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| author | Roman Kagan <rkagan@virtuozzo.com> | 2017-07-14 17:13:20 +0300 |
|---|---|---|
| committer | Radim Krčmář <rkrcmar@redhat.com> | 2017-07-14 17:28:18 +0300 |
| commit | d3457c877b14aaee8c52923eedf05a3b78af0476 (patch) | |
| tree | 619e33c612f455e8b15d22ce0eee536d657e50f3 /include/uapi | |
| parent | 52a5c155cf79f1f059bffebf4d06d0249573e659 (diff) | |
| download | linux-d3457c877b14aaee8c52923eedf05a3b78af0476.tar.xz | |
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.h | 1 |
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 |