From: Paul Mackerras <paulus@ozlabs.org>
Date: Wed, 21 Jun 2017 16:01:27 +1000
Subject: KVM: PPC: Book3S HV: Add capability to report possible virtual SMT
modes
Patch-mainline: v4.13-rc1
Git-commit: 2ed4f9dd19c0f76f7fb56c4b201696d29149325c
References: bsc#1077761
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>
Acked-by: Alexander Graf <agraf@suse.de>
---
Documentation/virtual/kvm/api.txt | 11 +++++++++++
arch/powerpc/kvm/powerpc.c | 10 ++++++++++
include/uapi/linux/kvm.h | 1 +
3 files changed, 22 insertions(+)
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -4145,6 +4145,8 @@ be 0. A successful call to enable this
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
@@ -4318,3 +4320,12 @@ Currently the following bits are defined
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.
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -565,6 +565,16 @@ int kvm_vm_ioctl_check_extension(struct
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;
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -926,6 +926,7 @@ struct kvm_ppc_resize_hpt {
#define KVM_CAP_ARM_USER_IRQ 144
#define KVM_CAP_S390_CMMA_MIGRATION 145
#define KVM_CAP_PPC_FWNMI 146
+#define KVM_CAP_PPC_SMT_POSSIBLE 147
#ifdef KVM_CAP_IRQ_ROUTING