요약·해설과 원문, 전문 번역을 서로 분리했습니다. API 이름, symbol, source path는 원문 표기를 사용합니다.
1. 요약·해설
원문의 핵심 논리와 kernel programming 관점의 보충 설명입니다. 아래의 전문 번역과는 별도로 작성했습니다.
2. 영어 원문 전체
번역 기준이 된 Linux v6.18.37 원문입니다. 줄 번호는 이 버전의 파일 좌표입니다.
원문 전체 펼치기
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.. SPDX-License-Identifier: GPL-2.0
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==============
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KVM CPUID bits
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==============
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:Author: Glauber Costa <glommer@gmail.com>
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A guest running on a kvm host, can check some of its features using
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cpuid. This is not always guaranteed to work, since userspace can
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mask-out some, or even all KVM-related cpuid features before launching
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a guest.
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KVM cpuid functions are:
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function: KVM_CPUID_SIGNATURE (0x40000000)
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returns::
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eax = 0x40000001
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ebx = 0x4b4d564b
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ecx = 0x564b4d56
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edx = 0x4d
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Note that this value in ebx, ecx and edx corresponds to the string "KVMKVMKVM".
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The value in eax corresponds to the maximum cpuid function present in this leaf,
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and will be updated if more functions are added in the future.
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Note also that old hosts set eax value to 0x0. This should
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be interpreted as if the value was 0x40000001.
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This function queries the presence of KVM cpuid leafs.
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function: define KVM_CPUID_FEATURES (0x40000001)
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returns::
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ebx, ecx
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eax = an OR'ed group of (1 << flag)
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where ``flag`` is defined as below:
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================================== =========== ================================
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flag value meaning
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================================== =========== ================================
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KVM_FEATURE_CLOCKSOURCE 0 kvmclock available at msrs
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0x11 and 0x12
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KVM_FEATURE_NOP_IO_DELAY 1 not necessary to perform delays
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on PIO operations
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KVM_FEATURE_MMU_OP 2 deprecated
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KVM_FEATURE_CLOCKSOURCE2 3 kvmclock available at msrs
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0x4b564d00 and 0x4b564d01
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KVM_FEATURE_ASYNC_PF 4 async pf can be enabled by
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writing to msr 0x4b564d02
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KVM_FEATURE_STEAL_TIME 5 steal time can be enabled by
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writing to msr 0x4b564d03
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KVM_FEATURE_PV_EOI 6 paravirtualized end of interrupt
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handler can be enabled by
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writing to msr 0x4b564d04
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KVM_FEATURE_PV_UNHALT 7 guest checks this feature bit
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before enabling paravirtualized
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spinlock support
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KVM_FEATURE_PV_TLB_FLUSH 9 guest checks this feature bit
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before enabling paravirtualized
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tlb flush
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KVM_FEATURE_ASYNC_PF_VMEXIT 10 paravirtualized async PF VM EXIT
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can be enabled by setting bit 2
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when writing to msr 0x4b564d02
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KVM_FEATURE_PV_SEND_IPI 11 guest checks this feature bit
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before enabling paravirtualized
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send IPIs
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KVM_FEATURE_POLL_CONTROL 12 host-side polling on HLT can
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be disabled by writing
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to msr 0x4b564d05.
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KVM_FEATURE_PV_SCHED_YIELD 13 guest checks this feature bit
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before using paravirtualized
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sched yield.
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KVM_FEATURE_ASYNC_PF_INT 14 guest checks this feature bit
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before using the second async
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pf control msr 0x4b564d06 and
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async pf acknowledgment msr
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0x4b564d07.
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KVM_FEATURE_MSI_EXT_DEST_ID 15 guest checks this feature bit
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before using extended destination
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ID bits in MSI address bits 11-5.
