vmx_lab 0.1.1

vt-x
Documentation 
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use crate::{x86::controlregs::{Cr4, Xcr0, cr4, cr4_write, xcr0_write}, cputure::GuestRegisters, vmexit::ExitType};

/// Manages the XSETBV instruction during a VM exit. It logs the event, updates
/// CR4 to enable the necessary feature, sets the XCR0 value, and advances the
/// guest's instruction pointer.
///
/// # Arguments
///
/// * `registers` - A mutable reference to the guest VM's general-purpose registers.
///
/// # Returns
///
/// * `ExitType::IncrementRIP` - To move past the `XSETBV` instruction in the VM.
pub fn handle_xsetbv(guest_registers: &mut GuestRegisters) -> ExitType {
    log::trace!("Handling XSETBV VM VM exit...");

    // Extract the XCR (extended control register) number from the guest's RCX register.
    let xcr: u32 = guest_registers.rcx as u32;

    // Combine the guest's RAX and RDX registers to form the 64-bit value for the XCR0 register.
    let value = (guest_registers.rax & 0xffff_ffff) | ((guest_registers.rdx & 0xffff_ffff) << 32);

    // Attempt to create an Xcr0 structure from the given bits.
    let value = Xcr0::from_bits_truncate(value);

    log::trace!("XSETBV executed with xcr: {:#x}, value: {:#x}", xcr, value);

    // Enable the OS XSAVE feature in CR4 before setting the extended control register value.
    cr4_write(cr4() | Cr4::CR4_ENABLE_OS_XSAVE);

    // Write the value to the specified XCR (extended control register).
    xsetbv(value);

    log::trace!("XSETBV VM exit handled successfully!");

    // Advance the guest's instruction pointer to the next instruction to be executed.
    return ExitType::IncrementRIP;
}


pub fn xsetbv(val: Xcr0) {
    xcr0_write(val);
}