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authorVitaly Kuznetsov <vkuznets@redhat.com>2018-01-24 14:23:37 +0100
committerThomas Gleixner <tglx@linutronix.de>2018-01-30 23:55:34 +0100
commit0092e4346f49558e5fe5a927c6d78d401dc4ed73 (patch)
treec79a7cd0c76a402eda8883a26d7384175e82703c /arch
parentx86/kvm: Pass stable clocksource to guests when running nested on Hyper-V (diff)
downloadlinux-0092e4346f49558e5fe5a927c6d78d401dc4ed73.tar.xz
linux-0092e4346f49558e5fe5a927c6d78d401dc4ed73.zip
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 <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
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kvm/x86.c45
1 files changed, 45 insertions, 0 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index b1ce368a07af..879a99987401 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);