ax-cpu 0.10.0

Privileged instruction and structure abstractions for various CPU architectures
Documentation 
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// Copyright 2025 The Axvisor Team
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

use core::mem::offset_of;

use super::super::virtualization::context::{GuestCpuState, HypervisorCpuState, Vcpu};
use crate::registers::{FpState, GprIndex};

const fn hyp_gpr_offset(index: GprIndex) -> usize {
    offset_of!(Vcpu, hyp_regs) + offset_of!(HypervisorCpuState, gprs) + index.byte_offset()
}

const fn guest_gpr_offset(index: GprIndex) -> usize {
    offset_of!(Vcpu, guest_regs) + offset_of!(GuestCpuState, gprs) + index.byte_offset()
}

macro_rules! hyp_csr_offset {
    ($reg:tt) => {
        offset_of!(Vcpu, hyp_regs) + offset_of!(HypervisorCpuState, $reg)
    };
}

macro_rules! guest_csr_offset {
    ($reg:tt) => {
        offset_of!(Vcpu, guest_regs) + offset_of!(GuestCpuState, $reg)
    };
}

core::arch::global_asm!(
    include_fp_asm_macros!(),
    include_str!("guest.S"),
    trap_pc = const offset_of!(Vcpu, trap_csrs) + offset_of!(super::super::virtualization::context::Exit, pc),
    guest_fp = const offset_of!(Vcpu, fp),
    host_fp = const offset_of!(Vcpu, host_fp),
    fcsr = const offset_of!(FpState, fcsr),
    trap_scause = const offset_of!(Vcpu, trap_csrs) + offset_of!(super::super::virtualization::context::Exit, scause),
    trap_stval = const offset_of!(Vcpu, trap_csrs) + offset_of!(super::super::virtualization::context::Exit, stval),
    trap_htval = const offset_of!(Vcpu, trap_csrs) + offset_of!(super::super::virtualization::context::Exit, htval),
    trap_htinst = const offset_of!(Vcpu, trap_csrs) + offset_of!(super::super::virtualization::context::Exit, htinst),

