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vmm: More specific CPU model check for CPU templates
Do CPU model check for static CPU templates in accordance with the doc change in the prev commit. Signed-off-by: Takahiro Itazuri <[email protected]>
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6 files changed

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‎CHANGELOG.md‎

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@@ -26,6 +26,10 @@ and this project adheres to
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WAITPKG CPUID bit in CPUID normalization. The feature enables a guest to put a
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physical processor into an idle state, which is undesirable in a FaaS
2828
environment since that is what the host wants to decide.
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- [#5142](https://github.com/firecracker-microvm/firecracker/pull/5142):
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Clarified what CPU models are supported by each existing CPU template.
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Firecracker exits with an error if a CPU template is used on an unsupported
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CPU model.
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### Deprecated
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‎docs/cpu_templates/cpu-templates.md‎

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@@ -48,14 +48,14 @@ Firecracker supports two types of CPU templates:
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At the moment the following set of static CPU templates are supported:
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51-
| CPU template | CPU vendor | CPU model |
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| ------------ | ---------- | --------------------- |
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| C3 | Intel | any |
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| T2 | Intel | any |
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| T2A | AMD | Milan |
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| T2CL | Intel | Cascade Lake or newer |
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| T2S | Intel | any |
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| V1N1 | ARM | Neoverse V1 |
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| CPU template | CPU vendor | CPU model |
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| ------------ | ---------- | ------------------------------- |
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| C3 | Intel | Skylake, Cascade Lake, Ice Lake |
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| T2 | Intel | Skylake, Cascade Lake, Ice Lake |
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| T2A | AMD | Milan |
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| T2CL | Intel | Cascade Lake, Ice Lake |
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| T2S | Intel | Skylake, Cascade Lake |
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| V1N1 | ARM | Neoverse V1 |
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T2 and C3 templates are mapped as close as possible to AWS T2 and C3 instances
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in terms of CPU features. Note that on a microVM that is lauched with the C3
@@ -72,7 +72,7 @@ Firecracker expects the host to always be running the latest version of the
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microcode.
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The T2CL template is mapped to be close to Intel Cascade Lake. It is not safe to
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use it on Intel CPUs older than Cascade Lake (such as Skylake).
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use it on Intel CPUs other than Cascade Lake and Ice Lake.
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The only AMD template is T2A. It is considered safe to be used with AMD Milan.
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‎src/vmm/src/arch/x86_64/cpu_model.rs‎

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Original file line numberDiff line numberDiff line change
@@ -2,7 +2,7 @@
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// SPDX-License-Identifier: Apache-2.0
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use std::arch::x86_64::__cpuid as host_cpuid;
5-
use std::cmp::{Eq, Ordering, PartialEq, PartialOrd};
5+
use std::cmp::{Eq, PartialEq};
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/// Structure representing x86_64 CPU model.
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#[derive(Debug, Eq, PartialEq)]
@@ -19,6 +19,42 @@ pub struct CpuModel {
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pub stepping: u8,
2020
}
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22+
/// Family / Model / Stepping for Intel Skylake
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pub const SKYLAKE_FMS: CpuModel = CpuModel {
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extended_family: 0x0,
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extended_model: 0x5,
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family: 0x6,
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model: 0x5,
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stepping: 0x4,
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};
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31+
/// Family / Model / Stepping for Intel Cascade Lake
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pub const CASCADE_LAKE_FMS: CpuModel = CpuModel {
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extended_family: 0x0,
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extended_model: 0x5,
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family: 0x6,
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model: 0x5,
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stepping: 0x7,
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};
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/// Family / Model / Stepping for Intel Ice Lake
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pub const ICE_LAKE_FMS: CpuModel = CpuModel {
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extended_family: 0x0,
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extended_model: 0x6,
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family: 0x6,
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model: 0xa,
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stepping: 0x6,
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};
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/// Family / Model / Stepping for AMD Milan
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pub const MILAN_FMS: CpuModel = CpuModel {
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extended_family: 0xa,
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extended_model: 0x0,
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family: 0xf,
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model: 0x1,
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stepping: 0x1,
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};
57+
2258
impl CpuModel {
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/// Get CPU model from current machine.
2460
pub fn get_cpu_model() -> Self {
@@ -27,19 +63,6 @@ impl CpuModel {
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let eax = unsafe { host_cpuid(0x1) }.eax;
2864
CpuModel::from(&eax)
2965
}
30-
31-
/// Check if the current CPU model is Intel Cascade Lake or later.
32-
pub fn is_at_least_cascade_lake(&self) -> bool {
33-
let cascade_lake = CpuModel {
34-
extended_family: 0,
35-
extended_model: 5,
36-
family: 6,
37-
model: 5,
38-
stepping: 7,
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};
40-
41-
self >= &cascade_lake
42-
}
4366
}
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4568
impl From<&u32> for CpuModel {
@@ -64,49 +87,14 @@ impl From<&CpuModel> for u32 {
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}
6588
}
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67-
impl PartialOrd for CpuModel {
68-
fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
69-
Some(u32::from(self).cmp(&u32::from(other)))
70-
}
71-
}
72-
73-
impl Ord for CpuModel {
74-
fn cmp(&self, other: &Self) -> Ordering {
75-
u32::from(self).cmp(&u32::from(other))
76-
}
77-
}
78-
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#[cfg(test)]
8091
mod tests {
8192
use super::*;
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83-
const SKYLAKE: CpuModel = CpuModel {
84-
extended_family: 0,
85-
extended_model: 5,
86-
family: 6,
87-
model: 5,
88-
stepping: 4,
89-
};
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91-
const CASCADE_LAKE: CpuModel = CpuModel {
92-
extended_family: 0,
93-
extended_model: 5,
94-
family: 6,
95-
model: 5,
96-
stepping: 7,
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};
98-
9994
#[test]
10095
fn cpu_model_from() {
10196
let skylake_eax = 0x00050654;
102-
assert_eq!(u32::from(&SKYLAKE), skylake_eax);
103-
assert_eq!(CpuModel::from(&skylake_eax), SKYLAKE);
104-
}
105-
106-
#[test]
107-
fn cpu_model_ord() {
108-
assert_eq!(SKYLAKE, SKYLAKE);
109-
assert!(SKYLAKE < CASCADE_LAKE);
110-
assert!(CASCADE_LAKE > SKYLAKE);
97+
assert_eq!(u32::from(&SKYLAKE_FMS), skylake_eax);
98+
assert_eq!(CpuModel::from(&skylake_eax), SKYLAKE_FMS);
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}
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}

