Commit b2467e74 authored Nov 25, 2015 by Haozhong Zhang Committed by Paolo Bonzini Nov 25, 2015

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



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>

parent 8bd142c0

arch/x86/kvm/vmx.c

+0 −5

Original line number	Diff line number	Diff line
		@@ -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;