alioth 0.12.0

Core library for Alioth, an experimental Type-2 hypervisor.
Documentation 
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// Copyright 2024 Google LLC
//
// 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
//
//     https://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 std::fs::File;
use std::mem::size_of;
use std::os::fd::AsRawFd;
use std::path::Path;
use std::sync::Arc;

use snafu::ResultExt;

use crate::errors::BoxTrace;
use crate::mem::mapped::ArcMemPages;
use crate::mem::{self, LayoutChanged};
use crate::sys::vfio::{
    IommuDestroy, IommuIoasAlloc, IommuIoasMap, IommuIoasMapFlag, IommuIoasUnmap, iommu_destroy,
    iommu_ioas_alloc, iommu_ioas_map, iommu_ioas_unmap,
};
use crate::vfio::{Result, error};

#[derive(Debug)]
pub struct Iommu {
    pub(super) fd: File,
}

impl Iommu {
    pub fn new(path: impl AsRef<Path>) -> Result<Self> {
        let fd = File::open(&path).context(error::AccessDevice {
            path: path.as_ref(),
        })?;
        Ok(Iommu { fd })
    }
}

#[derive(Debug)]
pub struct Ioas {
    pub(super) iommu: Arc<Iommu>,
    pub(super) id: u32,
}

impl Drop for Ioas {
    fn drop(&mut self) {
        if let Err(e) = self.reset() {
            log::error!("Removing mappings from ioas id {:#x}: {e}", self.id)
        }
        let destroy = IommuDestroy {
            size: size_of::<IommuDestroy>() as u32,
            id: self.id,
        };
        let ret = unsafe { iommu_destroy(&self.iommu.fd, &destroy) };
        if let Err(e) = ret {
            log::error!("Destroying ioas id {:#x}: {e}", self.id)
        }
    }
}

impl Ioas {
    pub fn alloc_on(iommu: Arc<Iommu>) -> Result<Self> {
        let mut alloc: IommuIoasAlloc = IommuIoasAlloc {
            size: size_of::<IommuIoasAlloc>() as u32,
            ..Default::default()
        };
        unsafe { iommu_ioas_alloc(&iommu.fd, &mut alloc) }?;
        Ok(Ioas {
            iommu,
            id: alloc.out_ioas_id,
        })
    }

    pub fn map(&self, user_va: usize, iova: u64, len: u64) -> Result<()> {
        let flags =
            IommuIoasMapFlag::READABLE | IommuIoasMapFlag::WRITEABLE | IommuIoasMapFlag::FIXED_IOVA;
        let ioas_map = IommuIoasMap {
            size: size_of::<IommuIoasMap>() as u32,
            flags,
            ioas_id: self.id,
            user_va: user_va as u64,
            length: len,
            iova,
            ..Default::default()
        };
        unsafe { iommu_ioas_map(&self.iommu.fd, &ioas_map) }?;
        log::debug!(
            "ioas-{}-{}: mapped: {iova:#018x} -> {user_va:#018x}, size = {len:#x}",
            self.iommu.fd.as_raw_fd(),
            self.id
        );
        Ok(())
    }

    pub fn unmap(&self, iova: u64, len: u64) -> Result<()> {
        let ioas_unmap = IommuIoasUnmap {
            size: size_of::<IommuIoasUnmap>() as u32,
            ioas_id: self.id,
            iova,
            length: len,
        };
        unsafe { iommu_ioas_unmap(&self.iommu.fd, &ioas_unmap) }?;
        log::debug!(
            "ioas-{}-{}: unmapped: {iova:#018x}, size = {len:#x}",
            self.iommu.fd.as_raw_fd(),
            self.id,
        );
        Ok(())
    }

    pub fn reset(&self) -> Result<()> {
        self.unmap(0, u64::MAX)
    }
}

#[derive(Debug)]
pub struct UpdateIommuIoas {
    pub ioas: Arc<Ioas>,
}

impl LayoutChanged for UpdateIommuIoas {
    fn ram_added(&self, gpa: u64, pages: &ArcMemPages) -> mem::Result<()> {
        let ret = self.ioas.map(pages.addr(), gpa, pages.size());
        ret.box_trace(mem::error::ChangeLayout)?;
        Ok(())
    }

    fn ram_removed(&self, gpa: u64, pages: &ArcMemPages) -> mem::Result<()> {
        let ret = self.ioas.unmap(gpa, pages.size());
        ret.box_trace(mem::error::ChangeLayout)?;
        Ok(())
    }
}