Commit-ID: 0092e4346f49558e5fe5a927c6d78d401dc4ed73 Gitweb: https://git.kernel.org/tip/0092e4346f49558e5fe5a927c6d78d401dc4ed73 Author: Vitaly Kuznetsov <vkuzn...@redhat.com> AuthorDate: Wed, 24 Jan 2018 14:23:37 +0100 Committer: Thomas Gleixner <t...@linutronix.de> CommitDate: Tue, 30 Jan 2018 23:55:34 +0100
x86/kvm: Support Hyper-V reenlightenment When running nested KVM on Hyper-V guests its required to update masterclocks for all guests when L1 migrates to a host with different TSC frequency. Implement the procedure in the following way: - Pause all guests. - Tell the host (Hyper-V) to stop emulating TSC accesses. - Update the gtod copy, recompute clocks. - Unpause all guests. This is somewhat similar to cpufreq but there are two important differences: - TSC emulation can only be disabled globally (on all CPUs) - The new TSC frequency is not known until emulation is turned off so there is no way to 'prepare' for the event upfront. Signed-off-by: Vitaly Kuznetsov <vkuzn...@redhat.com> Signed-off-by: Thomas Gleixner <t...@linutronix.de> Acked-by: Paolo Bonzini <pbonz...@redhat.com> Cc: Stephen Hemminger <sthem...@microsoft.com> Cc: k...@vger.kernel.org Cc: Radim Krčmář <rkrc...@redhat.com> Cc: Haiyang Zhang <haiya...@microsoft.com> Cc: "Michael Kelley (EOSG)" <michael.h.kel...@microsoft.com> Cc: Roman Kagan <rka...@virtuozzo.com> Cc: Andy Lutomirski <l...@kernel.org> Cc: de...@linuxdriverproject.org Cc: "K. Y. Srinivasan" <k...@microsoft.com> Cc: Cathy Avery <cav...@redhat.com> Cc: Mohammed Gamal <mmo...@redhat.com> Link: https://lkml.kernel.org/r/20180124132337.30138-8-vkuzn...@redhat.com --- arch/x86/kvm/x86.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index b1ce368..879a999 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -68,6 +68,7 @@ #include <asm/div64.h> #include <asm/irq_remapping.h> #include <asm/mshyperv.h> +#include <asm/hypervisor.h> #define CREATE_TRACE_POINTS #include "trace.h" @@ -5932,6 +5933,43 @@ static void tsc_khz_changed(void *data) __this_cpu_write(cpu_tsc_khz, khz); } +static void kvm_hyperv_tsc_notifier(void) +{ +#ifdef CONFIG_X86_64 + struct kvm *kvm; + struct kvm_vcpu *vcpu; + int cpu; + + spin_lock(&kvm_lock); + list_for_each_entry(kvm, &vm_list, vm_list) + kvm_make_mclock_inprogress_request(kvm); + + hyperv_stop_tsc_emulation(); + + /* TSC frequency always matches when on Hyper-V */ + for_each_present_cpu(cpu) + per_cpu(cpu_tsc_khz, cpu) = tsc_khz; + kvm_max_guest_tsc_khz = tsc_khz; + + list_for_each_entry(kvm, &vm_list, vm_list) { + struct kvm_arch *ka = &kvm->arch; + + spin_lock(&ka->pvclock_gtod_sync_lock); + + pvclock_update_vm_gtod_copy(kvm); + + kvm_for_each_vcpu(cpu, vcpu, kvm) + kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu); + + kvm_for_each_vcpu(cpu, vcpu, kvm) + kvm_clear_request(KVM_REQ_MCLOCK_INPROGRESS, vcpu); + + spin_unlock(&ka->pvclock_gtod_sync_lock); + } + spin_unlock(&kvm_lock); +#endif +} + static int kvmclock_cpufreq_notifier(struct notifier_block *nb, unsigned long val, void *data) { @@ -6217,6 +6255,9 @@ int kvm_arch_init(void *opaque) kvm_lapic_init(); #ifdef CONFIG_X86_64 pvclock_gtod_register_notifier(&pvclock_gtod_notifier); + + if (x86_hyper_type == X86_HYPER_MS_HYPERV) + set_hv_tscchange_cb(kvm_hyperv_tsc_notifier); #endif return 0; @@ -6229,6 +6270,10 @@ out: void kvm_arch_exit(void) { +#ifdef CONFIG_X86_64 + if (x86_hyper_type == X86_HYPER_MS_HYPERV) + clear_hv_tscchange_cb(); +#endif kvm_lapic_exit(); perf_unregister_guest_info_callbacks(&kvm_guest_cbs);
