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KVM: PPC: Book3S HV: Add capability to report possible virtual SMT modes 

Now that userspace can set the virtual SMT mode by enabling the
KVM_CAP_PPC_SMT capability, it is useful for userspace to be able
to query the set of possible virtual SMT modes.  This provides a
new capability, KVM_CAP_PPC_SMT_POSSIBLE, to provide this
information.  The return value is a bitmap of possible modes, with
bit N set if virtual SMT mode 2^N is available.  That is, 1 indicates
SMT1 is available, 2 indicates that SMT2 is available, 3 indicates
that both SMT1 and SMT2 are available, and so on.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This commit is contained in:
Paul Mackerras 2017-06-21 16:01:27 +10:00
parent e20bbd3d8d
commit 2ed4f9dd19
3 changed files with 22 additions and 0 deletions
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11
Documentation/virtual/kvm/api.txt
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@ -4010,6 +4010,8 @@ be 0. A successful call to enable this capability will result in
vsmt_mode being returned when the KVM_CAP_PPC_SMT capability is
subsequently queried for the VM. This capability is only supported by
HV KVM, and can only be set before any VCPUs have been created.
The KVM_CAP_PPC_SMT_POSSIBLE capability indicates which virtual SMT
modes are available.
7.12 KVM_CAP_PPC_FWNMI
@ -4183,3 +4185,12 @@ Currently the following bits are defined for the device_irq_level bitmap:
Future versions of kvm may implement additional events. These will get
indicated by returning a higher number from KVM_CHECK_EXTENSION and will be
listed above.
8.10 KVM_CAP_PPC_SMT_POSSIBLE
Architectures: ppc
Querying this capability returns a bitmap indicating the possible
virtual SMT modes that can be set using KVM_CAP_PPC_SMT. If bit N
(counting from the right) is set, then a virtual SMT mode of 2^N is
available.

10
arch/powerpc/kvm/powerpc.c
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@ -566,6 +566,16 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
r = threads_per_subcore;
}
break;
case KVM_CAP_PPC_SMT_POSSIBLE:
r = 1;
if (hv_enabled) {
if (!cpu_has_feature(CPU_FTR_ARCH_300))
r = ((threads_per_subcore << 1) - 1);
else
/* P9 can emulate dbells, so allow any mode */
r = 8 | 4 | 2 | 1;
}
break;
case KVM_CAP_PPC_RMA:
r = 0;
break;

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

@ -896,6 +896,7 @@ struct kvm_ppc_resize_hpt {
#define KVM_CAP_X86_GUEST_MWAIT 143
#define KVM_CAP_ARM_USER_IRQ 144
#define KVM_CAP_PPC_FWNMI 145
#define KVM_CAP_PPC_SMT_POSSIBLE 146
#ifdef KVM_CAP_IRQ_ROUTING