x86/kvm: Support Hyper-V reenlightenment (0092e434) · Commits · 戴 / test

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 <vkuznets@redhat.com> Signed-off-by:

Thomas Gleixner <tglx@linutronix.de> Acked-by:

Paolo Bonzini <pbonzini@redhat.com> Cc: Stephen Hemminger <sthemmin@microsoft.com> Cc: kvm@vger.kernel.org Cc: Radim Krčmář <rkrcmar@redhat.com> Cc: Haiyang Zhang <haiyangz@microsoft.com> Cc: "Michael Kelley (EOSG)" <Michael.H.Kelley@microsoft.com> Cc: Roman Kagan <rkagan@virtuozzo.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: devel@linuxdriverproject.org Cc: "K. Y. Srinivasan" <kys@microsoft.com> Cc: Cathy Avery <cavery@redhat.com> Cc: Mohammed Gamal <mmorsy@redhat.com> Link: https://lkml.kernel.org/r/20180124132337.30138-8-vkuznets@redhat.com

arch/x86/kvm/x86.c

+45 −0

Original line number	Diff line number	Diff line
		@@ -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);

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