KVM: nVMX: Always reflect #NM VM-exits to L1

When bit 3 (corresponding to CR0.TS) of the VMCS12 cr0_guest_host_mask
field is clear, the VMCS12 guest_cr0 field does not necessarily hold
the current value of the L2 CR0.TS bit, so the code that checked for
L2's CR0.TS bit being set was incorrect. Moreover, I'm not sure that
the CR0.TS check was adequate. (What if L2's CR0.EM was set, for
instance?)

Fortunately, lazy FPU has gone away, so L0 has lost all interest in
intercepting #NM exceptions. See commit bd7e5b0899a4 ("KVM: x86:
remove code for lazy FPU handling"). Therefore, there is no longer any
question of which hypervisor gets first dibs. The #NM VM-exit should
always be reflected to L1. (Note that the corresponding bit must be
set in the VMCS12 exception_bitmap field for there to be an #NM
VM-exit at all.)

Fixes: ccf9844e5d99c ("kvm, vmx: Really fix lazy FPU on nested guest")
Reported-by: Abhiroop Dabral <adabral@paloaltonetworks.com>
Signed-off-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Peter Shier <pshier@google.com>
Tested-by: Abhiroop Dabral <adabral@paloaltonetworks.com>
Reviewed-by: Liran Alon <liran.alon@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index eee1b60023fd412f84afe99e3b5fa8cc822d0e61..b967f89963bf12a2f88e7c43440e95cdfcd07564 100644 (file)
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -1613,11 +1613,6 @@ static inline bool is_page_fault(u32 intr_info)
        return is_exception_n(intr_info, PF_VECTOR);
 }
 
-static inline bool is_no_device(u32 intr_info)
-{
-       return is_exception_n(intr_info, NM_VECTOR);
-}
-
 static inline bool is_invalid_opcode(u32 intr_info)
 {
        return is_exception_n(intr_info, UD_VECTOR);
@@ -9653,9 +9648,6 @@ static bool nested_vmx_exit_reflected(struct kvm_vcpu *vcpu, u32 exit_reason)
                        return false;
                else if (is_page_fault(intr_info))
                        return !vmx->vcpu.arch.apf.host_apf_reason && enable_ept;
-               else if (is_no_device(intr_info) &&
-                        !(vmcs12->guest_cr0 & X86_CR0_TS))
-                       return false;
                else if (is_debug(intr_info) &&
                         vcpu->guest_debug &
                         (KVM_GUESTDBG_SINGLESTEP | KVM_GUESTDBG_USE_HW_BP))