features.rs

// SPDX-License-Identifier: MIT OR Apache-2.0
//
// Copyright (c) 2022-2023, 2026 SUSE LLC
//
// Authors: Joerg Roedel <jroedel@suse.de>
//          Carlos López <clopez@suse.de>

use crate::platform::cpuid;
use cpufeature::CpuidFeature;
use cpufeature::CpuidRegister;

/// Raw EAX from CPUID leaf 0x8000_0008 — processor capacity parameters.
pub const PHYS_ADDR_SIZES: CpuidFeature = CpuidFeature {
    leaf: 0x8000_0008,
    subleaf: 0,
    register: CpuidRegister::Eax,
    shift: 0,
    width: 32,
};

/// CPUID.4000_0001:EAX — Hyper-V interface signature ("Hv#1").
pub const HYPERV_INTERFACE: CpuidFeature = CpuidFeature {
    leaf: 0x4000_0001,
    subleaf: 0,
    register: CpuidRegister::Eax,
    shift: 0,
    width: 32,
};

const HYPERV_INTERFACE_SIGNATURE: u32 = 0x3123_7648;

fn cpuid_field(feature: &CpuidFeature) -> Option<u32> {
    cpuid(feature).map(|regs| {
        let raw = feature
            .register
            .select(regs.eax, regs.ebx, regs.ecx, regs.edx);
        let mask = ((1u64 << feature.width) as u32).wrapping_sub(1);
        (raw >> feature.shift) & mask
    })
}

/// Check if the given feature is enabled by comparing it to its expected
/// value.
pub fn cpu_has_feat(feature: &CpuidFeature) -> bool {
    if core::ptr::eq(feature, &HYPERV_INTERFACE) {
        cpuid_field(feature) == Some(HYPERV_INTERFACE_SIGNATURE)
    } else {
        cpuid_field(feature) == Some(1)
    }
}

/// Gets the raw value of the given feature.
pub fn cpu_get_feat(feature: &CpuidFeature) -> u32 {
    cpuid_field(feature).unwrap_or(0)
}