Commit-ID: 0092e4346f49558e5fe5a927c6d78d401dc4ed73
Gitweb: https://git.kernel.org/tip/0092e4346f49558e5fe5a927c6d78d401dc4ed73
Author: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
AuthorDate: Wed, 24 Jan 2018 14:23:37 +0100
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
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 <vkuznets@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Acked-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: Stephen Hemminger <sthemmin@xxxxxxxxxxxxx>
Cc: kvm@xxxxxxxxxxxxxxx
Cc: Radim Krčmář <rkrcmar@xxxxxxxxxx>
Cc: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
Cc: "Michael Kelley (EOSG)" <Michael.H.Kelley@xxxxxxxxxxxxx>
Cc: Roman Kagan <rkagan@xxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: devel@xxxxxxxxxxxxxxxxxxxxxx
Cc: "K. Y. Srinivasan" <kys@xxxxxxxxxxxxx>
Cc: Cathy Avery <cavery@xxxxxxxxxx>
Cc: Mohammed Gamal <mmorsy@xxxxxxxxxx>
Link: https://lkml.kernel.org/r/20180124132337.30138-8-vkuznets@xxxxxxxxxx
---
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);
--
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