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From: David Hildenbrand <david@redhat.com>
Message-ID: <12222bae-b5a6-2dc1-f768-a252fdaece63@redhat.com>
Date: Mon, 4 Jun 2018 13:59:32 +0200
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Subject: Re: [Qemu-devel] [PATCH v1 3/7] s390x/tcg: properly implement the
 TOD
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To: Cornelia Huck <cohuck@redhat.com>
Cc: qemu-s390x@nongnu.org, qemu-devel@nongnu.org, Richard Henderson <rth@twiddle.net>, Alexander Graf <agraf@suse.de>, Christian Borntraeger <borntraeger@de.ibm.com>, Thomas Huth <thuth@redhat.com>, "Jason J . Herne" <jjherne@linux.ibm.com>, "Collin L . Walling" <walling@linux.ibm.com>

On 04.06.2018 13:57, Cornelia Huck wrote:
> On Fri, 25 May 2018 13:37:04 +0200
> David Hildenbrand <david@redhat.com> wrote:
> 
>> Right now, each CPU has its own TOD. Especially, the TOD will differ
>> based on creation time of a CPU - e.g. when hotplugging a CPU the times
>> will differ quite a lot, resulting in stall warnings in the guest.
>>
>> Let's use a single TOD by implementing our new TOD device. Prepare it
>> for TOD-clock epoch extension.
>>
>> Most importantly, whenever we set the TOD, we have to update the CKC
>> timer.
>>
>> Signed-off-by: David Hildenbrand <david@redhat.com>
>> ---
>>  hw/s390x/tod-qemu.c        | 45 ++++++++++++++++++++++++++++++++++----
>>  hw/s390x/tod.c             | 11 ++++++++++
>>  include/hw/s390x/tod.h     | 19 ++++++++++++++++
>>  target/s390x/cpu.c         |  8 +------
>>  target/s390x/cpu.h         |  6 ++++-
>>  target/s390x/internal.h    | 15 -------------
>>  target/s390x/misc_helper.c | 32 ++++++++++++++++++++++-----
>>  7 files changed, 103 insertions(+), 33 deletions(-)
> 
>> diff --git a/include/hw/s390x/tod.h b/include/hw/s390x/tod.h
>> index 43ed71600f..5491245b86 100644
>> --- a/include/hw/s390x/tod.h
>> +++ b/include/hw/s390x/tod.h
>> @@ -30,6 +30,9 @@ typedef struct S390TOD {
>>  typedef struct S390TODState {
>>      /* private */
>>      DeviceState parent_obj;
>> +
>> +    /* unused by KVM implementation */
>> +    S390TOD base;
> 
> Does this need some kind of migration handling?

This will be automatically migrated by migrating the TOD value itself now :)

> 
>>  } S390TODState;
>>  
>>  typedef struct S390TODClass {


-- 

Thanks,

David / dhildenb