kernel: use cpufeature crate for CET shadow stack detection

Add the cpufeature dependency and implement CpuidBackend for native and
SNP platforms. CET support is now checked via CET_SS instead of manual
CPUID bit masking on both platforms.

Signed-off-by: tanish111 <tanishdesai37@gmail.com>

Author: tanish111

Cargo.lock

@@ -103,6 +103,9 @@ virtio-drivers = { git = "https://github.com/rcore-os/virtio-drivers.git", rev =
 zerocopy = { version = "0.8.2", features = ["derive"] }
 zeroize = { version = "1.8.2", default-features = false }
 
+#Github repos
+cpufeature = { git = "https://github.com/tanish111/cpufeature.git", rev = "4f86e2d062ab8e456566d00db64913caa2f53f33" }
+
 # Verus repos
 verus_builtin = { version = "=0.0.0-2026-04-12-0118", default-features = false }
 verus_builtin_macros = { version = "=0.0.0-2026-04-12-0118", features = ["vpanic"], default-features = false }

Cargo.toml

@@ -16,6 +16,7 @@ doctest = true
 bootdefs.workspace = true
 bootimg.workspace = true
 cpuarch.workspace = true
+cpufeature.workspace = true
 libaproxy = { workspace = true, optional = true }
 elf.workspace = true
 syscall.workspace = true

kernel/Cargo.toml

@@ -1,7 +1,6 @@
 // SPDX-License-Identifier: MIT OR Apache-2.0
 //
 // Copyright (c) Microsoft Corporation
-// Copyright (c) SUSE LLC
 //
 // Author: Jon Lange <jlange@microsoft.com>
 // Author: Joerg Roedel <jroedel@suse.de>
@@ -12,7 +11,6 @@ use super::PageStateChangeOp;
 use super::PageValidateOp;
 use super::SvsmPlatform;
 use super::capabilities::Caps;
-use super::cpuid;
 use crate::address::{PhysAddr, VirtAddr};
 use crate::console::init_svsm_console;
 use crate::cpu::IrqGuard;
@@ -38,6 +36,8 @@ use cpuarch::x86apic::IcrMessageType;
 use bootdefs::kernel_launch::BLDR_BASE;
 use core::arch::asm;
 use core::mem::MaybeUninit;
+use cpufeature::backend::CpuidBackend;
+use cpufeature::leaves::CPU_VENDORID_1;
 use syscall::GlobalFeatureFlags;
 
 #[cfg(debug_assertions)]
@@ -59,6 +59,8 @@ impl NativePlatform {
     }
 }
 
+impl CpuidBackend for NativePlatform {}
+
 impl SvsmPlatform for NativePlatform {
     #[cfg(test)]
     fn platform_type(&self) -> SvsmPlatformType {
@@ -87,14 +89,10 @@ impl SvsmPlatform for NativePlatform {
     }
 
     fn get_cpu_vendor(&self) -> CpuVendor {
-        if let Some(r) = cpuid(0, 0) {
-            match r.edx {
-                0x69746e65 => CpuVendor::AMD,
-                0x49656e69 => CpuVendor::Intel,
-                _ => CpuVendor::Unknown,
-            }
-        } else {
-            CpuVendor::Unknown
+        match Self::cpuid_value(&CPU_VENDORID_1) {
+            Some(0x6974_6e65) => CpuVendor::AMD,
+            Some(0x4965_6e69) => CpuVendor::Intel,
+            _ => CpuVendor::Unknown,
         }
     }
 

kernel/src/platform/native.rs

@@ -58,6 +58,8 @@ use core::arch::x86_64::CpuidResult;
 use core::mem::MaybeUninit;
 use core::ptr;
 use core::sync::atomic::{AtomicU32, Ordering};
+use cpufeature::CpuidFeature;
+use cpufeature::backend::CpuidBackend;
 use syscall::GlobalFeatureFlags;
 
 static GHCB_IO_DRIVER: GHCBIOPort = GHCBIOPort::new();
@@ -296,20 +298,6 @@ impl SvsmPlatform for SnpPlatform {
         })
     }
 
-    fn cpuid(eax: u32, ecx: u32) -> Option<CpuidResult>
-    where
-        Self: Sized,
-    {
-        // If this is an architectural CPUID leaf, then extract the result
-        // from the CPUID table.  Otherwise, request the value from the
-        // hypervisor.
-        if (eax >> 28) == 4 {
-            current_ghcb().cpuid(eax, ecx).ok()
-        } else {
-            cpuid_table(eax, ecx)
-        }
-    }
-
     unsafe fn write_host_msr(&self, msr: u32, value: u64) {
         current_ghcb()
             .wrmsr(msr, value)
@@ -480,6 +468,22 @@ impl SvsmPlatform for SnpPlatform {
     }
 }
 
+impl CpuidBackend for SnpPlatform {
+    fn cpuid(feature: &CpuidFeature) -> Option<CpuidResult>
+    where
+        Self: Sized,
+    {
+        // If this is an architectural CPUID leaf, then extract the result
+        // from the CPUID table.  Otherwise, request the value from the
+        // hypervisor.
+        if (feature.leaf >> 28) == 4 {
+            current_ghcb().cpuid(feature.leaf, feature.subleaf).ok()
+        } else {
+            cpuid_table(feature.leaf, feature.subleaf)
+        }
+    }
+}
+
 #[derive(Clone, Copy, Debug, Default)]
 pub struct GHCBIOPort {}