From: David Woodhouse <[email protected]>
Previously, the master clock was only activated when the first vCPU
processed KVM_REQ_MASTERCLOCK_UPDATE during KVM_RUN. This meant that
KVM_GET_CLOCK could not return the host_tsc field until after the
first KVM_RUN, making it impossible for userspace to follow the
documented TSC migration procedure without a dummy vCPU run.
Fix this by calling kvm_update_masterclock() directly from
kvm_arch_vcpu_postcreate(), after kvm_synchronize_tsc() has already
set all_vcpus_matched_freq. This ensures the master clock is active
immediately, and KVM_GET_CLOCK returns a valid {host_tsc, realtime}
pair as soon as a vCPU exists.
Signed-off-by: David Woodhouse <[email protected]>
---
arch/x86/kvm/x86.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index b7e5f6e3dc6c..c1897d939da9 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -13098,6 +13098,8 @@ void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu)
return;
vcpu_load(vcpu);
kvm_synchronize_tsc(vcpu, NULL);
+ if (!vcpu->kvm->arch.use_master_clock)
+ kvm_update_masterclock(vcpu->kvm);
vcpu_put(vcpu);
/* poll control enabled by default */
--
2.54.0
