KVM: x86: release kvmclock page on reset

When a vcpu is reset, kvmclock page keeps being written to this days.
This is wrong and inconsistent: a cpu reset should take it to its
initial state.

Signed-off-by: Glauber Costa <glommer@redhat.com>
CC: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

1 files changed, 12 insertions, 8 deletions

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 7faf262ab202..712af904706f 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1453,6 +1453,14 @@ static int kvm_pv_enable_async_pf(struct kvm_vcpu *vcpu, u64 data)
         return 0;
 }
 
+static void kvmclock_reset(struct kvm_vcpu *vcpu)
+{
+        if (vcpu->arch.time_page) {
+                kvm_release_page_dirty(vcpu->arch.time_page);
+                vcpu->arch.time_page = NULL;
+        }
+}
+
 int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
 {
         switch (msr) {
@@ -1510,10 +1518,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
                 break;
         case MSR_KVM_SYSTEM_TIME_NEW:
         case MSR_KVM_SYSTEM_TIME: {
-                if (vcpu->arch.time_page) {
-                        kvm_release_page_dirty(vcpu->arch.time_page);
-                        vcpu->arch.time_page = NULL;
-                }
+                kvmclock_reset(vcpu);
 
                 vcpu->arch.time = data;
                 kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu);
@@ -5837,10 +5842,7 @@ void kvm_put_guest_fpu(struct kvm_vcpu *vcpu)
 
 void kvm_arch_vcpu_free(struct kvm_vcpu *vcpu)
 {
-        if (vcpu->arch.time_page) {
-                kvm_release_page_dirty(vcpu->arch.time_page);
-                vcpu->arch.time_page = NULL;
-        }
+        kvmclock_reset(vcpu);
 
         free_cpumask_var(vcpu->arch.wbinvd_dirty_mask);
         fx_free(vcpu);
@@ -5901,6 +5903,8 @@ int kvm_arch_vcpu_reset(struct kvm_vcpu *vcpu)
         kvm_make_request(KVM_REQ_EVENT, vcpu);
         vcpu->arch.apf.msr_val = 0;
 
+        kvmclock_reset(vcpu);
+
         kvm_clear_async_pf_completion_queue(vcpu);
         kvm_async_pf_hash_reset(vcpu);
         vcpu->arch.apf.halted = false;