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virtio-devices: save pci configuration capability state in snapshot

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When restoring a VM, the VirtioPciCfgCapInfo struct is not properly
initialized. All fields are 0, including the offset where the
capabibility starts. Hence, when you read a PCI configuration register
in the range [0..length(VirtioPciCfgCap)] you get the value 0 instead of
the actual register contents.

Linux rescans the whole PCI bus when adding a new device. It reads the
values vendor_id and device_id for every device. Because these are
stored at offset 0 in pci configuration space, their value is 0 for
existing devices.  As such, Linux considers that the devices have been
unplugged and it removes them from the system.

Fixes: #6265

Signed-off-by: Alexandru Matei <alexandru.matei@uipath.com>
This commit is contained in:
Alexandru Matei 2024-03-22 13:49:08 +02:00 committed by Rob Bradford
parent 58e6a289ab
commit c3f1c3ee3d
1 changed files with 15 additions and 4 deletions
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19
virtio-devices/src/transport/pci_device.rs
View File

@ -278,6 +278,8 @@ pub struct VirtioPciDeviceState {
device_activated: bool,
queues: Vec<QueueState>,
interrupt_status: usize,
cap_pci_cfg_offset: usize,
cap_pci_cfg: Vec<u8>,
}
impl VersionMapped for VirtioPciDeviceState {}
@ -530,7 +532,7 @@ impl VirtioPciDevice {
))
})?;
let (device_activated, interrupt_status) = if let Some(state) = state {
let (device_activated, interrupt_status, cap_pci_cfg_info) = if let Some(state) = state {
// Update virtqueues indexes for both available and used rings.
for (i, queue) in queues.iter_mut().enumerate() {
queue.set_size(state.queues[i].size);
@ -558,9 +560,16 @@ impl VirtioPciDevice {
);
}
(state.device_activated, state.interrupt_status)
(
state.device_activated,
state.interrupt_status,
VirtioPciCfgCapInfo {
offset: state.cap_pci_cfg_offset,
cap: *VirtioPciCfgCap::from_slice(&state.cap_pci_cfg).unwrap(),
},
)
} else {
(false, 0)
(false, 0, VirtioPciCfgCapInfo::default())
};
// Dropping the MutexGuard to unlock the VirtioDevice. This is required
@ -585,7 +594,7 @@ impl VirtioPciDevice {
settings_bar: 0,
use_64bit_bar,
interrupt_source_group,
cap_pci_cfg_info: VirtioPciCfgCapInfo::default(),
cap_pci_cfg_info,
bar_regions: vec![],
activate_evt,
dma_handler,
@ -634,6 +643,8 @@ impl VirtioPciDevice {
used_ring: q.used_ring(),
})
.collect(),
cap_pci_cfg_offset: self.cap_pci_cfg_info.offset,
cap_pci_cfg: self.cap_pci_cfg_info.cap.bytes().to_vec(),
}
}