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KVM_FEATURE_HC_MAP_GPA_RANGE 16 guest checks this feature bit before
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using the map gpa range hypercall
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to notify the page state change
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KVM_FEATURE_MIGRATION_CONTROL 17 guest checks this feature bit before
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using MSR_KVM_MIGRATION_CONTROL
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KVM_FEATURE_CLOCKSOURCE_STABLE_BIT 24 host will warn if no guest-side
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per-cpu warps are expected in
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kvmclock
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================================== =========== ================================
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::
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edx = an OR'ed group of (1 << flag)
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Where ``flag`` here is defined as below:
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================== ============ =================================
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flag value meaning
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================== ============ =================================
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KVM_HINTS_REALTIME 0 guest checks this feature bit to
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determine that vCPUs are never
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preempted for an unlimited time
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allowing optimizations
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================== ============ =================================
3. 한국어 전문 번역
영어 원문의 문단 순서와 의미를 유지한 전체 번역입니다. 코드, 함수명, symbol과 URL은 원문 표기를 유지합니다.
게스트의 KVM 기능 탐지
1-15KVM host에서 실행하는 guest는 CPUID로 일부 KVM 기능을 확인할 수 있습니다. 그러나 userspace가 guest 실행 전에 일부 또는 모든 KVM CPUID feature를 mask할 수 있으므로 host 지원이 항상 guest 노출로 이어지지는 않습니다.
.. SPDX-License-Identifier: GPL-2.0
==============
KVM CPUID bits
==============
:Author: Glauber Costa <glommer@gmail.com>
A guest running on a kvm host, can check some of its features using
cpuid. This is not always guaranteed to work, since userspace can
mask-out some, or even all KVM-related cpuid features before launching
a guest.
KVM cpuid functions are:
KVM_CPUID_SIGNATURE
16-31`KVM_CPUID_SIGNATURE (0x40000000)` leaf는 KVM CPUID leaf 존재와 signature를 보고합니다.
Register값과 의미
`EAX``0x40000001`, 현재 최대 KVM CPUID function
`EBX``0x4b4d564b`
`ECX``0x564b4d56`
`EDX``0x4d`; EBX·ECX·EDX를 합치면 `KVMKVMKVM`
반환 register 값입니다.
미래 leaf가 추가되면 EAX 최대값도 갱신됩니다. 오래된 host의 EAX=0은 `0x40000001`로 해석해야 합니다.
function: KVM_CPUID_SIGNATURE (0x40000000)
returns::
eax = 0x40000001
ebx = 0x4b4d564b
ecx = 0x564b4d56
edx = 0x4d
Note that this value in ebx, ecx and edx corresponds to the string "KVMKVMKVM".
The value in eax corresponds to the maximum cpuid function present in this leaf,
and will be updated if more functions are added in the future.
Note also that old hosts set eax value to 0x0. This should
be interpreted as if the value was 0x40000001.
This function queries the presence of KVM cpuid leafs.
KVM_CPUID_FEATURES
32-124`KVM_CPUID_FEATURES (0x40000001)`의 EAX는 `(1 << flag)`를 OR한 feature bitmap이고 EBX·ECX는 이 문서에서 별도 의미를 정의하지 않습니다.
BitFeature의미
0`KVM_FEATURE_CLOCKSOURCE`MSR 0x11·0x12의 kvmclock
1`KVM_FEATURE_NOP_IO_DELAY`PIO delay 불필요
2`KVM_FEATURE_MMU_OP`deprecated
3`KVM_FEATURE_CLOCKSOURCE2`MSR 0x4b564d00·01의 kvmclock
4`KVM_FEATURE_ASYNC_PF`MSR 0x4b564d02로 async PF 활성화
5`KVM_FEATURE_STEAL_TIME`MSR 0x4b564d03으로 steal time 활성화
6`KVM_FEATURE_PV_EOI`MSR 0x4b564d04의 PV EOI
7`KVM_FEATURE_PV_UNHALT`PV spinlock 지원
9`KVM_FEATURE_PV_TLB_FLUSH`PV TLB flush
10`KVM_FEATURE_ASYNC_PF_VMEXIT`MSR 0x4b564d02 bit 2의 async PF VM exit
11`KVM_FEATURE_PV_SEND_IPI`PV IPI 송신
12`KVM_FEATURE_POLL_CONTROL`MSR 0x4b564d05로 host HLT polling 비활성화
13`KVM_FEATURE_PV_SCHED_YIELD`PV scheduler yield
14`KVM_FEATURE_ASYNC_PF_INT`MSR 0x4b564d06·07의 async PF interrupt와 ack
15`KVM_FEATURE_MSI_EXT_DEST_ID`MSI address bit 11-5의 extended destination ID
16`KVM_FEATURE_HC_MAP_GPA_RANGE`GPA page state 변경 하이퍼콜
17`KVM_FEATURE_MIGRATION_CONTROL``MSR_KVM_MIGRATION_CONTROL` 사용
24`KVM_FEATURE_CLOCKSOURCE_STABLE_BIT`guest별 kvmclock warp가 예상되지 않음을 host가 보장
guest가 MSR 또는 하이퍼콜 기능 사용 전에 확인하는 비트입니다.
