nEPT: Support LOAD_IA32_EFER entry/exit controls for L1
authorNadav Har'El <nyh@il.ibm.com>
Mon, 5 Aug 2013 08:07:06 +0000 (11:07 +0300)
committerPaolo Bonzini <pbonzini@redhat.com>
Wed, 7 Aug 2013 13:57:34 +0000 (15:57 +0200)
commit8049d651e8789b15baaf2a8b888d8919df1152a9
treefcc048550ed2bc48c2ee56c2a615e3f16a8956a3
parent027664216d37afe80101de91f73dfbaf6b36ee65
nEPT: Support LOAD_IA32_EFER entry/exit controls for L1

Recent KVM, since http://kerneltrap.org/mailarchive/linux-kvm/2010/5/2/6261577
switch the EFER MSR when EPT is used and the host and guest have different
NX bits. So if we add support for nested EPT (L1 guest using EPT to run L2)
and want to be able to run recent KVM as L1, we need to allow L1 to use this
EFER switching feature.

To do this EFER switching, KVM uses VM_ENTRY/EXIT_LOAD_IA32_EFER if available,
and if it isn't, it uses the generic VM_ENTRY/EXIT_MSR_LOAD. This patch adds
support for the former (the latter is still unsupported).

Nested entry and exit emulation (prepare_vmcs_02 and load_vmcs12_host_state,
respectively) already handled VM_ENTRY/EXIT_LOAD_IA32_EFER correctly. So all
that's left to do in this patch is to properly advertise this feature to L1.

Note that vmcs12's VM_ENTRY/EXIT_LOAD_IA32_EFER are emulated by L0, by using
vmx_set_efer (which itself sets one of several vmcs02 fields), so we always
support this feature, regardless of whether the host supports it.

Reviewed-by: Orit Wasserman <owasserm@redhat.com>
Signed-off-by: Nadav Har'El <nyh@il.ibm.com>
Signed-off-by: Jun Nakajima <jun.nakajima@intel.com>
Signed-off-by: Xinhao Xu <xinhao.xu@intel.com>
Signed-off-by: Yang Zhang <yang.z.zhang@Intel.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
arch/x86/kvm/vmx.c