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authorRoman Kagan <rkagan@virtuozzo.com>2017-07-14 17:13:20 +0300
committerRadim Krčmář <rkrcmar@redhat.com>2017-07-14 16:28:18 +0200
commitd3457c877b14aaee8c52923eedf05a3b78af0476 (patch)
tree619e33c612f455e8b15d22ce0eee536d657e50f3 /include/uapi
parent52a5c155cf79f1f059bffebf4d06d0249573e659 (diff)
kvm: x86: hyperv: make VP_INDEX managed by userspace
Hyper-V identifies vCPUs by Virtual Processor Index, which can be queried via HV_X64_MSR_VP_INDEX msr. It is defined by the spec as a sequential number which can't exceed the maximum number of vCPUs per VM. APIC ids can be sparse and thus aren't a valid replacement for VP indices. Current KVM uses its internal vcpu index as VP_INDEX. However, to make it predictable and persistent across VM migrations, the userspace has to control the value of VP_INDEX. This patch achieves that, by storing vp_index explicitly on vcpu, and allowing HV_X64_MSR_VP_INDEX to be set from the host side. For compatibility it's initialized to KVM vcpu index. Also a few variables are renamed to make clear distinction betweed this Hyper-V vp_index and KVM vcpu_id (== APIC id). Besides, a new capability, KVM_CAP_HYPERV_VP_INDEX, is added to allow the userspace to skip attempting msr writes where unsupported, to avoid spamming error logs. Signed-off-by: Roman Kagan <rkagan@virtuozzo.com> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Diffstat (limited to 'include/uapi')
-rw-r--r--include/uapi/linux/kvm.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 38b2cfbc8112..6cd63c18708a 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -928,6 +928,7 @@ struct kvm_ppc_resize_hpt {
#define KVM_CAP_PPC_FWNMI 146
#define KVM_CAP_PPC_SMT_POSSIBLE 147
#define KVM_CAP_HYPERV_SYNIC2 148
+#define KVM_CAP_HYPERV_VP_INDEX 149
#ifdef KVM_CAP_IRQ_ROUTING

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