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>

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 87acc5221740a588d256f9f0ed4059d366165872..af823a388c1994ba244e3ef0098f1a578408101e 100644 (file)
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -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;