EDX는 별도 hint bitmap입니다. 현재 bit 0의 `KVM_HINTS_REALTIME`은 vCPU가 무제한 시간 선점되지 않음을 guest에 알려 관련 최적화를 허용합니다.
function: define KVM_CPUID_FEATURES (0x40000001)
returns::
ebx, ecx
eax = an OR'ed group of (1 << flag)
where ``flag`` is defined as below:
================================== =========== ================================
flag value meaning
================================== =========== ================================
KVM_FEATURE_CLOCKSOURCE 0 kvmclock available at msrs
0x11 and 0x12
KVM_FEATURE_NOP_IO_DELAY 1 not necessary to perform delays
on PIO operations
KVM_FEATURE_MMU_OP 2 deprecated
KVM_FEATURE_CLOCKSOURCE2 3 kvmclock available at msrs
0x4b564d00 and 0x4b564d01
KVM_FEATURE_ASYNC_PF 4 async pf can be enabled by
writing to msr 0x4b564d02
KVM_FEATURE_STEAL_TIME 5 steal time can be enabled by
writing to msr 0x4b564d03
KVM_FEATURE_PV_EOI 6 paravirtualized end of interrupt
handler can be enabled by
writing to msr 0x4b564d04
KVM_FEATURE_PV_UNHALT 7 guest checks this feature bit
before enabling paravirtualized
spinlock support
KVM_FEATURE_PV_TLB_FLUSH 9 guest checks this feature bit
before enabling paravirtualized
tlb flush
KVM_FEATURE_ASYNC_PF_VMEXIT 10 paravirtualized async PF VM EXIT
can be enabled by setting bit 2
when writing to msr 0x4b564d02
KVM_FEATURE_PV_SEND_IPI 11 guest checks this feature bit
before enabling paravirtualized
send IPIs
KVM_FEATURE_POLL_CONTROL 12 host-side polling on HLT can
be disabled by writing
to msr 0x4b564d05.
KVM_FEATURE_PV_SCHED_YIELD 13 guest checks this feature bit
before using paravirtualized
sched yield.
KVM_FEATURE_ASYNC_PF_INT 14 guest checks this feature bit
before using the second async
pf control msr 0x4b564d06 and
async pf acknowledgment msr
0x4b564d07.
KVM_FEATURE_MSI_EXT_DEST_ID 15 guest checks this feature bit
before using extended destination
ID bits in MSI address bits 11-5.
KVM_FEATURE_HC_MAP_GPA_RANGE 16 guest checks this feature bit before
using the map gpa range hypercall
to notify the page state change
KVM_FEATURE_MIGRATION_CONTROL 17 guest checks this feature bit before
using MSR_KVM_MIGRATION_CONTROL
KVM_FEATURE_CLOCKSOURCE_STABLE_BIT 24 host will warn if no guest-side
per-cpu warps are expected in
kvmclock
================================== =========== ================================
::
edx = an OR'ed group of (1 << flag)
Where ``flag`` here is defined as below:
================== ============ =================================
flag value meaning
================== ============ =================================
KVM_HINTS_REALTIME 0 guest checks this feature bit to
determine that vCPUs are never
preempted for an unlimited time
allowing optimizations
================== ============ =================================
요약·해설
cpuid.rst:1-124KVM signature와 EAX feature bitmap, EDX realtime hint를 정의합니다.
레지스터, 비트 필드, 구조체와 호출 순서를 원문 표기 및 줄 좌표와 함께 보존했습니다.