diff options
| author | Jan Kiszka <jan.kiszka@siemens.com> | 2011-12-21 12:28:29 +0100 |
|---|---|---|
| committer | Avi Kivity <avi@redhat.com> | 2011-12-26 13:27:44 +0200 |
| commit | 4d25a066b69fb749a39d0d4c610689dd765a0b0e (patch) | |
| tree | 34f644f5a0f734a815225cade757088a9862318b /include/linux | |
| parent | 3d27e23b17010c668db311140b17bbbb70c78fb9 (diff) | |
KVM: Don't automatically expose the TSC deadline timer in cpuid
Unlike all of the other cpuid bits, the TSC deadline timer bit is set
unconditionally, regardless of what userspace wants.
This is broken in several ways:
- if userspace doesn't use KVM_CREATE_IRQCHIP, and doesn't emulate the TSC
deadline timer feature, a guest that uses the feature will break
- live migration to older host kernels that don't support the TSC deadline
timer will cause the feature to be pulled from under the guest's feet;
breaking it
- guests that are broken wrt the feature will fail.
Fix by not enabling the feature automatically; instead report it to userspace.
Because the feature depends on KVM_CREATE_IRQCHIP, which we cannot guarantee
will be called, we expose it via a KVM_CAP_TSC_DEADLINE_TIMER and not
KVM_GET_SUPPORTED_CPUID.
Fixes the Illumos guest kernel, which uses the TSC deadline timer feature.
[avi: add the KVM_CAP + documentation]
Reported-by: Alexey Zaytsev <alexey.zaytsev@gmail.com>
Tested-by: Alexey Zaytsev <alexey.zaytsev@gmail.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/kvm.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/kvm.h b/include/linux/kvm.h index c3892fc1d53..68e67e50d02 100644 --- a/include/linux/kvm.h +++ b/include/linux/kvm.h @@ -557,6 +557,7 @@ struct kvm_ppc_pvinfo { #define KVM_CAP_MAX_VCPUS 66 /* returns max vcpus per vm */ #define KVM_CAP_PPC_PAPR 68 #define KVM_CAP_S390_GMAP 71 +#define KVM_CAP_TSC_DEADLINE_TIMER 72 #ifdef KVM_CAP_IRQ_ROUTING |