On Thu, Aug 19, 2010 at 10:07:44PM -1000, Zachary Amsden wrote: > Add an IOCTL for setting the TSC rate for a VM, intended to > be used to migrate non-kvmclock based VMs which rely on TSC > rate staying stable across host migration. > > Signed-off-by: Zachary Amsden <[email protected]> > --- > arch/x86/kvm/x86.c | 36 ++++++++++++++++++++++++++++++++++++ > include/linux/kvm.h | 4 ++++ > 2 files changed, 40 insertions(+), 0 deletions(-) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 887e30f..e618265 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -1017,6 +1017,10 @@ static int kvm_guest_time_update(struct kvm_vcpu *v) > kvm_x86_ops->adjust_tsc_offset(v, tsc-tsc_timestamp); > local_irq_restore(flags); > > + /* hw_tsc_khz unknown at creation time, check for overrun */ > + if (this_tsc_khz > v->kvm->arch.virtual_tsc_khz) > + vcpu->tsc_overrun = 1; > + > /* Now, see if we need to switch into trap mode */ > if (vcpu->tsc_overrun && !vcpu->tsc_trapping) > kvm_x86_ops->set_tsc_trap(v, 1); > @@ -1846,6 +1850,7 @@ int kvm_dev_ioctl_check_extension(long ext) > case KVM_CAP_DEBUGREGS: > case KVM_CAP_X86_ROBUST_SINGLESTEP: > case KVM_CAP_XSAVE: > + case KVM_CAP_SET_TSC_RATE: > r = 1; > break; > case KVM_CAP_COALESCED_MMIO: > @@ -3413,6 +3418,37 @@ long kvm_arch_vm_ioctl(struct file *filp, > r = 0; > break; > } > + case KVM_X86_GET_TSC_RATE: { > + u32 rate = kvm->arch.virtual_tsc_khz; > + r = -EFAULT; > + if (copy_to_user(argp, &rate, sizeof(rate))) > + goto out; > + r = 0; > + break; > + } > + case KVM_X86_SET_TSC_RATE: { > + u32 rate; > + int i; > + struct kvm_vcpu *vcpu; > + r = -EFAULT; > + if (copy_from_user(&rate, argp, sizeof rate)) > + goto out; > + if (rate == 0 || rate > (1ULL << 40)) { > + r = -EINVAL; > + break; > + } > + /* > + * This is intended to be called once, during VM creation. > + * Calling this with running VCPUs to dynamically change > + * speed is risky; there is no synchronization with the > + * compensation loop, so computations using virtual_tsc_khz > + * conversions may go haywire. Use at your own risk. > + */ > + kvm_arch_set_tsc_khz(kvm, rate); > + kvm_for_each_vcpu(i, vcpu, kvm) > + kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu); > + break; > + } > > default: > ; > diff --git a/include/linux/kvm.h b/include/linux/kvm.h > index 3707704..22d27f2 100644 > --- a/include/linux/kvm.h > +++ b/include/linux/kvm.h > @@ -539,6 +539,7 @@ struct kvm_ppc_pvinfo { > #define KVM_CAP_XCRS 56 > #endif > #define KVM_CAP_PPC_GET_PVINFO 57 > +#define KVM_CAP_SET_TSC_RATE 58 > > #ifdef KVM_CAP_IRQ_ROUTING > > @@ -675,6 +676,9 @@ struct kvm_clock_data { > #define KVM_SET_PIT2 _IOW(KVMIO, 0xa0, struct kvm_pit_state2) > /* Available with KVM_CAP_PPC_GET_PVINFO */ > #define KVM_PPC_GET_PVINFO _IOW(KVMIO, 0xa1, struct kvm_ppc_pvinfo) > +/* Available with KVM_CAP_SET_TSC_RATE */ > +#define KVM_X86_GET_TSC_RATE _IOR(KVMIO, 0xa2, __u32) > +#define KVM_X86_SET_TSC_RATE _IOW(KVMIO, 0xa3, __u32)
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