‎src/vmm/src/arch/x86_64/vcpu.rs‎

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Original file line numberDiff line numberDiff line change
@@ -797,7 +797,9 @@ mod tests {
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798798
use super::*;
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use crate::arch::BootProtocol;
800-
use crate::arch::x86_64::cpu_model::CpuModel;
800+
use crate::arch::x86_64::cpu_model::{
801+
CASCADE_LAKE_FMS, CpuModel, ICE_LAKE_FMS, MILAN_FMS, SKYLAKE_FMS,
802+
};
801803
use crate::cpu_config::templates::{
802804
CpuConfiguration, CpuTemplateType, CustomCpuTemplate, GetCpuTemplate, GuestConfigError,
803805
StaticCpuTemplate,
@@ -832,17 +834,6 @@ mod tests {
832834
(kvm, vm, vcpu)
833835
}
834836

835-
fn is_at_least_cascade_lake() -> bool {
836-
CpuModel::get_cpu_model()
837-
>= (CpuModel {
838-
extended_family: 0,
839-
extended_model: 5,
840-
family: 6,
841-
model: 5,
842-
stepping: 7,
843-
})
844-
}
845-
846837
fn create_vcpu_config(
847838
kvm: &Kvm,
848839
vcpu: &KvmVcpu,
@@ -915,24 +906,37 @@ mod tests {
915906
// Test configure while using the T2S template.
916907
let t2a_res = try_configure(&kvm, &mut vcpu, StaticCpuTemplate::T2A);
917908

909+
let cpu_model = CpuModel::get_cpu_model();
918910
match &cpuid::common::get_vendor_id_from_host().unwrap() {
919911
cpuid::VENDOR_ID_INTEL => {
920-
assert!(t2_res);
921-
assert!(c3_res);
922-
assert!(t2s_res);
923-
if is_at_least_cascade_lake() {
924-
assert!(t2cl_res);
925-
} else {
926-
assert!(!t2cl_res);
927-
}
912+
assert_eq!(
913+
t2_res,
914+
cpu_model == SKYLAKE_FMS
915+
|| cpu_model == CASCADE_LAKE_FMS
916+
|| cpu_model == ICE_LAKE_FMS
917+
);
918+
assert_eq!(
919+
c3_res,
920+
cpu_model == SKYLAKE_FMS
921+
|| cpu_model == CASCADE_LAKE_FMS
922+
|| cpu_model == ICE_LAKE_FMS
923+
);
924+
assert_eq!(
925+
t2s_res,
926+
cpu_model == SKYLAKE_FMS || cpu_model == CASCADE_LAKE_FMS
927+
);
928+
assert_eq!(
929+
t2cl_res,
930+
cpu_model == CASCADE_LAKE_FMS || cpu_model == ICE_LAKE_FMS
931+
);
928932
assert!(!t2a_res);
929933
}
930934
cpuid::VENDOR_ID_AMD => {
931935
assert!(!t2_res);
932936
assert!(!c3_res);
933937
assert!(!t2s_res);
934938
assert!(!t2cl_res);
935-
assert!(t2a_res);
939+
assert_eq!(t2a_res, cpu_model == MILAN_FMS);
936940
}
937941
_ => {
938942
assert!(!t2_res);

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