx == 0x6974_6e65
+            {
+                // Vendor string AuthenticAMD
+                CpuVendor::AMD
+            } else {
+                // Not known yet, the corresponding manufacturer manual should contain the
+                // necesssary info. See also https://wiki.osdev.org/CPUID#CPU_Vendor_ID_String
+                CpuVendor::default()
+            }
+        }
+    }
 }
diff --git a/hypervisor/src/lib.rs b/hypervisor/src/lib.rs
index ac15b6511..51c9ff535 100644
--- a/hypervisor/src/lib.rs
+++ b/hypervisor/src/lib.rs
@@ -49,6 +49,8 @@ mod cpu;
 mod device;
 
 pub use crate::hypervisor::{Hypervisor, HypervisorError};
+#[cfg(target_arch = "x86_64")]
+pub use cpu::CpuVendor;
 pub use cpu::{HypervisorCpuError, Vcpu, VmExit};
 pub use device::HypervisorDeviceError;
 #[cfg(all(feature = "kvm", target_arch = "aarch64"))]