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) /* * ioctls for vcpu fds -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
