KVM: s390: add cpu model support

This patch enables cpu model support in kvm/s390 via the vm attribute
interface.

During KVM initialization, the host properties cpuid, IBC value and the
facility list are stored in the architecture specific cpu model structure.

During vcpu setup, these properties are taken to initialize the related SIE
state. This mechanism allows to adjust the properties from user space and thus
to implement different selectable cpu models.

This patch uses the IBC functionality to block instructions that have not
been implemented at the requested CPU type and GA level compared to the
full host capability.

Userspace has to initialize the cpu model before vcpu creation. A cpu model
change of running vcpus is not possible.

Signed-off-by: Michael Mueller <[email protected]>
Reviewed-by: Cornelia Huck <[email protected]>
Reviewed-by: David Hildenbrand <[email protected]>
Signed-off-by: Christian Borntraeger <[email protected]>
This commit is contained in:
Michael Mueller 2015-02-02 15:49:35 +01:00 • committed by Christian Borntraeger
commit 658b6eda20
4 changed files with 201 additions and 1 deletions

View file

@ -38,3 +38,48 @@ Allows userspace to query the actual limit and set a new limit for
the maximum guest memory size. The limit will be rounded up to
2048 MB, 4096 GB, 8192 TB respectively, as this limit is governed by
the number of page table levels.
2. GROUP: KVM_S390_VM_CPU_MODEL
Architectures: s390
2.1. ATTRIBUTE: KVM_S390_VM_CPU_MACHINE (r/o)
Allows user space to retrieve machine and kvm specific cpu related information:
struct kvm_s390_vm_cpu_machine {
__u64 cpuid; # CPUID of host
__u32 ibc; # IBC level range offered by host
__u8 pad[4];
__u64 fac_mask[256]; # set of cpu facilities enabled by KVM
__u64 fac_list[256]; # set of cpu facilities offered by host
}
Parameters: address of buffer to store the machine related cpu data
of type struct kvm_s390_vm_cpu_machine*
Returns: -EFAULT if the given address is not accessible from kernel space
-ENOMEM if not enough memory is available to process the ioctl
0 in case of success
2.2. ATTRIBUTE: KVM_S390_VM_CPU_PROCESSOR (r/w)
Allows user space to retrieve or request to change cpu related information for a vcpu:
struct kvm_s390_vm_cpu_processor {
__u64 cpuid; # CPUID currently (to be) used by this vcpu
__u16 ibc; # IBC level currently (to be) used by this vcpu
__u8 pad[6];
__u64 fac_list[256]; # set of cpu facilities currently (to be) used
# by this vcpu
}
KVM does not enforce or limit the cpu model data in any form. Take the information
retrieved by means of KVM_S390_VM_CPU_MACHINE as hint for reasonable configuration
setups. Instruction interceptions triggered by additionally set facilitiy bits that
are not handled by KVM need to by imlemented in the VM driver code.
Parameters: address of buffer to store/set the processor related cpu
data of type struct kvm_s390_vm_cpu_processor*.
Returns: -EBUSY in case 1 or more vcpus are already activated (only in write case)
-EFAULT if the given address is not accessible from kernel space
-ENOMEM if not enough memory is available to process the ioctl
0 in case of success