Re: [Qemu-devel] [PATCH v3 2/3] target-i386: calculate vcpu's TSC rate to be migrated

[Christian Borntraeger <borntraeger@de.ibm.com>]

Am 02.11.2015 um 10:40 schrieb James Hogan:
> On Mon, Nov 02, 2015 at 05:26:42PM +0800, Haozhong Zhang wrote:
>> The value of the migrated vcpu's TSC rate is determined as below.
>>  1. If a TSC rate is specified by the cpu option 'tsc-freq', then this
>>     user-specified value will be used.
>>  2. If neither a user-specified TSC rate nor a migrated TSC rate is
>>     present, we will use the TSC rate from KVM (returned by
>>     KVM_GET_TSC_KHZ).
>>  3. Otherwise, we will use the migrated TSC rate.
>>
>> Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com>
>> ---
>>  include/sysemu/kvm.h |  2 ++
>>  kvm-all.c            |  1 +
>>  target-arm/kvm.c     |  5 +++++
>>  target-i386/kvm.c    | 33 +++++++++++++++++++++++++++++++++
>>  target-mips/kvm.c    |  5 +++++
>>  target-ppc/kvm.c     |  5 +++++
>>  target-s390x/kvm.c   |  5 +++++
>>  7 files changed, 56 insertions(+)
>>
>> diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
>> index 461ef65..0ec8b98 100644
>> --- a/include/sysemu/kvm.h
>> +++ b/include/sysemu/kvm.h
>> @@ -328,6 +328,8 @@ int kvm_arch_fixup_msi_route(struct kvm_irq_routing_entry *route,
>>  
>>  int kvm_arch_msi_data_to_gsi(uint32_t data);
>>  
>> +int kvm_arch_setup_tsc_khz(CPUState *cpu);
>> +
>>  int kvm_set_irq(KVMState *s, int irq, int level);
>>  int kvm_irqchip_send_msi(KVMState *s, MSIMessage msg);
>>  
>> diff --git a/kvm-all.c b/kvm-all.c
>> index c442838..1ecaf04 100644
>> --- a/kvm-all.c
>> +++ b/kvm-all.c
>> @@ -1757,6 +1757,7 @@ static void do_kvm_cpu_synchronize_post_init(void *arg)
>>  {
>>      CPUState *cpu = arg;
>>  
>> +    kvm_arch_setup_tsc_khz(cpu);
> 
> Sorry if this is a stupid question, but why aren't you doing this from
> the i386 kvm_arch_put_registers when level == KVM_PUT_FULL_STATE, rather
> than introducing x86 specifics to the generic KVM api?
> 
> Cheers
> James

I agree. We should try to keep this in x86 code.