kvm: vmx: Do not disable intercepts for BNDCFGS

The MSR permission bitmaps are shared by all VMs. However, some VMs
may not be configured to support MPX, even when the host does. If the
host supports VMX and the guest does not, we should intercept accesses
to the BNDCFGS MSR, so that we can synthesize a #GP
fault. Furthermore, if the host does not support MPX and the
"ignore_msrs" kvm kernel parameter is set, then we should intercept
accesses to the BNDCFGS MSR, so that we can skip over the rdmsr/wrmsr
without raising a #GP fault.

Fixes: 559bcb8e7c107e1a ("KVM: x86: Intel MPX vmx and msr handle")
Signed-off-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 60fa010d3fa13947858ab697a042845256e78d12..577bb1d75e1eadccca36eab7742a7678bd0363cf 100644 (file)
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -6547,7 +6547,6 @@ static __init int hardware_setup(void)
        vmx_disable_intercept_for_msr(MSR_IA32_SYSENTER_CS, false);
        vmx_disable_intercept_for_msr(MSR_IA32_SYSENTER_ESP, false);
        vmx_disable_intercept_for_msr(MSR_IA32_SYSENTER_EIP, false);
-       vmx_disable_intercept_for_msr(MSR_IA32_BNDCFGS, true);
 
        memcpy(vmx_msr_bitmap_legacy_x2apic_apicv,
                        vmx_msr_bitmap_legacy, PAGE_SIZE);