1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142

// Copyright 2022 The ChromiumOS Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

//! Wraps VfioContainer for virtio-iommu implementation

use std::sync::Arc;

use anyhow::Context;
use base::AsRawDescriptor;
use base::AsRawDescriptors;
use base::Protection;
use base::RawDescriptor;
use sync::Mutex;
use vm_memory::GuestAddress;
use vm_memory::GuestMemory;

use crate::vfio::VfioError;
use crate::virtio::iommu::memory_mapper::AddMapResult;
use crate::virtio::iommu::memory_mapper::MappingInfo;
use crate::virtio::iommu::memory_mapper::MemoryMapper;
use crate::virtio::iommu::memory_mapper::RemoveMapResult;
use crate::VfioContainer;

pub struct VfioWrapper {
    container: Arc<Mutex<VfioContainer>>,
    // ID of the VFIO group which constitutes the container. Note that we rely on
    // the fact that no container contains multiple groups.
    id: u32,
    mem: GuestMemory,
}

impl VfioWrapper {
    pub fn new(container: Arc<Mutex<VfioContainer>>, mem: GuestMemory) -> Self {
        let c = container.lock();
        let groups = c.group_ids();
        // NOTE: vfio_get_container ensures each group gets its own container.
        assert!(groups.len() == 1);
        let id = *groups[0];
        drop(c);
        Self { container, id, mem }
    }

    pub fn new_with_id(container: VfioContainer, id: u32, mem: GuestMemory) -> Self {
        Self {
            container: Arc::new(Mutex::new(container)),
            id,
            mem,
        }
    }

    pub fn clone_as_raw_descriptor(&self) -> Result<RawDescriptor, VfioError> {
        self.container.lock().clone_as_raw_descriptor()
    }

    unsafe fn do_map(&self, map: MappingInfo) -> anyhow::Result<AddMapResult> {
        let res = self.container.lock().vfio_dma_map(
            map.iova,
            map.size,
            map.gpa.offset(),
            map.prot.allows(&Protection::write()),
        );
        if let Err(VfioError::IommuDmaMap(err)) = res {
            if err.errno() == libc::EEXIST {
                // A mapping already exists in the requested range,
                return Ok(AddMapResult::OverlapFailure);
            }
        }
        res.context("vfio mapping error").map(|_| AddMapResult::Ok)
    }
}

impl MemoryMapper for VfioWrapper {
    fn add_map(&mut self, mut map: MappingInfo) -> anyhow::Result<AddMapResult> {
        map.gpa = GuestAddress(
            self.mem
                .get_host_address_range(map.gpa, map.size as usize)
                .context("failed to find host address")? as u64,
        );

        // Safe because both guest and host address are guaranteed by
        // get_host_address_range() to be valid.
        unsafe { self.do_map(map) }
    }

    unsafe fn vfio_dma_map(
        &mut self,
        iova: u64,
        hva: u64,
        size: u64,
        prot: Protection,
    ) -> anyhow::Result<AddMapResult> {
        self.do_map(MappingInfo {
            iova,
            gpa: GuestAddress(hva),
            size,
            prot,
        })
    }

    fn remove_map(&mut self, iova_start: u64, size: u64) -> anyhow::Result<RemoveMapResult> {
        iova_start.checked_add(size).context("iova overflow")?;
        self.container
            .lock()
            .vfio_dma_unmap(iova_start, size)
            .context("vfio unmapping error")
            .map(|_| RemoveMapResult::Success(None))
    }

    fn get_mask(&self) -> anyhow::Result<u64> {
        self.container
            .lock()
            .vfio_get_iommu_page_size_mask()
            .context("vfio get mask error")
    }

    fn supports_detach(&self) -> bool {
        // A few reasons why we don't support detach:
        //
        // 1. Seems it's not possible to dynamically attach and detach a IOMMU domain if the
        //    virtio IOMMU device is running on top of VFIO
        // 2. Even if VIRTIO_IOMMU_T_DETACH is implemented in front-end driver, it could violate
        //    the following virtio IOMMU spec: Detach an endpoint from a domain. when this request
        //    completes, the endpoint cannot access any mapping from that domain anymore.
        //
        //    This is because VFIO doesn't support detaching a single device. When the virtio-iommu
        //    device receives a VIRTIO_IOMMU_T_DETACH request, it can either to:
        //    - detach a group: any other endpoints in the group lose access to the domain.
        //    - do not detach the group at all: this breaks the above mentioned spec.
        false
    }

    fn id(&self) -> u32 {
        self.id
    }
}

impl AsRawDescriptors for VfioWrapper {
    fn as_raw_descriptors(&self) -> Vec<RawDescriptor> {
        vec![self.container.lock().as_raw_descriptor()]
    }
}