    hyp_ra = const hyp_gpr_offset(GprIndex::RA),
    hyp_gp = const hyp_gpr_offset(GprIndex::GP),
    hyp_tp = const hyp_gpr_offset(GprIndex::TP),
    hyp_s0 = const hyp_gpr_offset(GprIndex::S0),
    hyp_s1 = const hyp_gpr_offset(GprIndex::S1),
    // hyp_a0 = const hyp_gpr_offset(GprIndex::A0),
    hyp_a1 = const hyp_gpr_offset(GprIndex::A1),
    hyp_a2 = const hyp_gpr_offset(GprIndex::A2),
    hyp_a3 = const hyp_gpr_offset(GprIndex::A3),
    hyp_a4 = const hyp_gpr_offset(GprIndex::A4),
    hyp_a5 = const hyp_gpr_offset(GprIndex::A5),
    hyp_a6 = const hyp_gpr_offset(GprIndex::A6),
    hyp_a7 = const hyp_gpr_offset(GprIndex::A7),
    hyp_s2 = const hyp_gpr_offset(GprIndex::S2),
    hyp_s3 = const hyp_gpr_offset(GprIndex::S3),
    hyp_s4 = const hyp_gpr_offset(GprIndex::S4),
    hyp_s5 = const hyp_gpr_offset(GprIndex::S5),
    hyp_s6 = const hyp_gpr_offset(GprIndex::S6),
    hyp_s7 = const hyp_gpr_offset(GprIndex::S7),
    hyp_s8 = const hyp_gpr_offset(GprIndex::S8),
    hyp_s9 = const hyp_gpr_offset(GprIndex::S9),
    hyp_s10 = const hyp_gpr_offset(GprIndex::S10),
    hyp_s11 = const hyp_gpr_offset(GprIndex::S11),
    hyp_sp = const hyp_gpr_offset(GprIndex::SP),
    hyp_sstatus = const hyp_csr_offset!(sstatus),
    hyp_hstatus = const hyp_csr_offset!(hstatus),
    hyp_scounteren = const hyp_csr_offset!(scounteren),
    hyp_stvec = const hyp_csr_offset!(stvec),
    hyp_sscratch = const hyp_csr_offset!(sscratch),
    guest_ra = const guest_gpr_offset(GprIndex::RA),
    guest_gp = const guest_gpr_offset(GprIndex::GP),
    guest_tp = const guest_gpr_offset(GprIndex::TP),
    guest_s0 = const guest_gpr_offset(GprIndex::S0),
    guest_s1 = const guest_gpr_offset(GprIndex::S1),
    guest_a0 = const guest_gpr_offset(GprIndex::A0),
    guest_a1 = const guest_gpr_offset(GprIndex::A1),
    guest_a2 = const guest_gpr_offset(GprIndex::A2),
    guest_a3 = const guest_gpr_offset(GprIndex::A3),
    guest_a4 = const guest_gpr_offset(GprIndex::A4),
    guest_a5 = const guest_gpr_offset(GprIndex::A5),
    guest_a6 = const guest_gpr_offset(GprIndex::A6),
    guest_a7 = const guest_gpr_offset(GprIndex::A7),
    guest_s2 = const guest_gpr_offset(GprIndex::S2),
    guest_s3 = const guest_gpr_offset(GprIndex::S3),
    guest_s4 = const guest_gpr_offset(GprIndex::S4),
    guest_s5 = const guest_gpr_offset(GprIndex::S5),
    guest_s6 = const guest_gpr_offset(GprIndex::S6),
    guest_s7 = const guest_gpr_offset(GprIndex::S7),
    guest_s8 = const guest_gpr_offset(GprIndex::S8),
    guest_s9 = const guest_gpr_offset(GprIndex::S9),
    guest_s10 = const guest_gpr_offset(GprIndex::S10),
    guest_s11 = const guest_gpr_offset(GprIndex::S11),
    guest_t0 = const guest_gpr_offset(GprIndex::T0),
    guest_t1 = const guest_gpr_offset(GprIndex::T1),
    guest_t2 = const guest_gpr_offset(GprIndex::T2),
    guest_t3 = const guest_gpr_offset(GprIndex::T3),
    guest_t4 = const guest_gpr_offset(GprIndex::T4),
    guest_t5 = const guest_gpr_offset(GprIndex::T5),
    guest_t6 = const guest_gpr_offset(GprIndex::T6),
    guest_sp = const guest_gpr_offset(GprIndex::SP),

    guest_sstatus = const guest_csr_offset!(sstatus),
    guest_hstatus = const guest_csr_offset!(hstatus),
    guest_scounteren = const guest_csr_offset!(scounteren),
    guest_sepc = const guest_csr_offset!(sepc),
);

unsafe extern "C" {
    fn __ax_cpu_riscv_run_guest(state: *mut Vcpu);
}

/// Enters the guest and restores host integer, floating-point and CSR state.
///
/// # Safety
/// The caller must own this hart's H extension and bound VS CSR bank, keep
/// interrupts disabled, and provide valid guest translation and delegation.
/// The register image must remain exclusively accessible for the complete
/// call. The target must implement the F/D extensions used by this image.
/// Guest memory must not permit modifying host code, page tables or this image.
/// Host trap, stack, TLS and scratch bindings must be valid for restoration.
pub unsafe fn enter_guest(registers: &mut Vcpu) -> super::super::virtualization::context::Exit {
    // SAFETY: the caller owns all machine state consumed by this transaction.
    // Assembly restores host FP, TLS and CSR state before any Rust runs again.
    unsafe {
        super::super::virtualization::invalidate_gstage_translations();
        __ax_cpu_riscv_run_guest(registers);
    }
    registers.trap_csrs
}