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target-i386: Reorganize TSC rate setting code 

Following changes are made to the TSC rate setting code in
kvm_arch_init_vcpu():
 * The code is moved to a new function kvm_arch_set_tsc_khz().
 * If kvm_arch_set_tsc_khz() fails, i.e. following two conditions are
   both satisfied:
   * KVM does not support the TSC scaling or it fails to set vcpu's
     TSC rate by KVM_SET_TSC_KHZ,
   * the TSC rate to be set is different than the value currently used
     by KVM, then kvm_arch_init_vcpu() will fail. Prevously,
   * the lack of TSC scaling never failed kvm_arch_init_vcpu(),
   * the failure of KVM_SET_TSC_KHZ failed kvm_arch_init_vcpu()
     unconditionally, even though the TSC rate to be set is identical
     to the value currently used by KVM.

Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
This commit is contained in:
Haozhong Zhang 2015-11-24 11:33:56 +08:00 committed by Eduardo Habkost
parent bcffbeeb82
commit 5031283d52
1 changed files with 33 additions and 7 deletions
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40
target-i386/kvm.c
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@ -532,6 +532,36 @@ static bool hyperv_enabled(X86CPU *cpu)
cpu->hyperv_stimer);
}
static int kvm_arch_set_tsc_khz(CPUState *cs)
{
X86CPU *cpu = X86_CPU(cs);
CPUX86State *env = &cpu->env;
int r;
if (!env->tsc_khz) {
return 0;
}
r = kvm_check_extension(cs->kvm_state, KVM_CAP_TSC_CONTROL) ?
kvm_vcpu_ioctl(cs, KVM_SET_TSC_KHZ, env->tsc_khz) :
-ENOTSUP;
if (r < 0) {
/* When KVM_SET_TSC_KHZ fails, it's an error only if the current
* TSC frequency doesn't match the one we want.
*/
int cur_freq = kvm_check_extension(cs->kvm_state, KVM_CAP_GET_TSC_KHZ) ?
kvm_vcpu_ioctl(cs, KVM_GET_TSC_KHZ) :
-ENOTSUP;
if (cur_freq <= 0 || cur_freq != env->tsc_khz) {
error_report("warning: TSC frequency mismatch between "
"VM and host, and TSC scaling unavailable");
return r;
}
}
return 0;
}
static Error *invtsc_mig_blocker;
#define KVM_MAX_CPUID_ENTRIES 100
@ -859,13 +889,9 @@ int kvm_arch_init_vcpu(CPUState *cs)
return r;
}
r = kvm_check_extension(cs->kvm_state, KVM_CAP_TSC_CONTROL);
if (r && env->tsc_khz) {
r = kvm_vcpu_ioctl(cs, KVM_SET_TSC_KHZ, env->tsc_khz);
if (r < 0) {
fprintf(stderr, "KVM_SET_TSC_KHZ failed\n");
return r;
}
r = kvm_arch_set_tsc_khz(cs);
if (r < 0) {
return r;
}
/* vcpu's TSC frequency is either specified by user, or following