diff options
| author | Michael S. Tsirkin <mst@redhat.com> | 2018-06-22 22:22:05 +0300 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2018-06-28 19:05:37 +0200 |
| commit | 6f131f13e68d648a8e4f083c667ab1acd88ce4cd (patch) | |
| tree | 16fd8a1a96b1bb1f4f0cdf82c81607c1a271acad /target/i386 | |
| parent | 0c8465440d50c18a7bb13d0a866748f0593e193a (diff) | |
kvm: support -overcommit cpu-pm=on|off
With this flag, kvm allows guest to control host CPU power state. This
increases latency for other processes using same host CPU in an
unpredictable way, but if decreases idle entry/exit times for the
running VCPU, so to use it QEMU needs a hint about whether host CPU is
overcommitted, hence the flag name.
Follow-up patches will expose this capability to guest
(using mwait leaf).
Based on a patch by Wanpeng Li <kernellwp@gmail.com> .
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Message-Id: <20180622192148.178309-2-mst@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'target/i386')
| -rw-r--r-- | target/i386/kvm.c | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/target/i386/kvm.c b/target/i386/kvm.c index 2d174f3a91..dc991f6aca 100644 --- a/target/i386/kvm.c +++ b/target/i386/kvm.c @@ -1387,6 +1387,29 @@ int kvm_arch_init(MachineState *ms, KVMState *s) smram_machine_done.notify = register_smram_listener; qemu_add_machine_init_done_notifier(&smram_machine_done); } + + if (enable_cpu_pm) { + int disable_exits = kvm_check_extension(s, KVM_CAP_X86_DISABLE_EXITS); + int ret; + +/* Work around for kernel header with a typo. TODO: fix header and drop. */ +#if defined(KVM_X86_DISABLE_EXITS_HTL) && !defined(KVM_X86_DISABLE_EXITS_HLT) +#define KVM_X86_DISABLE_EXITS_HLT KVM_X86_DISABLE_EXITS_HTL +#endif + if (disable_exits) { + disable_exits &= (KVM_X86_DISABLE_EXITS_MWAIT | + KVM_X86_DISABLE_EXITS_HLT | + KVM_X86_DISABLE_EXITS_PAUSE); + } + + ret = kvm_vm_enable_cap(s, KVM_CAP_X86_DISABLE_EXITS, 0, + disable_exits); + if (ret < 0) { + error_report("kvm: guest stopping CPU not supported: %s", + strerror(-ret)); + } + } + return 0; } |