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feat: AMD support larger extended function entries #4995

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feat: AMD support larger extended function entries #4995

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20 changes: 10 additions & 10 deletions docs/cpu_templates/cpuid-normalization.md
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Original file line number Diff line number Diff line change
Expand Up @@ -42,13 +42,13 @@ See also: [boot protocol settings](boot-protocol.md)

## AMD-specifc CPUID normalization

| Description | Leaf | Subleaf | Register | Bits |
| ---------------------------------------------------- | :--------------------------------: | :-----: | :----------------: | :---: |
| Set IA32_ARCH_CAPABILITIES MSR as not present | 0x7 | - | EDX | 29 |
| Update largest extended function entry to 0x8000001f | 0x80000000 | - | EAX | 31:0 |
| Set topology extension bit | 0x80000001 | - | ECX | 22 |
| Update brand string with a default AMD value | 0x80000002, 0x80000003, 0x80000004 | - | EAX, EBX, ECX, EDX | all |
| Update number of physical threads | 0x80000008 | - | ECX | 7:0 |
| Update APIC ID size | 0x80000008 | - | ECX | 15:12 |
| Update cache topology information | 0x8000001d | all | all | all |
| Update extended APIC ID | 0x8000001e | - | EAX, EBX, ECX | all |
| Description | Leaf | Subleaf | Register | Bits |
| --------------------------------------------------------------------------------------- | :--------------------------------: | :-----: | :----------------: | :---: |
| Set IA32_ARCH_CAPABILITIES MSR as not present | 0x7 | - | EDX | 29 |
| Update largest extended function entry to largest between host cpu entry and 0x80000021 | 0x80000000 | - | EAX | 31:0 |
| Set topology extension bit | 0x80000001 | - | ECX | 22 |
| Update brand string with a default AMD value | 0x80000002, 0x80000003, 0x80000004 | - | EAX, EBX, ECX, EDX | all |
| Update number of physical threads | 0x80000008 | - | ECX | 7:0 |
| Update APIC ID size | 0x80000008 | - | ECX | 15:12 |
| Update cache topology information | 0x8000001d | all | all | all |
| Update extended APIC ID | 0x8000001e | - | EAX, EBX, ECX | all |
12 changes: 9 additions & 3 deletions src/vmm/src/cpu_config/x86_64/cpuid/amd/normalize.rs
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Expand Up @@ -184,17 +184,23 @@ impl super::AmdCpuid {
/// Update largest extended fn entry.
#[allow(clippy::unwrap_used, clippy::unwrap_in_result)]
fn update_largest_extended_fn_entry(&mut self) -> Result<(), NormalizeCpuidError> {
// KVM sets the largest extended function to 0x80000000. Change it to 0x8000001f
// Since we also use the leaf 0x8000001d (Extended Cache Topology).
// KVM sets the largest extended function to 0x80000000. Change it to the largest
// between host CPU and 0x8000_0021. AMD notes that hypervisors should synthesize the value
// of both IBPB_BRTYPE and SBPB stored in leaf 0x8000_0021.
//
// https://www.amd.com/content/dam/amd/en/documents/corporate/cr/speculative-return-stack-overflow-whitepaper.pdf
let leaf_80000000 = self
.get_mut(&CpuidKey::leaf(0x80000000))
.ok_or(NormalizeCpuidError::MissingLeaf0x80000000)?;

// Take the largest between host cpu entry and 0x8000_0021
let extended_fn_entry = 0x8000_0021.max(get_range(cpuid(0x80000000).eax, 0..32));

// Largest extended function. The largest CPUID extended function input value supported by
// the processor implementation.
//
// l_func_ext: 0..32,
set_range(&mut leaf_80000000.result.eax, 0..32, 0x8000_001f).unwrap();
set_range(&mut leaf_80000000.result.eax, 0..32, extended_fn_entry).unwrap();
Ok(())
}

Expand Down
4 changes: 2 additions & 2 deletions tests/data/cpu_template_helper/fingerprint_AMD_MILAN_5.10host.json
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Expand Up @@ -543,7 +543,7 @@
"modifiers": [
{
"register": "eax",
"bitmap": "0b10000000000000000000000000011111"
"bitmap": "0b10000000000000000000000000100011"
},
{
"register": "ebx",
Expand Down Expand Up @@ -1496,4 +1496,4 @@
}
]
}
}
}
4 changes: 2 additions & 2 deletions tests/data/cpu_template_helper/fingerprint_AMD_MILAN_6.1host.json
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Expand Up @@ -543,7 +543,7 @@
"modifiers": [
{
"register": "eax",
"bitmap": "0b10000000000000000000000000011111"
"bitmap": "0b10000000000000000000000000100011"
},
{
"register": "ebx",
Expand Down Expand Up @@ -1546,4 +1546,4 @@
}
]
}
}
}
5 changes: 4 additions & 1 deletion tests/integration_tests/functional/test_cpu_template_helper.py
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Expand Up @@ -146,13 +146,14 @@ def build_cpu_config_dict(cpu_config_path):
# https://github.com/torvalds/linux/commit/8765d75329a386dd7742f94a1ea5fdcdea8d93d0
(0x8000001B, 0x0),
(0x8000001C, 0x0),
(0x8000001F, 0x0),
# CPUID.80860000h is a Transmeta-specific leaf.
(0x80860000, 0x0),
# CPUID.C0000000h is a Centaur-specific leaf.
(0xC0000000, 0x0),
]

# An upper range of CPUID leaves which are not supported by our kernels
UNAVAILABLE_CPUID_UPPER_RANGE = range(0x8000001F, 0x80000029)

# Dictionary of CPUID bitmasks that should not be tested due to its mutability.
CPUID_EXCEPTION_LIST = {
Expand Down Expand Up @@ -281,6 +282,8 @@ def test_cpu_config_dump_vs_actual(
for key, actual in actual_cpu_config["cpuid"].items():
if (key[0], key[1]) in UNAVAILABLE_CPUID_ON_DUMP_LIST:
continue
if key[0] in UNAVAILABLE_CPUID_UPPER_RANGE:
continue
if key not in dump_cpu_config["cpuid"]:
keys_not_in_dump[key] = actual_cpu_config["cpuid"][key]
continue
Expand Down
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