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KVM: nVMX: remove incorrect vpid check in nested invvpid emulation

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This patch removes the vpid check when emulating nested invvpid
instruction of type all-contexts invalidation. The existing code is
incorrect because:
 (1) According to Intel SDM Vol 3, Section "INVVPID - Invalidate
     Translations Based on VPID", invvpid instruction does not check
     vpid in the invvpid descriptor when its type is all-contexts
     invalidation.
 (2) According to the same document, invvpid of type all-contexts
     invalidation does not require there is an active VMCS, so/and
     get_vmcs12() in the existing code may result in a NULL-pointer
     dereference. In practice, it can crash both KVM itself and L1
     hypervisors that use invvpid (e.g. Xen).

Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Haozhong Zhang 2015-11-25 17:21:39 +08:00 • committed by Paolo Bonzini
parent 8bd142c016
commit b2467e744f
1 changed files with 0 additions and 5 deletions
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5
arch/x86/kvm/vmx.c
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@ -7394,11 +7394,6 @@ static int handle_invvpid(struct kvm_vcpu *vcpu)
switch (type) {
case VMX_VPID_EXTENT_ALL_CONTEXT:
if (get_vmcs12(vcpu)->virtual_processor_id == 0) {
nested_vmx_failValid(vcpu,
VMXERR_INVALID_OPERAND_TO_INVEPT_INVVPID);
return 1;
}
__vmx_flush_tlb(vcpu, to_vmx(vcpu)->nested.vpid02);
nested_vmx_succeed(vcpu);
break;