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KVM: s390: resetting the Topology-Change-Report

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During a subsystem reset the Topology-Change-Report is cleared.

Let's give userland the possibility to clear the MTCR in the case
of a subsystem reset.

To migrate the MTCR, we give userland the possibility to
query the MTCR state.

We indicate KVM support for the CPU topology facility with a new
KVM capability: KVM_CAP_S390_CPU_TOPOLOGY.

Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
Reviewed-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Message-Id: <20220714194334.127812-1-pmorel@linux.ibm.com>
Link: https://lore.kernel.org/all/20220714194334.127812-1-pmorel@linux.ibm.com/
[frankja@linux.ibm.com: Simple conflict resolution in Documentation/virt/kvm/api.rst]
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
This commit is contained in:
Pierre Morel 2022-07-14 21:43:34 +02:00 committed by Janosch Frank
parent 24fe0195bc
commit f5ecfee944
4 changed files with 78 additions and 0 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

25
Documentation/virt/kvm/api.rst
View file

@ -8269,6 +8269,31 @@ The capability has no effect if the nx_huge_pages module parameter is not set.
This capability may only be set before any vCPUs are created.
8.39 KVM_CAP_S390_CPU_TOPOLOGY
------------------------------
:Capability: KVM_CAP_S390_CPU_TOPOLOGY
:Architectures: s390
:Type: vm
This capability indicates that KVM will provide the S390 CPU Topology
facility which consist of the interpretation of the PTF instruction for
the function code 2 along with interception and forwarding of both the
PTF instruction with function codes 0 or 1 and the STSI(15,1,x)
instruction to the userland hypervisor.
The stfle facility 11, CPU Topology facility, should not be indicated
to the guest without this capability.
When this capability is present, KVM provides a new attribute group
on vm fd, KVM_S390_VM_CPU_TOPOLOGY.
This new attribute allows to get, set or clear the Modified Change
Topology Report (MTCR) bit of the SCA through the kvm_device_attr
structure.
When getting the Modified Change Topology Report value, the attr->addr
must point to a byte where the value will be stored or retrieved from.
9. Known KVM API problems
=========================

1
arch/s390/include/uapi/asm/kvm.h
View file

@ -74,6 +74,7 @@ struct kvm_s390_io_adapter_req {
#define KVM_S390_VM_CRYPTO 2
#define KVM_S390_VM_CPU_MODEL 3
#define KVM_S390_VM_MIGRATION 4
#define KVM_S390_VM_CPU_TOPOLOGY 5
/* kvm attributes for mem_ctrl */
#define KVM_S390_VM_MEM_ENABLE_CMMA 0

51
arch/s390/kvm/kvm-s390.c
View file

@ -642,6 +642,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
case KVM_CAP_S390_ZPCI_OP:
r = kvm_s390_pci_interp_allowed();
break;
case KVM_CAP_S390_CPU_TOPOLOGY:
r = test_facility(11);
break;
default:
r = 0;
}
@ -853,6 +856,20 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap)
icpt_operexc_on_all_vcpus(kvm);
r = 0;
break;
case KVM_CAP_S390_CPU_TOPOLOGY:
r = -EINVAL;
mutex_lock(&kvm->lock);
if (kvm->created_vcpus) {
r = -EBUSY;
} else if (test_facility(11)) {
set_kvm_facility(kvm->arch.model.fac_mask, 11);
set_kvm_facility(kvm->arch.model.fac_list, 11);
r = 0;
}
mutex_unlock(&kvm->lock);
VM_EVENT(kvm, 3, "ENABLE: CAP_S390_CPU_TOPOLOGY %s",
r ? "(not available)" : "(success)");
break;
default:
r = -EINVAL;
break;
@ -1789,6 +1806,31 @@ static void kvm_s390_update_topology_change_report(struct kvm *kvm, bool val)
read_unlock(&kvm->arch.sca_lock);
}
static int kvm_s390_set_topo_change_indication(struct kvm *kvm,
struct kvm_device_attr *attr)
{
if (!test_kvm_facility(kvm, 11))
return -ENXIO;
kvm_s390_update_topology_change_report(kvm, !!attr->attr);
return 0;
}
static int kvm_s390_get_topo_change_indication(struct kvm *kvm,
struct kvm_device_attr *attr)
{
u8 topo;
if (!test_kvm_facility(kvm, 11))
return -ENXIO;
read_lock(&kvm->arch.sca_lock);
topo = ((struct bsca_block *)kvm->arch.sca)->utility.mtcr;
read_unlock(&kvm->arch.sca_lock);
return put_user(topo, (u8 __user *)attr->addr);
}
static int kvm_s390_vm_set_attr(struct kvm *kvm, struct kvm_device_attr *attr)
{
int ret;
@ -1809,6 +1851,9 @@ static int kvm_s390_vm_set_attr(struct kvm *kvm, struct kvm_device_attr *attr)
case KVM_S390_VM_MIGRATION:
ret = kvm_s390_vm_set_migration(kvm, attr);
break;
case KVM_S390_VM_CPU_TOPOLOGY:
ret = kvm_s390_set_topo_change_indication(kvm, attr);
break;
default:
ret = -ENXIO;
break;
@ -1834,6 +1879,9 @@ static int kvm_s390_vm_get_attr(struct kvm *kvm, struct kvm_device_attr *attr)
case KVM_S390_VM_MIGRATION:
ret = kvm_s390_vm_get_migration(kvm, attr);
break;
case KVM_S390_VM_CPU_TOPOLOGY:
ret = kvm_s390_get_topo_change_indication(kvm, attr);
break;
default:
ret = -ENXIO;
break;
@ -1907,6 +1955,9 @@ static int kvm_s390_vm_has_attr(struct kvm *kvm, struct kvm_device_attr *attr)
case KVM_S390_VM_MIGRATION:
ret = 0;
break;
case KVM_S390_VM_CPU_TOPOLOGY:
ret = test_kvm_facility(kvm, 11) ? 0 : -ENXIO;
break;
default:
ret = -ENXIO;
break;

1
include/uapi/linux/kvm.h
View file

@ -1168,6 +1168,7 @@ struct kvm_ppc_resize_hpt {
#define KVM_CAP_X86_NOTIFY_VMEXIT 219
#define KVM_CAP_VM_DISABLE_NX_HUGE_PAGES 220
#define KVM_CAP_S390_ZPCI_OP 221
#define KVM_CAP_S390_CPU_TOPOLOGY 222
#ifdef KVM_CAP_IRQ_ROUTING