kata-containers/cloud-hypervisor
1
0
Fork 0
mirror of https://github.com/cloud-hypervisor/cloud-hypervisor.git synced 2026-08-05 02:19:16 +00:00
Code Issues Packages Projects Releases Wiki Activity

arch: x86_64: handle npot CPU topology

Browse Source 
This PR addresses a bug in which the cpu topology of a guest
with non power-of-two number of cores is incorrect. For example,
in some contexts, a virtual machine with 2-sockets and 12-cores
will incorrectly believe that 16 cores are on socket 1 and 8
cores are on socket 2. In other cases, common topology enumeration
software such as hwloc will crash.

The root of the problem was the way that cloud-hypervisor generates
apic_id. On x86_64, the (x2) apic_id embeds information about cpu
topology. The cpuid instruction is primarily used to discover the
number of sockets, dies, cores, threads, etc. Using this information,
the (x2) apic_id is masked to determine which {core, die, socket} the
cpu is on. When the cpu topology is not a power of two
(e.g. a 12-core machine), this requires non-contiguous (x2) apic_id.

Signed-off-by: Thomas Barrett <tbarrett@crusoeenergy.com>
This commit is contained in:
Thomas Barrett
2023-12-22 03:38:13 +00:00
committed by Rob Bradford
parent a2ceb00fbc
commit 5c0b66529a
6 changed files with 164 additions and 34 deletions
Download Patch File Download Diff File Expand all files Collapse all files
arch/src/x86_64/mptable.rs
+21 -12
View File
@@ -6,7 +6,7 @@
// found in the LICENSE-BSD-3-Clause file.
use crate::layout::{APIC_START, HIGH_RAM_START, IOAPIC_START};
use crate::x86_64::mpspec;
use crate::x86_64::{get_x2apic_id, mpspec};
use crate::GuestMemoryMmap;
use libc::c_char;
use std::mem;
@@ -125,9 +125,18 @@ fn compute_mp_size(num_cpus: u8) -> usize {
}
/// Performs setup of the MP table for the given `num_cpus`.
pub fn setup_mptable(offset: GuestAddress, mem: &GuestMemoryMmap, num_cpus: u8) -> Result<()> {
if num_cpus as u32 > MAX_SUPPORTED_CPUS {
return Err(Error::TooManyCpus);
pub fn setup_mptable(
offset: GuestAddress,
mem: &GuestMemoryMmap,
num_cpus: u8,
topology: Option<(u8, u8, u8)>,
) -> Result<()> {
if num_cpus > 0 {
let cpu_id_max = num_cpus - 1;
let x2apic_id_max = get_x2apic_id(cpu_id_max.into(), topology);
if x2apic_id_max >= MAX_SUPPORTED_CPUS {
return Err(Error::TooManyCpus);
}
}
// Used to keep track of the next base pointer into the MP table.
@@ -141,7 +150,7 @@ pub fn setup_mptable(offset: GuestAddress, mem: &GuestMemoryMmap, num_cpus: u8)
}
let mut checksum: u8 = 0;
let ioapicid: u8 = num_cpus + 1;
let ioapicid: u8 = MAX_SUPPORTED_CPUS as u8 + 1;
// The checked_add here ensures the all of the following base_mp.unchecked_add's will be without
// overflow.
@@ -179,7 +188,7 @@ pub fn setup_mptable(offset: GuestAddress, mem: &GuestMemoryMmap, num_cpus: u8)
for cpu_id in 0..num_cpus {
let mut mpc_cpu = MpcCpuWrapper(mpspec::mpc_cpu::default());
mpc_cpu.0.type_ = mpspec::MP_PROCESSOR as u8;
mpc_cpu.0.apicid = cpu_id;
mpc_cpu.0.apicid = get_x2apic_id(cpu_id as u32, topology) as u8;
mpc_cpu.0.apicver = APIC_VERSION;
mpc_cpu.0.cpuflag = mpspec::CPU_ENABLED as u8
| if cpu_id == 0 {
@@ -312,7 +321,7 @@ mod tests {
let mem =
GuestMemoryMmap::from_ranges(&[(MPTABLE_START, compute_mp_size(num_cpus))]).unwrap();
setup_mptable(MPTABLE_START, &mem, num_cpus).unwrap();
setup_mptable(MPTABLE_START, &mem, num_cpus, None).unwrap();
}
#[test]
@@ -321,7 +330,7 @@ mod tests {
let mem = GuestMemoryMmap::from_ranges(&[(MPTABLE_START, compute_mp_size(num_cpus) - 1)])
.unwrap();
assert!(setup_mptable(MPTABLE_START, &mem, num_cpus).is_err());
assert!(setup_mptable(MPTABLE_START, &mem, num_cpus, None).is_err());
}
#[test]
@@ -330,7 +339,7 @@ mod tests {
let mem =
GuestMemoryMmap::from_ranges(&[(MPTABLE_START, compute_mp_size(num_cpus))]).unwrap();
setup_mptable(MPTABLE_START, &mem, num_cpus).unwrap();
setup_mptable(MPTABLE_START, &mem, num_cpus, None).unwrap();
let mpf_intel: MpfIntelWrapper = mem.read_obj(MPTABLE_START).unwrap();
@@ -346,7 +355,7 @@ mod tests {
let mem =
GuestMemoryMmap::from_ranges(&[(MPTABLE_START, compute_mp_size(num_cpus))]).unwrap();
setup_mptable(MPTABLE_START, &mem, num_cpus).unwrap();
setup_mptable(MPTABLE_START, &mem, num_cpus, None).unwrap();
let mpf_intel: MpfIntelWrapper = mem.read_obj(MPTABLE_START).unwrap();
let mpc_offset = GuestAddress(mpf_intel.0.physptr as GuestUsize);
@@ -384,7 +393,7 @@ mod tests {
.unwrap();
for i in 0..MAX_SUPPORTED_CPUS as u8 {
setup_mptable(MPTABLE_START, &mem, i).unwrap();
setup_mptable(MPTABLE_START, &mem, i, None).unwrap();
let mpf_intel: MpfIntelWrapper = mem.read_obj(MPTABLE_START).unwrap();
let mpc_offset = GuestAddress(mpf_intel.0.physptr as GuestUsize);
@@ -417,7 +426,7 @@ mod tests {
let mem =
GuestMemoryMmap::from_ranges(&[(MPTABLE_START, compute_mp_size(cpus as u8))]).unwrap();
let result = setup_mptable(MPTABLE_START, &mem, cpus as u8);
let result = setup_mptable(MPTABLE_START, &mem, cpus as u8, None);
assert!(result.is_err());
}
}