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vmm: acpi: Introduce SLIT for NUMA nodes distances

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By introducing the SLIT (System Locality Distance Information Table), we
provide the guest with the distance between each node. This lets the
user describe the NUMA topology with a lot of details so that slower
memory backing the VM can be exposed as being further away from other
nodes.

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This commit is contained in:
Sebastien Boeuf 2020-08-31 15:35:19 +02:00
parent 9548e7e857
commit c0d0d23932
1 changed files with 30 additions and 2 deletions
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32
vmm/src/acpi.rs
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@ -150,12 +150,13 @@ pub fn create_acpi_tables(
.expect("Error writing MCFG table");
tables.push(mcfg_offset.0);
// SRAT
// SRAT and SLIT
// Only created if the NUMA nodes list is not empty.
let numa_nodes = memory_manager.lock().unwrap().numa_nodes().clone();
let (prev_tbl_len, prev_tbl_off) = if numa_nodes.is_empty() {
(mcfg.len(), mcfg_offset)
} else {
// SRAT
let mut srat = SDT::new(*b"SRAT", 36, 3, *b"CLOUDH", *b"CHSRAT ", 1);
// SRAT reserved 12 bytes
srat.append_slice(&[0u8; 12]);
@ -221,7 +222,34 @@ pub fn create_acpi_tables(
.expect("Error writing SRAT table");
tables.push(srat_offset.0);
(srat.len(), srat_offset)
// SLIT
let mut slit = SDT::new(*b"SLIT", 36, 1, *b"CLOUDH", *b"CHSLIT ", 1);
// Number of System Localities on 8 bytes.
slit.append(numa_nodes.len() as u64);
let existing_nodes: Vec<u32> = numa_nodes.keys().cloned().collect();
for (node_id, node) in numa_nodes.iter() {
let distances = node.distances();
for i in existing_nodes.iter() {
let dist: u8 = if *node_id == *i {
10
} else if let Some(distance) = distances.get(i) {
*distance as u8
} else {
20
};
slit.append(dist);
}
}
let slit_offset = srat_offset.checked_add(srat.len() as u64).unwrap();
guest_mem
.write_slice(slit.as_slice(), slit_offset)
.expect("Error writing SRAT table");
tables.push(slit_offset.0);
(slit.len(), slit_offset)
};
// XSDT