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KVM: x86: Restrict writeback of VCPU state 

Do not write nmi_pending, sipi_vector, and mpstate unless we at least go
through a reset. And TSC as well as KVM wallclocks should only be
written on full sync, otherwise we risk to drop some time on state
read-modify-write.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This commit is contained in:
Jan Kiszka 2010-03-01 19:10:31 +01:00 committed by Marcelo Tosatti
parent ea375f9ab8
commit ea64305139
1 changed files with 20 additions and 12 deletions
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32
target-i386/kvm.c
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@ -546,7 +546,7 @@ static void kvm_msr_entry_set(struct kvm_msr_entry *entry,
entry->data = value; entry->data = value;
} }
static int kvm_put_msrs(CPUState *env) static int kvm_put_msrs(CPUState *env, int level)
{ {
struct { struct {
struct kvm_msrs info; struct kvm_msrs info;
@ -560,7 +560,6 @@ static int kvm_put_msrs(CPUState *env)
kvm_msr_entry_set(&msrs[n++], MSR_IA32_SYSENTER_EIP, env->sysenter_eip); kvm_msr_entry_set(&msrs[n++], MSR_IA32_SYSENTER_EIP, env->sysenter_eip);
if (kvm_has_msr_star(env)) if (kvm_has_msr_star(env))
kvm_msr_entry_set(&msrs[n++], MSR_STAR, env->star); kvm_msr_entry_set(&msrs[n++], MSR_STAR, env->star);
kvm_msr_entry_set(&msrs[n++], MSR_IA32_TSC, env->tsc);
#ifdef TARGET_X86_64 #ifdef TARGET_X86_64
/* FIXME if lm capable */ /* FIXME if lm capable */
kvm_msr_entry_set(&msrs[n++], MSR_CSTAR, env->cstar); kvm_msr_entry_set(&msrs[n++], MSR_CSTAR, env->cstar);
@ -568,8 +567,12 @@ static int kvm_put_msrs(CPUState *env)
kvm_msr_entry_set(&msrs[n++], MSR_FMASK, env->fmask); kvm_msr_entry_set(&msrs[n++], MSR_FMASK, env->fmask);
kvm_msr_entry_set(&msrs[n++], MSR_LSTAR, env->lstar); kvm_msr_entry_set(&msrs[n++], MSR_LSTAR, env->lstar);
#endif #endif
kvm_msr_entry_set(&msrs[n++], MSR_KVM_SYSTEM_TIME, env->system_time_msr); if (level == KVM_PUT_FULL_STATE) {
kvm_msr_entry_set(&msrs[n++], MSR_KVM_WALL_CLOCK, env->wall_clock_msr); kvm_msr_entry_set(&msrs[n++], MSR_IA32_TSC, env->tsc);
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);
}
msr_data.info.nmsrs = n; msr_data.info.nmsrs = n;
@ -782,7 +785,7 @@ static int kvm_get_mp_state(CPUState *env)
return 0; return 0;
} }
static int kvm_put_vcpu_events(CPUState *env) static int kvm_put_vcpu_events(CPUState *env, int level)
{ {
#ifdef KVM_CAP_VCPU_EVENTS #ifdef KVM_CAP_VCPU_EVENTS
struct kvm_vcpu_events events; struct kvm_vcpu_events events;
@ -806,8 +809,11 @@ static int kvm_put_vcpu_events(CPUState *env)
events.sipi_vector = env->sipi_vector; events.sipi_vector = env->sipi_vector;
events.flags = events.flags = 0;
KVM_VCPUEVENT_VALID_NMI_PENDING | KVM_VCPUEVENT_VALID_SIPI_VECTOR; if (level >= KVM_PUT_RESET_STATE) {
events.flags |=
KVM_VCPUEVENT_VALID_NMI_PENDING | KVM_VCPUEVENT_VALID_SIPI_VECTOR;
}
return kvm_vcpu_ioctl(env, KVM_SET_VCPU_EVENTS, &events); return kvm_vcpu_ioctl(env, KVM_SET_VCPU_EVENTS, &events);
#else #else
@ -899,15 +905,17 @@ int kvm_arch_put_registers(CPUState *env, int level)
if (ret < 0) if (ret < 0)
return ret; return ret;
ret = kvm_put_msrs(env); ret = kvm_put_msrs(env, level);
if (ret < 0) if (ret < 0)
return ret; return ret;
ret = kvm_put_mp_state(env); if (level >= KVM_PUT_RESET_STATE) {
if (ret < 0) ret = kvm_put_mp_state(env);
return ret; if (ret < 0)
return ret;
}
ret = kvm_put_vcpu_events(env); ret = kvm_put_vcpu_events(env, level);
if (ret < 0) if (ret < 0)
return ret; return ret;