diff options
| author | Rob Landley <rlandley@parallels.com> | 2011-05-06 09:22:02 -0700 |
|---|---|---|
| committer | Randy Dunlap <randy.dunlap@oracle.com> | 2011-05-06 09:22:02 -0700 |
| commit | ed16648eb5b86917f0b90bdcdbc857202da72f90 (patch) | |
| tree | a8198415a6c2f1909f02340b05d36e1d53b82320 /Documentation/virtual/kvm/cpuid.txt | |
| parent | bfd412db9e7b0d8f7b9c09d12d07aa2ac785f1d0 (diff) | |
Move kvm, uml, and lguest subdirectories under a common "virtual" directory, I.E:
cd Documentation
mkdir virtual
git mv kvm uml lguest virtual
Signed-off-by: Rob Landley <rlandley@parallels.com>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Diffstat (limited to 'Documentation/virtual/kvm/cpuid.txt')
| -rw-r--r-- | Documentation/virtual/kvm/cpuid.txt | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/Documentation/virtual/kvm/cpuid.txt b/Documentation/virtual/kvm/cpuid.txt new file mode 100644 index 00000000000..882068538c9 --- /dev/null +++ b/Documentation/virtual/kvm/cpuid.txt @@ -0,0 +1,45 @@ +KVM CPUID bits +Glauber Costa <glommer@redhat.com>, Red Hat Inc, 2010 +===================================================== + +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: + +function: KVM_CPUID_SIGNATURE (0x40000000) +returns : eax = 0, + ebx = 0x4b4d564b, + ecx = 0x564b4d56, + edx = 0x4d. +Note that this value in ebx, ecx and edx corresponds to the string "KVMKVMKVM". +This function queries the presence of KVM cpuid leafs. + + +function: define KVM_CPUID_FEATURES (0x40000001) +returns : ebx, ecx, edx = 0 + eax = and OR'ed group of (1 << flag), where each flags is: + + +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_CLOCKSOURCE_STABLE_BIT || 24 || host will warn if no guest-side + || || per-cpu warps are expected in + || || kvmclock. +------------------------------------------------------------------------------ |