Re: [Qemu-devel] [PATCH/RFC] s390: Provide a configuration and control device

[Alexander Graf]

On 01.04.2014, at 21:23, Christian Borntraeger <address@hidden> wrote:

> On 01/04/14 16:59, Alexander Graf wrote:
>> On 04/01/2014 04:47 PM, Christian Borntraeger wrote:
>>> We want to configure several things in KVM that go beyond what
>>> ENABLE_CAP (we need payload) or ONE_REG (we need it for the VM
>>> and we need to do more complex actions) can provide. Instead of
>>> adding several s390 specific ioctls, lets provide a configuration
>>> and control device that encapsulates different commands into
>>> groups of the same area (MEMORY, CPU, ..)
>>> 
>>> We also provide an initial nameless base group, with a simple first
>>> user to set the guest name. We need that name in the kernel for
>>> the emulation of STSI (which provides the guest name to the guest)
>>> but we need to implement the emulation in supervisor mode, as it
>>> also provides the underlying levels of hipervisors.
>>> 
>>> Currently we have the following GROUPS and ATTRs pending, which
>>> configure some memory management related function or allow to set
>>> the guest facilities, cpuids etc:
>>> 
>>> #define KVM_DEV_CONFIG_GROUP            0
>>> #define KVM_DEV_CONFIG_NAME             0
>>> 
>>> #define KVM_DEV_CONFIG_GROUP_MEM        1
>>> #define KVM_DEV_CONFIG_MEM_ENABLE_CMMA  0
>>> #define KVM_DEV_CONFIG_MEM_CLR_CMMA     1
>>> #define KVM_DEV_CONFIG_MEM_CLR_PAGES    2
>>> 
>>> #define KVM_DEV_CONFIG_GROUP_CPU        2
>>> #define KVM_DEV_CONFIG_CPU_TYPE         0
>>> #define KVM_DEV_CONFIG_CPU_FAC          1
>>> #define KVM_DEV_CONFIG_CPU_FAC_MASK     2
>>> #define KVM_DEV_CONFIG_CPU_IBC          3
>>> #define KVM_DEV_CONFIG_CPU_IBC_RANGE    4
>> 
>> Why would CPU specific information be set in the VM?
> 
> Might be a misleading name here. This is about CPU id and facility list 
> (mostly CPU features).
> The list of facilities and the cpu id is unique on VM level.

Is this a hardware limitation? I thought s390's virtualization instruction 
doesn't have a notion of a VM, but I could easily be wrong.


Alex