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| author |   Tianyu Lan <Tianyu.Lan@microsoft.com> | 2019-08-22 22:30:20 +0800 |
|---|---|---|
| committer |   Paolo Bonzini <pbonzini@redhat.com> | 2019-09-24 13:37:13 +0200 |
| commit | 344c6c804703841d2bff4d68d7390ba726053874 (patch) | |
| tree | c5914bdd31fcc5a5c9fdcde1b4de5ce8024ef907 /Documentation | |
| parent | x86/Hyper-V: Fix definition of struct hv_vp_assist_page (diff) | |
| download | linux-dev-344c6c804703841d2bff4d68d7390ba726053874.tar.xz linux-dev-344c6c804703841d2bff4d68d7390ba726053874.zip | |
KVM/Hyper-V: Add new KVM capability KVM_CAP_HYPERV_DIRECT_TLBFLUSH
Hyper-V direct tlb flush function should be enabled for
guest that only uses Hyper-V hypercall. User space
hypervisor(e.g, Qemu) can disable KVM identification in
CPUID and just exposes Hyper-V identification to make
sure the precondition. Add new KVM capability KVM_CAP_
HYPERV_DIRECT_TLBFLUSH for user space to enable Hyper-V
direct tlb function and this function is default to be
disabled in KVM.
Signed-off-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/virt/kvm/api.txt | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/Documentation/virt/kvm/api.txt b/Documentation/virt/kvm/api.txt index 136f1eef3712..4833904d32a5 100644 --- a/Documentation/virt/kvm/api.txt +++ b/Documentation/virt/kvm/api.txt @@ -5309,3 +5309,16 @@ Architectures: x86 This capability indicates that KVM supports paravirtualized Hyper-V IPI send hypercalls: HvCallSendSyntheticClusterIpi, HvCallSendSyntheticClusterIpiEx. +8.21 KVM_CAP_HYPERV_DIRECT_TLBFLUSH + +Architecture: x86 + +This capability indicates that KVM running on top of Hyper-V hypervisor +enables Direct TLB flush for its guests meaning that TLB flush +hypercalls are handled by Level 0 hypervisor (Hyper-V) bypassing KVM. +Due to the different ABI for hypercall parameters between Hyper-V and +KVM, enabling this capability effectively disables all hypercall +handling by KVM (as some KVM hypercall may be mistakenly treated as TLB +flush hypercalls by Hyper-V) so userspace should disable KVM identification +in CPUID and only exposes Hyper-V identification. In this case, guest +thinks it's running on Hyper-V and only use Hyper-V hypercalls. |