Re: [PATCH v7 3/8] s390x/pci: enable for load/store intepretation

[Matthew Rosato <mjrosato@linux.ibm.com>]

On 6/22/22 4:35 AM, Pierre Morel wrote:
> 
> 
> On 6/6/22 22:36, Matthew Rosato wrote:
>> If the ZPCI_OP ioctl reports that is is available and usable, then the
>> underlying KVM host will enable load/store intepretation for any guest
>> device without a SHM bit in the guest function handle.  For a device that
>> will be using interpretation support, ensure the guest function handle
>> matches the host function handle; this value is re-checked every time the
>> guest issues a SET PCI FN to enable the guest device as it is the only
>> opportunity to reflect function handle changes.
>>
>> By default, unless interpret=off is specified, interpretation support 
>> will
>> always be assumed and exploited if the necessary ioctl and features are
>> available on the host kernel.  When these are unavailable, we will 
>> silently
>> revert to the interception model; this allows existing guest 
>> configurations
>> to work unmodified on hosts with and without zPCI interpretation support,
>> allowing QEMU to choose the best support model available.
>>
>> Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
>> ---
>>   hw/s390x/meson.build            |  1 +
>>   hw/s390x/s390-pci-bus.c         | 66 ++++++++++++++++++++++++++++++++-
>>   hw/s390x/s390-pci-inst.c        | 16 ++++++++
>>   hw/s390x/s390-pci-kvm.c         | 22 +++++++++++
>>   include/hw/s390x/s390-pci-bus.h |  1 +
>>   include/hw/s390x/s390-pci-kvm.h | 24 ++++++++++++
>>   target/s390x/kvm/kvm.c          |  7 ++++
>>   target/s390x/kvm/kvm_s390x.h    |  1 +
>>   8 files changed, 137 insertions(+), 1 deletion(-)
>>   create mode 100644 hw/s390x/s390-pci-kvm.c
>>   create mode 100644 include/hw/s390x/s390-pci-kvm.h
>>
>> diff --git a/hw/s390x/meson.build b/hw/s390x/meson.build
>> index feefe0717e..f291016fee 100644
>> --- a/hw/s390x/meson.build
>> +++ b/hw/s390x/meson.build
>> @@ -23,6 +23,7 @@ s390x_ss.add(when: 'CONFIG_KVM', if_true: files(
>>     's390-skeys-kvm.c',
>>     's390-stattrib-kvm.c',
>>     'pv.c',
>> +  's390-pci-kvm.c',
>>   ))
> 
> Here...
> 
>> diff --git a/hw/s390x/s390-pci-kvm.c b/hw/s390x/s390-pci-kvm.c
>> new file mode 100644
>> index 0000000000..0f16104a74
>> --- /dev/null
>> +++ b/hw/s390x/s390-pci-kvm.c
> 
> ...and here:
> 
> Shouldn't this file go in target/s390x/kvm ?
> 
> 

I wasn't sure tbh, there seems to be precedent to use hw/s390x already 
today for kvm-specific pieces of hardware support (e.g. tod, skeys, pv, 
stattrib) whereas target/s390x/kvm has only kvm.c?

Anyone else have an opinion on this one?