[Qemu-devel] [PATCH v2 11/17] kvm: x86: Reset paravirtual MSRs

[Jan Kiszka]

From: Jan Kiszka <address@hidden>

Make sure to clear MSR_KVM_SYSTEM_TIME, MSR_KVM_WALL_CLOCK, and
MSR_KVM_ASYNC_PF_EN so that a freshly booted guest cannot be disturbed
by old values.

Signed-off-by: Jan Kiszka <address@hidden>
CC: Glauber Costa <address@hidden>
---
 target-i386/kvm.c |   10 ++++++++++
 1 files changed, 10 insertions(+), 0 deletions(-)

diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index d8f26bf..664a4a0 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -453,6 +453,9 @@ void kvm_arch_reset_vcpu(CPUState *env)
     env->nmi_injected = 0;
     env->nmi_pending = 0;
     env->xcr0 = 1;
+    env->system_time_msr = 0;
+    env->wall_clock_msr = 0;
+    env->async_pf_en_msr = 0;
     if (kvm_irqchip_in_kernel()) {
         env->mp_state = cpu_is_bsp(env) ? KVM_MP_STATE_RUNNABLE :
                                           KVM_MP_STATE_UNINITIALIZED;
@@ -845,6 +848,13 @@ static int kvm_put_msrs(CPUState *env, int level)
         if (smp_cpus == 1 || env->tsc != 0) {
             kvm_msr_entry_set(&msrs[n++], MSR_IA32_TSC, env->tsc);
         }
+    }
+    /*
+     * The following paravirtual MSRs have side effects on the guest or are
+     * too heavy for normal writeback. Limit them to reset or full state
+     * updates.
+     */
+    if (level >= KVM_PUT_RESET_STATE) {
         kvm_msr_entry_set(&msrs[n++], MSR_KVM_SYSTEM_TIME,
                           env->system_time_msr);
         kvm_msr_entry_set(&msrs[n++], MSR_KVM_WALL_CLOCK, env->wall_clock_msr);
-- 
1.7.1