arm64 requires a vcpu fd (KVM_HAS_DEVICE_ATTR vcpu ioctl) to probe
support for steal-time. However this is unnecessary, as only a KVM
fd is required, and it complicates userspace (userspace may prefer
delaying vcpu creation until after feature probing). Introduce a cap
that can be checked instead. While x86 can already probe steal-time
support with a kvm fd (KVM_GET_SUPPORTED_CPUID), we add the cap there
too for consistency.
Signed-off-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Steven Price <steven.price@arm.com>
Link: https://lore.kernel.org/r/20200804170604.42662-7-drjones@redhat.com
This capability governs the KVM_S390_PV_COMMAND ioctl and the
KVM_MP_STATE_LOAD MP_STATE. KVM_SET_MP_STATE can fail for protected
guests when the state change is invalid.
+
+8.24 KVM_CAP_STEAL_TIME
+-----------------------
+
+:Architectures: arm64, x86
+
+This capability indicates that KVM supports steal time accounting.
+When steal time accounting is supported it may be enabled with
+architecture-specific interfaces. This capability and the architecture-
+specific interfaces must be consistent, i.e. if one says the feature
+is supported, than the other should as well and vice versa. For arm64
+see Documentation/virt/kvm/devices/vcpu.rst "KVM_ARM_VCPU_PVTIME_CTRL".
+For x86 see Documentation/virt/kvm/msr.rst "MSR_KVM_STEAL_TIME".
gpa_t kvm_init_stolen_time(struct kvm_vcpu *vcpu);
void kvm_update_stolen_time(struct kvm_vcpu *vcpu);
+bool kvm_arm_pvtime_supported(void);
int kvm_arm_pvtime_set_attr(struct kvm_vcpu *vcpu,
struct kvm_device_attr *attr);
int kvm_arm_pvtime_get_attr(struct kvm_vcpu *vcpu,
*/
r = 1;
break;
+ case KVM_CAP_STEAL_TIME:
+ r = kvm_arm_pvtime_supported();
+ break;
default:
r = kvm_arch_vm_ioctl_check_extension(kvm, ext);
break;
return base;
}
-static bool kvm_arm_pvtime_supported(void)
+bool kvm_arm_pvtime_supported(void)
{
return !!sched_info_on();
}
case KVM_CAP_SMALLER_MAXPHYADDR:
r = (int) allow_smaller_maxphyaddr;
break;
+ case KVM_CAP_STEAL_TIME:
+ r = sched_info_on();
+ break;
default:
break;
}
#define KVM_CAP_LAST_CPU 184
#define KVM_CAP_SMALLER_MAXPHYADDR 185
#define KVM_CAP_S390_DIAG318 186
+#define KVM_CAP_STEAL_TIME 187
#ifdef KVM_CAP_IRQ_ROUTING