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

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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 vsmt_mode being returned when the KVM_CAP_PPC_SMT capability is
subsequently queried for the VM. This capability is only supported by subsequently queried for the VM. This capability is only supported by
HV KVM, and can only be set before any VCPUs have been created. 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 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 Future versions of kvm may implement additional events. These will get
indicated by returning a higher number from KVM_CHECK_EXTENSION and will be indicated by returning a higher number from KVM_CHECK_EXTENSION and will be
listed above. 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
View File

@ -566,6 +566,16 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
r = threads_per_subcore; r = threads_per_subcore;
} }
break; 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: case KVM_CAP_PPC_RMA:
r = 0; r = 0;
break; 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_X86_GUEST_MWAIT 143
#define KVM_CAP_ARM_USER_IRQ 144 #define KVM_CAP_ARM_USER_IRQ 144
#define KVM_CAP_PPC_FWNMI 145 #define KVM_CAP_PPC_FWNMI 145
#define KVM_CAP_PPC_SMT_POSSIBLE 146
#ifdef KVM_CAP_IRQ_ROUTING #ifdef KVM_CAP_IRQ_ROUTING