Il 16/07/2013 13:42, Gleb Natapov ha scritto:
> On Sun, Jul 07, 2013 at 11:13:37PM +0800, Arthur Chunqi Li wrote:
>> The recent KVM patch adds IA32_FEATURE_CONTROL support. QEMU needs
>> to clear this MSR when reset vCPU and keep the value of it when
>> migration. This patch add this feature.
>>
> So what happens if we migrate from qemu that does not have this patch
> to qemu that does? Since msr_ia32_feature_control will not be migrated
> it will not be set on the destination so destination will not be able to
> use nested vmx.
Yes, that's the same as with every subsection.
> Since nested vmx is experimental it may be to early for
> us to care about it though, and nested vmx does not work with migration
> anyway.
Exactly. The next time you start KVM, it will set the MSR to 5 again.
Paolo
>> Signed-off-by: Arthur Chunqi Li <yzt...@gmail.com>
>> ---
>> target-i386/cpu.h | 2 ++
>> target-i386/kvm.c | 4 ++++
>> target-i386/machine.c | 22 ++++++++++++++++++++++
>> 3 files changed, 28 insertions(+)
>>
>> diff --git a/target-i386/cpu.h b/target-i386/cpu.h
>> index 62e3547..a418e17 100644
>> --- a/target-i386/cpu.h
>> +++ b/target-i386/cpu.h
>> @@ -301,6 +301,7 @@
>> #define MSR_IA32_APICBASE_BSP (1<<8)
>> #define MSR_IA32_APICBASE_ENABLE (1<<11)
>> #define MSR_IA32_APICBASE_BASE (0xfffff<<12)
>> +#define MSR_IA32_FEATURE_CONTROL 0x0000003a
>> #define MSR_TSC_ADJUST 0x0000003b
>> #define MSR_IA32_TSCDEADLINE 0x6e0
>>
>> @@ -813,6 +814,7 @@ typedef struct CPUX86State {
>>
>> uint64_t mcg_status;
>> uint64_t msr_ia32_misc_enable;
>> + uint64_t msr_ia32_feature_control;
>>
>> /* exception/interrupt handling */
>> int error_code;
>> diff --git a/target-i386/kvm.c b/target-i386/kvm.c
>> index 39f4fbb..3cb2161 100644
>> --- a/target-i386/kvm.c
>> +++ b/target-i386/kvm.c
>> @@ -1122,6 +1122,7 @@ static int kvm_put_msrs(X86CPU *cpu, int level)
>> if (hyperv_vapic_recommended()) {
>> kvm_msr_entry_set(&msrs[n++], HV_X64_MSR_APIC_ASSIST_PAGE, 0);
>> }
>> + kvm_msr_entry_set(&msrs[n++], MSR_IA32_FEATURE_CONTROL,
>> env->msr_ia32_feature_control);
>> }
>> if (env->mcg_cap) {
>> int i;
>> @@ -1346,6 +1347,7 @@ static int kvm_get_msrs(X86CPU *cpu)
>> if (has_msr_misc_enable) {
>> msrs[n++].index = MSR_IA32_MISC_ENABLE;
>> }
>> + msrs[n++].index = MSR_IA32_FEATURE_CONTROL;
>>
>> if (!env->tsc_valid) {
>> msrs[n++].index = MSR_IA32_TSC;
>> @@ -1444,6 +1446,8 @@ static int kvm_get_msrs(X86CPU *cpu)
>> case MSR_IA32_MISC_ENABLE:
>> env->msr_ia32_misc_enable = msrs[i].data;
>> break;
>> + case MSR_IA32_FEATURE_CONTROL:
>> + env->msr_ia32_feature_control = msrs[i].data;
>> default:
>> if (msrs[i].index >= MSR_MC0_CTL &&
>> msrs[i].index < MSR_MC0_CTL + (env->mcg_cap & 0xff) * 4) {
>> diff --git a/target-i386/machine.c b/target-i386/machine.c
>> index 3659db9..94ca914 100644
>> --- a/target-i386/machine.c
>> +++ b/target-i386/machine.c
>> @@ -399,6 +399,14 @@ static bool misc_enable_needed(void *opaque)
>> return env->msr_ia32_misc_enable != MSR_IA32_MISC_ENABLE_DEFAULT;
>> }
>>
>> +static bool feature_control_needed(void *opaque)
>> +{
>> + X86CPU *cpu = opaque;
>> + CPUX86State *env = &cpu->env;
>> +
>> + return env->msr_ia32_feature_control != 0;
>> +}
>> +
>> static const VMStateDescription vmstate_msr_ia32_misc_enable = {
>> .name = "cpu/msr_ia32_misc_enable",
>> .version_id = 1,
>> @@ -410,6 +418,17 @@ static const VMStateDescription
>> vmstate_msr_ia32_misc_enable = {
>> }
>> };
>>
>> +static const VMStateDescription vmstate_msr_ia32_feature_control = {
>> + .name = "cpu/msr_ia32_feature_control",
>> + .version_id = 1,
>> + .minimum_version_id = 1,
>> + .minimum_version_id_old = 1,
>> + .fields = (VMStateField []) {
>> + VMSTATE_UINT64(env.msr_ia32_feature_control, X86CPU),
>> + VMSTATE_END_OF_LIST()
>> + }
>> +};
>> +
>> const VMStateDescription vmstate_x86_cpu = {
>> .name = "cpu",
>> .version_id = 12,
>> @@ -535,6 +554,9 @@ const VMStateDescription vmstate_x86_cpu = {
>> }, {
>> .vmsd = &vmstate_msr_ia32_misc_enable,
>> .needed = misc_enable_needed,
>> + }, {
>> + .vmsd = &vmstate_msr_ia32_feature_control,
>> + .needed = feature_control_needed,
>> } , {
>> /* empty */
>> }
>> --
>> 1.7.9.5
>
> --
> Gleb.
>
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