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virtio-devices: Attach and detach endpoints from domain properly

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Properly detach a device from a domain if that device is already
attached to another domain on an attach request (following section
5.13.6.3.2 of the virtio-iommu spec). Resolves nested virtualization
reboot.

Signed-off-by: Andrew Carp <acarp@crusoeenergy.com>
This commit is contained in:
Andrew Carp 2024-03-22 17:33:49 -07:00
parent 3a1f981ff0
commit dbb0d9370b
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1 changed files with 48 additions and 17 deletions
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65
virtio-devices/src/iommu.rs
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@ -407,6 +407,15 @@ impl Request {
let bypass =
(req.flags & VIRTIO_IOMMU_ATTACH_F_BYPASS) == VIRTIO_IOMMU_ATTACH_F_BYPASS;
let mut old_domain_id = domain_id;
if let Some(&id) = mapping.endpoints.read().unwrap().get(&endpoint) {
old_domain_id = id;
}
if old_domain_id != domain_id {
detach_endpoint_from_domain(endpoint, old_domain_id, mapping, ext_mapping)?;
}
// Add endpoint associated with specific domain
mapping
.endpoints
@ -452,22 +461,7 @@ impl Request {
let endpoint = req.endpoint;
// Remove endpoint associated with specific domain
mapping.endpoints.write().unwrap().remove(&endpoint);
// After all endpoints have been successfully detached from a
// domain, the domain can be removed. This means we must remove
// the mappings associated with this domain.
if mapping
.endpoints
.write()
.unwrap()
.iter()
.filter(|(_, &d)| d == domain_id)
.count()
== 0
{
mapping.domains.write().unwrap().remove(&domain_id);
}
detach_endpoint_from_domain(endpoint, domain_id, mapping, ext_mapping)?;
}
VIRTIO_IOMMU_T_MAP => {
if desc_size_left != size_of::<VirtioIommuReqMap>() {
@ -504,7 +498,9 @@ impl Request {
.map(|(&e, _)| e)
.collect();
// Trigger external mapping if necessary.
// For viommu all endpoints receive their own VFIO container, as a result
// Each endpoint within the domain needs to be separately mapped, as the
// mapping is done on a per-container level, not a per-domain level
for endpoint in endpoints {
if let Some(ext_map) = ext_mapping.get(&endpoint) {
let size = req.virt_end - req.virt_start + 1;
@ -653,6 +649,41 @@ impl Request {
}
}
fn detach_endpoint_from_domain(
endpoint: u32,
domain_id: u32,
mapping: &Arc<IommuMapping>,
ext_mapping: &BTreeMap<u32, Arc<dyn ExternalDmaMapping>>,
) -> result::Result<(), Error> {
// Remove endpoint associated with specific domain
mapping.endpoints.write().unwrap().remove(&endpoint);
// Trigger external unmapping for the endpoint if necessary.
if let Some(domain_mappings) = &mapping.domains.read().unwrap().get(&domain_id) {
if let Some(ext_map) = ext_mapping.get(&endpoint) {
for (virt_start, addr_map) in &domain_mappings.mappings {
ext_map
.unmap(*virt_start, addr_map.size)
.map_err(Error::ExternalUnmapping)?;
}
}
}
if mapping
.endpoints
.write()
.unwrap()
.iter()
.filter(|(_, &d)| d == domain_id)
.count()
== 0
{
mapping.domains.write().unwrap().remove(&domain_id);
}
Ok(())
}
struct IommuEpollHandler {
mem: GuestMemoryAtomic<GuestMemoryMmap>,
request_queue: Queue,